Chemistry 350 Organic Chemistry I

Chemistry 350 Organic Chemistry I

Student Manual

Athabasca University

Course Team Course Professor: Lawton Shaw Course Authors: Arthur Last and Dietmar Kennepohl Revisions: Dietmar Kennpohl (1996-2004); Ross Witherell (2010) Reviewer, 2004: David Law Editor: Gilda Sanders Visual Presentation: Athabasca University Digital Media Technology Unit Cover Design: Jingfen Zhang

Cover Image: Alchymist, in Search of the Philosopher’s Stone, Discovers Phosphorus, and prays for the successful Conclusion of his operation, as was the custom of the Ancient Chymical Astrologers, by Joseph Wright of Derby (1734-1797). This painting, created in 1771, is now held by the Derby Museum and Art Gallery, Derby UK. Public Domain. Note: This course is a revision of a part of Chemistry 345: Organic Chemistry by Arthur Last, copyright © 1991 by Athabasca University.

Every effort has been taken to ensure that these materials comply with the requirements of copyright clearances and appropriate credits. Athabasca University will attempt to incorporate in future printings any corrections which are communicated to it. The inclusion of any material in this publication is strictly in accord with the consents obtained and Athabasca University does not authorize or license any further reproduction or use without the consent of the copyright holder. © Athabasca University 2010

All rights reserved Printed in Canada CMID 552838 Revision 6

Contents Course Information The Course . . . . . . . . . . . . . . . . . . . . . . . . . The MyAU Portal . . . . . . . . . . . . . . . . . . . . . Your Student ID Number . . . . . . . . . . . . . . . . Freedom of Information and Protection of Privacy . The Athabasca University Calendar . . . . . . . . . . Course Materials . . . . . . . . . . . . . . . . . . . . . Other Items . . . . . . . . . . . . . . . . . . . . . . . . . Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . Course Design . . . . . . . . . . . . . . . . . . . . . . . Laboratories . . . . . . . . . . . . . . . . . . . . . . . . Your Tutor . . . . . . . . . . . . . . . . . . . . . . . . . The Course Professor . . . . . . . . . . . . . . . . . . . Services to Students . . . . . . . . . . . . . . . . . . . . Library Services . . . . . . . . . . . . . . . . . . . . . . Study Strategies . . . . . . . . . . . . . . . . . . . . . . How to Use the Study Guide . . . . . . . . . . . . . . Course Outline and Study Schedules . . . . . . . . . Assessment . . . . . . . . . . . . . . . . . . . . . . . . . Applying for and Writing Examinations . . . . . . . Student Conduct and Appeals . . . . . . . . . . . . . Intellectual Indebtedness . . . . . . . . . . . . . . . . Transcripts . . . . . . . . . . . . . . . . . . . . . . . . . Transferring Credit . . . . . . . . . . . . . . . . . . . . Applying for Extensions . . . . . . . . . . . . . . . . . Sample Examinations Sample Midterm Examination . . . . . . . . . Sample Midterm Examination—Answer Key Sample Final Examination . . . . . . . . . . . . Sample Final Examination—Answer Key . .

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Course Information

Organic Chemistry I

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Chemistry 350 / Student Manual

The Course Welcome to Chemistry 350: Organic Chemistry I, a three-credit, senior-level, laboratory science course. We assume that all students registering in this course will have completed a university-level course in general chemistry equivalent to Athabasca University’s Chemistry 217/218 (formerly Chemistry 209). If this is not the case, you should contact the course professor immediately. Organic Chemistry I deals with the chemistry of carbon compounds through a study of the characteristic reactions of the common functional groups. Particular emphasis is placed on the study of reaction mechanisms, in an attempt to show similarities between apparently unrelated reactions. The importance of stereochemistry is stressed throughout the course. The compulsory laboratory component of Chemistry 350 introduces the basic techniques employed in modern organic chemistry laboratories. Experiments have been selected to illustrate many of the principles encountered in the theoretical part of the course. The course outline on page 17 of this manual gives a more detailed description of the course contents. This Student Manual provides you with some essential information about the design of the course, the course materials, and the procedures you should follow to obtain the maximum benefit from your studies. Please read it carefully and keep it in a safe place. Note: These course materials have been designed for students who are taking the individualized-study version of this course. Students who are in a grouped-study environment should follow the course outline, study schedule and learning activities provided by their instructor.

The MyAU Portal MyAU is a personalized portal to the University where you can quickly access information that is relevant to you. Through myAU, you can view personal information, such as library accounts and assignment marks and course grades, and take care of administrative matters, such as booking examinations, submitting assignments, applying for extensions, registering for courses, and so on. Athabasca University will also communicate directly with you through myAU. Check the Message Centre on your myAU home page for general information and for mail addressed specifically to you. To login at http://my.athabascau.ca/ enter your student ID number and password where requested. If you are having browser difficulties or you need help, refer to myAU Help at http://www.athabascau.ca/uportal/help/index.php Organic Chemistry I

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Your Student ID Number In contacts with your tutor, on assignments, or in any correspondence or other contact with the University, you are asked to provide your student ID number. Record this number in the space below. Having your student ID number will help University personnel to process requests, grades and administrative matters more quickly. Student ID number: Note: It is important that we receive notification of any change of address or telephone number. Please inform the Office of the Registrar whenever such a change occurs. You can do so through your myAU portal, or you can use a student change of information form (see the section of this manual titled “Forms”). In addition, you should send change-of-address cards to your tutor and to the course professor, so that your student files can be kept up-to-date.

Freedom of Information and Protection of Privacy The personal information and records collected and maintained by the University as a result of a student’s registration in this course, such as completed assignments and examinations, electronic communications and correspondence, are subject to University policies and the privacy and access provisions of the Alberta Freedom of Information and Protection of Privacy Act.

The Athabasca University Calendar Because Athabasca University’s policies, practices, and procedures change over time, some of the information in this Student Manual may lose its currency between course revisions. Students are therefore advised to refer to the current Athabasca University Calendar on important issues concerning University policies, procedures and practices. In the event of any discrepancy between the printed version of the Calendar and the official web-based Calendar, the web-based version will be binding.

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Course Materials The package you received should include each of the items listed below. If anything is missing from your package, please contact the Course Materials division of Athabasca University as soon as possible. If you live in Canada or the United States, you can use email to contact Course Materials: [email protected] You can also call 1-800-788-9041, choose option 3 from the menu, and enter extension 6366 when prompted. Students who live outside of Canada or the United States can contact Course Materials by email. You can also write in care of Course Materials, Tim Byrne Centre, 400 Hwy 2 South, Athabasca, AB T9S 1A4.

Textbooks McMurry, John. Organic Chemistry, 7th ed. Pacific Grove, CA: Brooks/Cole Publishing Co., 2008. McMurry, Susan. Study Guide and Student Solutions Manual for McMurry’s Organic Chemistry, 7th ed. Pacific Grove, CA: Brooks/Cole Publishing Co., 2008.

Athabasca University Materials Chemistry 350: Organic Chemistry I. Student Manual. Athabasca, AB: Athabasca University, 2010. You are now reading the Student Manual. Chemistry 350: Organic Chemistry I. Study Guide. Athabasca, AB: Athabasca University, 2010. The Study Guide, as its name implies, is designed to guide your study of the course textbook. Chemistry 350: Organic Chemistry I. Assignment Manual. Athabasca, AB: Athabasca University, 2010. The Assignment Manual contains the self tests and answers to the self tests, as well as the two “tutor-marked assignments.” Chemistry 350: Organic Chemistry I. Laboratory Manual. Athabasca, AB: Athabasca University, 2010.

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Other Items The items listed below are not supplied; you should purchase them before you begin to work on the course. You will need ● an electronic calculator capable of handling logarithms and exponentials.

Remember: Take your calculator with you whenever you write an examination or attend a laboratory session. ● a lab coat. You will not be allowed to attend lab sessions without one. ● a laboratory notebook. ● other stationery, including paper for assignments, pens, pencils, a

ruler, etc.

Forms The forms you need to submit assignments, request examinations or inform the University of a change in your status as a student are available through your myAU home page, or for download from the Office of the Registrar’s Online Services (OROS) website: http://www.athabascau.ca/registrar/forms.php If you do not have access to the Internet or are unable to obtain the forms online, please contact the Athabasca University Information Centre, toll free, at 1.800.788.9041 to request that printed copies be sent to you. For Chemistry 350, you will need at least two tutor-marked exercise forms and two examination request forms.

Course Design The course materials are designed for self-instruction and individualizedstudy. What you should learn and how you should learn it are described in the Study Guide. This book contains 16 units, each of which corresponds to one of the chapters in Organic Chemistry, 7th ed., by John McMurry. Each unit in the Study Guide contains a preview, a list of learning objectives, a series of subsections corresponding to chapter subsections, and some hints on how to work through the unit. Let us look at exactly what you can expect to find under each of these headings.

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Unit Preview The “Unit Preview” is a brief discussion that outlines the overall approach taken by the author in the relevant chapter of Organic Chemistry.

Unit Objectives In this section, we inform you of the overall objectives that we expect you to be able to fulfill when you have finished studying the unit.

Sections The sections form the bulk of each unit. Each section in the Study Guide normally contains the following features: 1. a list of objectives which are more detailed than those provided under the heading “Unit Objectives,” and which may be one of the most valuable features of the Study Guide, because they tell you explicitly what you need to understand and to be able to do for each unit of the course. Questions on the examinations and tutor-marked assignments are based only on the unit objectives. However, you should be aware that many questions will require you to demonstrate mastery of a number of related objectives, and that you should not place too narrow an interpretation on each objective. 2. a list of key terms introduced in the section. Unless we have indicated otherwise, definitions of these key terms are provided in “Appendix C—Glossary,” beginning on page A10 of Organic Chemistry, 7th ed. 3. study notes, which may include hints on how to study the material effectively, additional information, and details of any errors that occur in the textbook. 4. a list of suggested exercises. These exercises are designed to improve your understanding of the material you have just studied and to develop your problem-solving skills. Refer to your notes and to the textbook when you attempt the exercises. The answers to all the exercises are provided in the Solutions Manual or in “Appendix D—Answers to In-text Problems,” beginning on page A30 of the textbook. Do not spend a large amount of time on any one exercise. If you are unable to make any progress after a few minutes of concentrated work, use the answers to help. For further information, see the section of this manual titled “How to Use Your Study Guide.” There are two (2) tutor-marked assignments (TMAs) in this course. These assignments contribute to the overall mark that you will obtain for the course (see the “Assessment” section of this manual). Units 1 and 2 have entry-level tests designed to determine your mastery of the fundamentals. If you obtain a high score on the test in one of these units, you may proceed immediately to the next unit. Organic Chemistry I

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Self tests are given at the end of Units 5, 7, 9, 11, 14 and 16. These tests are designed to allow you to measure your progress in the course—they are not a comprehensive overview of the material, nor are they at the same level of difficulty that you will encounter in the midterm and final examinations. [Sample examinations are given in this manual.] If you have difficulty with any self test, you should go back and review the material before going on. The textbook by McMurry contains most of the information you will need to pass this course. It is a standard textbook used in many universities and colleges throughout North America. It was chosen because it offers clear explanations and interesting discussions of the material we wished this course to cover. In addition, we felt that this textbook has an advantage in that it includes some discussion of a number of advances made in organic chemistry during the last decade. The chapters are relatively short, and the textbook contains problems, exercises and some review chapters. Each chapter of the textbook concludes with a useful summary, and where appropriate, a list of the reactions introduced in the chapter. These reviews are excellent for quick reference and will help you to prepare for examinations. You should use a set of molecular models to assist you in understanding the stereochemical aspects of the course. If you cannot obtain a set of molecular models elsewhere, you may order one from the Athabasca University Library (see the section of this manual titled “Library Services”). You may use molecular models during examinations.

Laboratories You must complete about 32 hours of laboratory work to obtain credit in this course. Labs are typically held for week-long sessions during the summer in Athabasca, or for full-day sessions on weekends in Edmonton in the rest of the year. The Lab Coordinator will be able to provide up-to-date information, or you may go to our Lab Information website at: http://science.pc.athabascau.ca/labinfo.nsf You must contact the Lab Coordinator to book into a scheduled laboratory session. Students in Canada and the United States can reach the Lab Coordinator by calling 1-800-788-9041 (the extension is 6276). All students can use electronic mail to contact the Lab Coordinator at [email protected] Information about the laboratory program and the experiments to be carried out is included in the Laboratory Manual. Note that your lab work accounts for 20 per cent of your overall course mark. You must satisfactorily complete and write up a specified minimum number of experiments to obtain credit for this course.

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Your Tutor Athabasca University provides each student in each course with a tutor whose responsibility is to help the student complete the course successfully. A letter containing your tutor’s name, address, telephone number and tutoring hours was mailed to you shortly before your official start date. If you have not yet received your tutor letter, please contact Learning Services—Tutorial at Athabasca University as soon as possible. Students in Canada or the United States can call 1-800-788-9041 (extension 6196); all students can send electronic mail to [email protected] Note: If you have chosen to receive communications from Athabasca University in electronic form, be sure to check your myAU portal for your tutor letter. Your tutor has excellent academic qualifications, and is committed to helping students learning at a distance. He or she is available to answer your questions about course content or how to approach a problem or an assignment, and can direct you to the right person or department to help you with other problems that may be hindering your progress in your course or program. In addition, your tutor will be responsible for marking your assignments. In general, you should call your tutor first with any queries about Athabasca University. The tutor letter will help you become acquainted with your tutor and will provide information about your tutor’s schedule. If you have not yet received a call from your tutor, do not hesitate to make the first call yourself. If you live in Canada or the United States, you can call your tutor, toll free, during his or her tutoring hours, using the information provided in the tutor letter. If you live outside of Canada or the United States, please refer to the tutor letter and the current Athabasca University Calendar for information about calling your tutor. We suggest that you contact your tutor as soon as you receive the course materials, and then get into the habit of communicating regularly, when you complete a unit or when you run into any special problem. We have found that students who maintain regular contact with their tutors are most likely to be successful in completing their courses, so do keep in touch. You may find it useful to schedule a regular study period when your tutor is available so that you can contact him or her when questions arise. If you are unable to take advantage of the regular tutoring hours, contact your tutor or the course professor to determine whether alternative arrangements can be made. If you use postal mail to send an assignment to your tutor, be sure to attach a tutor-marked exercise form, and to keep a copy, at least a rough draft, in case the original goes astray in the mail. If you take this course through the Moodle course management system, you may be instructed to use the “Assignment Drop Box” to submit your assignments. If you wish to submit your assignments electronically outside of the Moodle system, contact your Organic Chemistry I

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tutor to discuss appropriate formats. An electronic version of the tutor-marked exercise form is available online through your “myAU” portal. In any case, allow several working days, in addition to mailing time each way if applicable, before you expect to receive the graded assignment. Your tutor will be pleased to provide additional feedback. Be sure to mention any questions you have about the assignment or the grade. Keep your tutor’s letter of introduction with your course materials, and use the space below to record information about your tutor. Tutor’s name: Address:

Telephone number: Electronic mail address: Tutoring hours: Note: If we are to keep you informed of upcoming laboratory sessions, etc., it is important that we receive notification of any change of address or telephone number. Please inform the Office of the Registrar whenever such a change occurs.

The Course Professor The course professor is the member of Athabasca University’s academic staff who is in charge of a given course. The professor works directly with tutors on both academic and administrative matters. If you have difficulties you cannot resolve with your tutor, you may wish to speak with the professor directly. You should also address any questions about credit records or centrally marked examinations to the professor. The professor can also provide general information about program planning and curriculum development. The course professor welcomes students’ comments on the course.

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Services to Students Athabasca University offers a wide range of services to its students. The Athabasca University Information Centre (1.800.788.9041) can help you find the answer to most administrative questions. The Centre is staffed on regular business days from 7:00 a.m. to 5:30 p.m., Mountain Time. Advisors are available to assist students in planning their programs and selecting appropriate courses. Counselors assist students in improving their study skills and clarifying their educational goals. You may reach an advisor or counselor in several ways: by dialling 1.800.788.9041 and asking to speak with an advisor or counselor; by visiting Athabasca University’s Central Office in Athabasca, or the Athabasca University sites in Edmonton or Calgary; or by directing your query to http://www.askau.ca Students who are looking for information about student awards and advice about obtaining financial assistance are asked to contact the Office of the Registrar. You may do so by dialling 1.800.788.9041 and asking for the Office of the Registrar, or by inquiring through http://www.askau.ca Note: Students may write examinations at the Athabasca University sites in Athabasca, Edmonton or Calgary, or at the other locations listed online at http://www.athabascau.ca/registrar/invignet.php At the Athabasca University sites in Athabasca, Edmonton or Calgary, students can also order materials from the Library, and take care of various administrative matters, such as course registration and arrangements for extensions.

Indigenous Services at Athabasca University If you are a student of Indigenous ancestry (Aboriginal, First Nations, Indian, Inuit, Native, Métis), or a non-Indigenous student who is interested in identifying culturally appropriate services designed for Aboriginal students or counseling that is sensitive to the challenges Aboriginal students face, please contact the Centre for World Indigenous Knowledge and Research, by telephone at 1.800.788.9041, extension 2064, or by electronic mail at [email protected]

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Library Services The Athabasca University Library collection contains more than 140,000 books, many periodical titles and a range of audio-visual resources. The Library subscribes to over 100 online databases, providing full text access to selected articles from more than 20,000 journals. Athabasca University Library’s collection primarily supports Athabasca University courses and programs. Materials found in the print and electronic collections are available for use by our students, faculty and staff for reference and research purposes. Requests for library materials or services can be made, by email, phone, fax or mail, 24 hours a day (contact information is provided below). Responses to most requests are handled within 24 hours, or by the next business day. Borrowed materials are normally mailed to the student’s home address, along with a returnmail card.

Core Services to Students Athabasca University students registered in a course may ● borrow library materials. ● search the Library’s online catalogue (AUCAT). ● access resources through the Library’s website. ● receive library instruction and research assistance. ● request interlibrary loan (ILL) services for journal articles and

book chapters.

Digital Resources Access to online journal databases, the Digital Reference Centre (DRC), and the Digital Reading Room (DRR) is available from Athabasca University Library’s main web page http://library.athabascau.ca Tips on searching the journal databases and help with researching, writing and citing (referencing) can be found in the Help Centre http://library.athabascau.ca/help.php

Supplementary Materials University courses often require that students investigate material beyond the contents of the course materials package. Some Athabasca University course Study Guides list “Supplementary Materials,” including books, 12


journal articles or audio-visual materials, which students may find useful when completing assignments and course projects. The supplementary materials referenced in your course materials package are usually available from the Athabasca University Library or your local library. Contact the Athabasca University Library to request materials.

How the Library Gateway Works The Library website contains the Library’s online catalogue (AUCAT), and it is also the gateway to other online information. The website provides links to journal databases and other subscribed online resources, as well as to selected, publicly accessible Internet sites. Subscribed resources are available to Athabasca University students, faculty and staff. You will be required to enter your first and last names as your username and your student ID number as your password. The Library website also provides access to selected library catalogues from Canadian public and academic libraries.

Interlibrary Loans An interlibrary loan (ILL) involves one library borrowing materials from another on behalf of a library user. Athabasca University Library will request photocopies of journal articles and book chapters through Interlibrary Loans, if you provide the Library staff with a complete bibliographic citation (author, title of article, name of journal, volume and issue number, year of publication, and page numbers) for the requested item. You are not required to return these items to us. Allow sufficient time for the material to be ordered and received. More information on the Interlibrary Loan process is available on the Library website at http://aupac.lib.athabascau.ca/screens/ill.html

Contacts Athabasca University Library 1 University Drive Athabasca, AB Canada T9S 3A3 Library website: http://library.athabascau.ca E-mail: [email protected] Phone: 1.800.788.9041 (ext. 6254) Canada/US Fax: 780.675.6477

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Study Strategies Chemistry 350 is a three-credit course and must be completed within the six months of your official start date. This may seem like a long time, but procrastination can rapidly put you in a difficult position. We suggest you start right away and that you establish a study schedule. Your tutor can help you. How fast you proceed through the first few units will depend on your background in general chemistry. Most of the material covered in Units 1 and 2 is a review of the topics covered in a typical university-level general chemistry course, and you should be able to complete these units in less than a week. If your background is weak, you may have to put in extra time, and this may affect your chances of completing the course within the normal six-month contract period. If you find that you really have trouble with Units 1 and 2, you should discuss the situation with your tutor and consider withdrawing from the course or taking some action to improve your understanding of basic chemistry. At a traditional university, this course would normally be spread over one semester and take about 12-13 weeks to complete. If you wish to attain this rate, follow the 13-week study schedule shown in the “Course Outline and Study Schedules” section of this Student Manual. If you wish to proceed at somewhat slower rate, refer to the 18- and 24-week schedules when you plan your own personal study schedule. Should unforeseen circumstances put you in a position where you find that you cannot complete the course within the six-month contract period, check the Athabasca University Calendar for current regulations about extensions. Be certain to check well before the end of your course contract, to ensure that you meet any necessary deadlines. Although the amount of time that a student will need to spend on the course will depend on a variety of factors, students intending to complete the course in 13 weeks should be prepared to spend at least nine (9) hours per week on the course. You may need additional time when you have laboratory reports to write, or when you are reviewing for an examination. We suggest that you start in on Unit 1 now. As you work through it, make a note of any questions you have on content, study procedures, etc. Then, before you go on to the next unit, contact your tutor to clear up these questions. Remember that regular study habits can be a major contributing factor to ultimate success in this course.

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How to Use the Study Guide As you study each unit in Chemistry 350, follow the procedure outlined below. 1. Read the preview and the list of unit objectives at the beginning of the unit. At this stage, some students find it beneficial to obtain an overall picture of the unit by quickly reading through the whole chapter in the textbook. 2. Study each lesson in the unit by a. reading the objectives and study notes (if any). These notes may contain study hints or additional information, and will also identify any errors that occur in the relevant section of the textbook. b. reading the required pages in the textbook, and using the objectives and key terms to guide you in making your own notes. c. completing the assigned exercises, and checking your answers in the Study Guide, the Solutions Manual and the textbook. Note that your problem-solving ability will largely determine the overall grade that you receive in this course. 3. Review the unit by a. making sure that you understand each of the unit objectives and can do what they require. b. making sure that you can define and use the key terms. c. reading the summary and the summary of reactions (where appropriate) given at the end of the chapter in the textbook. d. completing a selection of the recommended exercises listed in the Study Guide. 4. Do the tutor-marked assignment (if there is one) and send it to your tutor, or do the self test (if there is one) and check your own progress. Warning: One of the problems with distance education is that, occasionally, lab reports, assignments, etc., get lost in the mail. As we can only give credit for work that is actually received, we strongly advise that you keep a rough copy of all of the work that you submit to your tutor for marking. Also, please make certain that you attach a “Tutor-marked Exercise” form, from the course package, to any work you submit for grading.

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Course Outline and Study Schedules The table below gives a brief course outline and suggests the amount of time students should spend on each unit for 13-, 18- and 24-week schedules. Note: Students who are receiving financial assistance may face special time constraints. Please check your course registration for any restrictions on the length of registration, and be prepared to adjust your schedule.

Unit number and title

13-week schedule

18-week schedule

24-week schedule

1

Structure and Bonding

Week 1

Week 1

Week 1

2

Polar Covalent Bonds: Acids and Bases

Week 1

Week 1

Week 1

3

Organic Compounds: Alkanes and Their Stereochemistry

Week 1

Week 1

Week 2

4

Organic Compounds: Cycloalkanes and Their Stereochemistry

Week 2

Week 2

Week 2

5

An Overview of Organic Reactions

Week 2

Week 3

Week 4

6

Alkenes: Structure and Reactivity

Week 3

Week 4

Week 5

7

Alkenes: Reactions and Synthesis

Week 3

Week 5

Week 6

8

Alkynes: An Introduction to Organic Synthesis

Week 4

Week 6

Week 7

9

Stereochemistry

Week 5

Week 7

Weeks 8/9

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Review for Midterm Examination

Week 6

Week 8

Week 10

10

Organohalides

Week 7

Week 9

Week 11

11

Reactions of Alkyl Halides: Nucleophilic Substitutions and Eliminations

Week 7

Week 10

Week 12

12

Structure Determination: MS and IRS

Week 8

Week 11

Weeks 13/14

13

Structure Determination: NMRS

Week 9

Weeks 12/13

Weeks 15/16

14

Conjugated Compounds and UV Spectroscopy

Week 10

Week 14

Weeks 17/18

15

Benzene and Aromaticity

Week 11

Week 15

Weeks 19/20

16

Chemistry of Benzene Electrophilic Aromatic Substitution

Week 12

Week 16

Weeks 21/22

A Brief Review of Organic Reactions

Week 13

Week 17

Week 23

Review for Final Examination

Week 13

Week 18

Week 24

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The table below allows you (with the help of your tutor) to plan a personalized study schedule. Begin by filling in the first few units, and keep track of how long each unit is taking you. Once you have done the first few units, you (and your tutor) should be able to come up with a realistic schedule for the rest of the course. You may wish to remove the page and display it in a prominent place, to help you keep track of your progress.

Unit or event

Planned completion date

Actual completion date

Time required (hours)

Action needed

Unit 1

Contact tutor re lab schedule; complete entry-level test

Unit 2

Complete entry-level test

Unit 3

See below, “Note 1.”

Unit 4 Unit 5

Complete first self test

Unit 6 Unit 7

Complete second self test

Unit 8

Complete TMA 1

Unit 9

Complete third self test

Midterm Unit 10

See below, “Note 2.”

Unit 11

Complete fourth self test

Unit 12 Unit 13 Unit 14

Complete fifth self test

Unit 15 Unit 16

Complete TMA 2

Review

Complete sixth self test

Final

Note 1: Check “Applying for and Writing Examinations,” in this manual, and note, on the schedule above, the date by which you must apply for the midterm exam. Note 2: Check “Applying for and Writing Examinations,” in this manual, and note, on the schedule above, the date by which you must apply for the final exam. Organic Chemistry I

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Assessment The assessment of students in this course is based on examinations, tutor-marked assignments and laboratory work. Details are given in the table below. To obtain credit for Chemistry 350, you must ● obtain an overall (composite) mark of at least 50%. ● achieve at least 45% on each of the two examinations. ● obtain an average of at least 60% on the tutor-marked assignments. ● achieve an average of at least 55% on the laboratory work.

Percentage of total mark

Component

Material covered

Midterm examination (2 hours)

Units 3-9

20%

Final examination (3 hours)

Entire Course

50%

Tutor-marked assignments

following Unit 8 and Unit 16

10%

Laboratory work

20%

All examinations are supervised and “closed-book.” However, you will be supplied with a periodic table and a list of appropriate data (constants, spectral data, etc.). Remember: You must be sure to have your own electronic calculator and molecular models with you when you write an examination. Note that while the emphasis of the final examination is on Units 10-16, you are still responsible for the material covered in Units 3-9. If you are not satisfied with the mark you obtain on your first attempt at an examination, you may rewrite that examination. There is a fee for this service. The supplemental examination will be similar in format to the first one, and the higher of the two marks will be used when your overall course mark is determined. You must write a supplemental if you obtain less than 45% on an examination. The following hints may help you to write examinations successfully. Write only when you and your tutor feel that you are adequately prepared, and when you have successfully completed the relevant tutor-marked assignments. Remember that the examination is based on the objectives outlined in the Study Guide. Many of the questions will be similar in format to those given in the tutor-marked assignments. For short-answer questions, do the ones that you find easiest first. This strategy has two benefits. First, you can more quickly accumulate enough Organic Chemistry I

19

marks to pass the examination. Second, you gain confidence to tackle the harder questions. For numerical problems, show your work! Part marks will be given for correct methods even if your answer is incorrect. The answers to numerical problems should be given to the correct number of significant figures and where appropriate, with the correct units. Marks may be deducted if answers are given to an incorrect number of significant figures or in the wrong (or no) units. Procedures for applying to write examinations may be found in the section of this Student Manual titled “Applying for an Examination,” below.

Applying for and Writing Examinations If you are requesting to write an examination at Athabasca University (Athabasca), Athabasca University (Edmonton), or Athabasca University (Calgary), you must request your examination 10 calendar days before your requested write date. If you live within Canada or the United States and are requesting an examination to be written at an established Athabasca University Approved Invigilation Centre, you must request your examination 20 calendar days before your requested write date. If you live outside of Canada and the United States and are requesting an examination to be written at an established Athabasca University Approved Invigilation Centre, your request must be received 30 calendar days before your requested write date. If you are requesting to write your examination using an invigilator who is not established as an Athabasca University Approved Invigilator, your request must be received 60 calendar days before your requested write date. To request an examination, follow the steps below. 1. Review the “Examinations and Grades” section of the current Athabasca University Calendar. 2. Arrange for a time to write your examination with one of Athabasca University’s Examination Centres or with an invigilator. For a list of Examination Centres, see the website http://www.athabascau.ca/registrar/invignet.php If you would like to use an invigilator who has not been approved by the Office of the Registrar, you may propose their approval by filling in the appropriate details on the online Examination Request Form. Keep in mind that invigilators may charge a fee, for which you will be responsible. 3. Complete and submit the online Examination Request Form. If you do not have access to the Internet, fill out the Examination Request Form 20


you received from the Office of the Registrar, and submit it by fax (780.675.6174), or in person or by postal mail to Examination Services, Office of the Registrar, at Athabasca University, Athabasca. Note: To minimize the time required to process your application, be sure that you provide all of the information requested on the form, and that you write legibly. 4. Confirm that your invigilator has received the examination package before you arrive to write your examination. Take picture identification and your student number with you when you go to the examination site. After you have written an examination, please be patient while you wait for the result. Examinations rarely reach our central offices in less than five days, and a ten-day lapse from when the examination is written to its arrival in Athabasca is not unusual. Chemistry examinations are normally marked within twenty-four hours of receipt, and your tutor is informed of the mark before your next tutor night. Writing an examination one day and calling the course professor a day or two later does not expedite the marking process. For security reasons, examinations cannot be returned to students, nor can the professor enter into detailed discussions of specific examination questions. After each of your examinations is corrected, some written comments will be sent to you. Your tutor will also receive a copy of these comments, and you should discuss the issues raised with your tutor on the first suitable occasion.

Supplemental Examinations Students who are dissatisfied with their grade on any examination, or who obtain less than the required passing grade, may write a supplemental examination. Only one supplemental is permitted per examination. The higher of the two grades received will be recorded as the official grade. Note that there is a fee for each supplemental examination.

Appeals Appeals to examination or assignment grades should be discussed first with your tutor or instructor. For the correct procedure, see “Student Code of Conduct and Right to Appeal” in the current Athabasca University Calendar or available through your myAU portal.

Organic Chemistry I

21

Student Conduct and Appeals Three policies in particular govern the conduct of students of Athabasca University: ● the Non-Academic Misconduct Policy, ● the Academic Misconduct Policy, and ● the Student Academic Appeals Committee Policy, also known as the

Academic Appeals Policy. You are responsible for reading these policies carefully, as they affect your studies and your role as an Athabasca University student. Links to these policies are provided though your myAU portal. Click on the “Student Services” tab near the top of your myAU web page. Links to the policies affecting students are given in the “Policies and Standards” section at the bottom right-hand side of the Student Services page. We encourage you to read all of the policies on this list. Note: All of the assignments you submit for this course must be original work completed especially for the course. The use of assignments completed for other courses, or assignments from other students, both are considered cheating, and will be penalized as such.

Intellectual Indebtedness Students enrolled in any Athabasca University course are considered to be responsible scholars, and are therefore expected to adhere rigorously to the principles of intellectual honesty. Plagiarism is a form of intellectual dishonesty in which another’s work is presented as one’s own, and, as will any form of academic misconduct, plagiarism will be severely penalized. Depending on the circumstances, penalties may involve rejection of the submitted work; expulsion from the examination, the course or the program; or legal action. Students sometimes commit plagiarism inadvertently. To avoid doing so, make certain that you acknowledge all your sources—both primary and secondary—in a full and consistent manner. All direct quotes (quotations, however short, from an original work), indirect quotes, paraphrased passages, ideas, images, and tabular and statistical information that you use from other sources (including electronic sources) must be documented using an acceptable citation style. There are three conventional ways of acknowledging your sources: in-text citations, footnotes, or end-notes. We prefer that you use in-text citations, combined with a full bibliography presented at the end of the essay. The in-text citation must give the name of the author, the date of publication, and the page on which the cited material appears (Doe, 1997, p. 60). The bibliographic entry must provide at least the author’s last name, first name or initial, the date of publication, the title of the work, the place of publication and the publisher. 22


Transcripts A student can request an official transcript by completing a paper “Transcript Request” form, by writing to the Office of the Registrar, by appearing at the Office of the Registrar in person, or by using the secure online request form. For instructions on making an online request, see http://www.athabascau.ca/registrar/OROShelp.php?page=transcriptRequest Only the student whose transcript is being issued may make the request, and a paper request must bear the student’s signature. No partial transcripts are issued. The student’s entire record is shown on each transcript. Most institutions and agencies require that official transcripts be sent directly from Athabasca University. Please allow a minimum of ten working days for the receipt of a transcript. Consult the current edition of the Athabasca University Calendar for further information about transcripts.

Transferring Credit If you wish to transfer credit to another institution, contact the Office of the Registrar at Athabasca University. Remember, however, that transfer of credit is determined by the receiving institution. If you plan to transfer credit for this course to another institution, we suggest you get an agreement, in writing, from that institution. This agreement is usually called a “letter of permission.”

Applying for Extensions If you are unable to complete this course within the six-month course contract period, you may apply for and purchase up to three, two-month extensions. Note that extension request forms must be received by the Office of the Registrar a minimum of one month before the end of your course contract. Requests for second and third extensions must be received by the Office of the Registrar a minimum of one month before the expiry of the previous extension. Consult the online Athabasca University Calendar for more information about obtaining extensions.

Organic Chemistry I

23

24


Sample Examinations On the following pages you will find sample examinations that will help you prepare for your midterm examination and your final examination. We have included such questions in this manual so that you may obtain a better idea of the length of a normal Athabasca University chemistry examination. Short answers for a majority of the questions are given at the end of the sample examinations.

Organic Chemistry I

25

26


Sample Midterm Examination The midterm examination is two (2) hours long. In the actual examination, you may not consult your books or notes; however, you may use a calculator or slide rule. You will also be provided with a periodic table and a set of 1 H NMR chemical shifts and infrared stretching frequencies, as needed. 1. Provide the complete IUPAC name for each of the following compounds:

a.

b.

c.

Organic Chemistry I

27

2. Provide structures for each of the following compounds: a. 3-ethyl-1-methyl-1,3-cycloheptadiene

b. 3,3,7-trimethyl-5-(2-methylpropyl)nonane

c. 3-cyclobutyl-1,5-hexadiene

28


3. For each of the compounds below, assign the appropriate R or S configuration to each of the atoms labeled with an asterisk.

* N+

a. Me

Et

b. * Cl H H Me c. *

*

d. D

H

4. Provide concise definitions for any (four) of the following terms. Be sure to make it clear which four are to be considered for grading, otherwise the first four for which answers are provided will be evaluated. a. torsional strain

b. chirality center

c. conformation

Organic Chemistry I

29

d. activation energy

e. electrophile

f. polarizability

g. substitution reaction

5. For each of the following molecules, provide a structure that satisfies the specified condition: a. The enantiomer of this cycloalkene:

Me

Me

30


b. A stereoisomer of the following compound that has a different melting point:

HO 2 C

CO 2 H

c. An alkyne that yields the following compound on treatment with Li metal in liquid ammonia:

d. A constitutional isomer of the following compound that yields a single product on treatment with hydrochloric acid in ether solvent:

Organic Chemistry I

31

6. For each of the following pairs of structures, circle the one that is most stable. Provide a brief justification for your decision. a.

b.

and

and

●

●

c.

d.

32

and

and


7. Compound A is a clear colourless liquid with a molecular formula of C8 H8 . On treatment with excess H2 gas in the presence of Lindlar catalyst, Compound B (C8 H12 ) was recovered as the only product. Treatment of Compound B with O3 followed by zinc dust furnished the two products shown below. Provide structures for compounds A and B, and briefly justify your answers. H

H

H

H

and O

Organic Chemistry I

O

O

O

33

8. Consider the hypothetical transformation of starting material C into product D. The ∆G○ for the process is 20 KJ/mol and the ∆G‡ is 30 KJ/mol.

Energy GGGGGGGGGGGGGGGA

a. Complete the potential energy diagram for the conversion of C to D in the grid provided below. Note that the position of C is provided for you, and that each division along the vertical axis corresponds to 10 KJ/mol.

C

} 10 KJ/mol C GGGGGGGGGGGGGGGGGGGGA D b. Is the forward reaction endergonic, exergonic, or neither? Justify your decision.

c. Calculate the ∆G‡ for the hypothetical reverse process.

d. Which species would you expect to most closely resemble the transition state: C or D? Justify your decision.

34


9. Provide a complete “arrow-pushing” mechanism for the following transformation that includes any reactive intermediates. Account for the fact that only a single alkyl bromide is formed in the reaction.

HBr ether

Organic Chemistry I

CH3 Br

35

10. Identify which of the following two chair conformers of chlorocyclohexane is more stable, and support your argument with a thorough discussion including an analysis (with drawings) of Newman projections along the C1—C2 and C1—C6 bonds of each conformer. H 6

1

6

Cl 2

H

2 1

Cl

36


11. Provide three additional reasonable resonance structures for each of the following compounds: O a.

O ●●

N

O b.

O c.

Organic Chemistry I

N

N

37

12. Complete five of the following chemical equations by providing the missing starting material, reagent(s) or product(s) as necessary. Be sure to indicate stereochemistry where appropriate. Remember to clearly indicate which reaction you do not want graded, otherwise the first five equations for which answers are given will be graded. a. KMnO4 , H3 O+ GGGGGGGGGGGGGGGGGGGA

and

Note: There are two organic products.

b. H2 SO4 , H2 O GGGGGGGGGGGGGGGGGA HgSO4

c.

38

O Cl

1. OsO4 GGGGGGGGGGGGGGGGA 2. NaHSO3 , H2 O


d.

e.

f.

Organic Chemistry I

HBr (1 equivalent) GGGGGGGGGGGGGGGGGGA Ether

H2 , Pd/C GGGGGGGGGGGGGA

GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGA

39

13. Outline a synthetic strategy for the multi-step preparation of any two) of the following compounds from the indicated organic starting material. For each synthetic step, indicate the required reagent(s) as well as any organic intermediate. Be sure to indicate which problem you do not want graded: otherwise the first two problems for which an answer (correct or otherwise) is provided will be graded.

OH a. prepare

OH

from Br

Br

CO2 H b. prepare

40

from


c. prepare

Organic Chemistry I

from

41

42


Sample Midterm Examination—Answer Key

1. a. 3-methyl-1,4-cyclohexadiene b. (4Z)-5-methyl-4-octen-1-yne or (4Z)-5-methyloct-4-en-1-yne c. 1-cyclohexyl-3-ethynylcyclohexane 2. a.

b.

c.

3. a. S b. S c. S d. S 4. Definitions of all terms are given in the textbook glossary. 5. a. Me

Me b. HO 2 C

CO 2 H

c. d.

Organic Chemistry I

43

6. a. More highly substituted.

b.

●

Tertiary alkyl radicals are more stable than secondary ones, owing to the ability of the alkyl substituents to stabilize electron-deficient centres via induction.

c. Less ring strain.

d. The E isomer is more stable, primarily as a result of slightly higher steric repulsion in the Z isomer.

7. A.

B. The ozonolysis products directly implicate B as having the above structure, since this is the only possible structure with the formula C8 H12 that could possibly furnish the indicated products. The reaction with H2 in the presence of Lindlar catalyst is a classic test for alkyne functionality: no other functionality (including alkene) will react under these conditions. The fact the molecular formula increases by 4 hydrogen atoms as A converts to B indicates that 2 equivalents of H2 gas are being consumed and that therefore A is a diyne. Since the central carbon in the 7-carbon chain in compound B does not have a hydrogen atom attached to it, it must be the double bond in the molecule that was originally also a double bond in A: as a result, the other two double bonds (those at the ends of the 7-carbon chain) must have arisen from triple bonds in A, which allows one to arrive at the above structure for A.

44


8. a.

Energy GGGGGGGGGGGGGGGA

........... ... ...... .... ......... . .. ... . . . . . ........

D

C

} 10 KJ/mol C GGGGGGGGGGGGGGGGGGGGA D b. Endergonic: ∆G○ is positive (the product is higher in energy than the starting material). c. From the graph, it is apparent that ∆G‡ for the reverse process is the difference between ∆G‡ for the forward process and ∆G○ . 30 KJ/mol − 20 KJ/mol = 10 KJ/mol. d. D: According to the Hammond postulate, the transition state most closely resembles the species which is most similar in energy. In an endothermic process, this is the product. 9.

: :

H—Br

_

: Br : +

CH3 Br

The reason that only a single alkyl bromide is formed lies in the nature of the carbocation formed in the first step: it is tertiary. The alternative carbocation (shown below) would be primary, and thus would be too high in energy to form.

+

Organic Chemistry I

45

H 6

10.

6

1

H

2

Cl

1

Cl

2

more stable H R

Newman projection: C1–C6

R

H H

R

Cl

R

H !

H H

Newman projection: C1–C2

H

Cl H

R

H

H

R

R

Cl

H

R

H

!

Cl

The conformer on the left, with the Cl atom in an equatorial position, is the most stable. In the case of this conformer, the Newman projections (C1—C6 and C1—C2) reveal that, in each case, the R-groups are “gauche” with respect to one another, but the bulky Cl atom (on C1) is “anti” to the R group on the other atom. In the case of the less stable conformer, the Newman projections (C1—C6 and C1—C2) reveal that the R-groups are in each case still “gauche” with respect to one another, but now there exists a second unfavourable “gauche” interaction between the Cl atom on C1 and the R group on the adjacent atom (C2 or C6). 11. Any of the following are acceptable:

+

+

: O

+

N

:

_

:O :

:

: 46

+

_

:O :

O +

N

N

_

:O :

O

N

:

N

O

_

:O :

O

:

:O :

O

O +

N

:

_

:

:

a.

_


_

:

:

:

_

:O :

_

:O :

:O : +

b.

+

+N

N

CO2 H 12. a.

b.

c.

:

+

_

:O : :

N

_

:O : :

c.

:

:O :

:

_

:

:

+

N

N

N+

O and

Cl

HO HO Br

d.

e.

f.

Organic Chemistry I

CH2 I2 , Zn/Cu

47

13. a.

OH

KOH

1. OsO 4

ethanol

2. NaHSO3 , H 2 O

OH

b. Br KMnO4 , H3 O+ GGGGGGGGGGGGGGGGGGGA

KOH GGGGGGGGGA ethanol

CO2 H + CO2

c.

Br2 GGGGGGA CH2 Cl2

48

Br

Br

2 KOH GGGGGGGGGGGA ethanol

H2 GGGGGGGGGGGGGGGA Lindlar catalyst


Sample Final Examination The final examination is three (3) hours long. In the actual examination you may not consult your books or notes; however, you may use a calculator or slide rule. You will also be provided with a periodic table and a set of 1 H NMR chemical shifts and infrared stretching frequencies, as needed. 1. Provide the complete IUPAC name for each of the following compounds:

a.

OH

NO2 b. Cl

c.

Organic Chemistry I

49

2. Provide structures for each of the following compounds: a. m-chloroacetophenone

b. 3,3-dibromocyclooctene

c. (R)-3-benzyldecane

3. Identify which of the two protons, Ha or Hb , will have the higher chemical shift, and explain why. O H3 CO CH3 Ha

50

Hb


4. Draw the structure of an organic compound that satisfies the given spectral data: a. a compound with the formula C4 H9 Cl with only one signal in its 1 H NMR spectrum: a singlet at 1.62 ppm.

b. a compound with the formula C3 H7 Br with the following 1 H NMR signals: A septet at 3.79 ppm (integrating for 1H), and a doublet at 1.31 ppm (integrating for 6H).

c. a compound with the formula C7 H5 N with the following IR signals: 3066 cm−1 (medium, sharp), 2230 cm−1 (strong, sharp), 1572 cm−1 (medium, sharp), 1492 cm−1 (medium, sharp).

d. a compound with the formula C6 H8 which gives rise to two signals (ignoring coupling/splitting) in its 1 H NMR spectrum, and does not absorb UV light in the 200-400 nm range.

Organic Chemistry I

51

5. Using any combination of words, diagrams and chemical equations, explain the following observations. a. Although 2-butyne possesses a C—C triple bond, no signal is observed between 2400 cm−1 and 2100 cm−1 in the IR spectrum of this compound.

2-butyne

b. Friedel-Crafts alkylation is a poor method for the preparation of butylbenzene.

butylbenzene

c. During the preparation of a Grignard reagent, it is important that the glassware and chemicals are completely dry.

52


6. a. Complete the molecular orbital diagram for the cyclopentadienyl cation by placing the electrons in the appropriate orbitals. ψ4

ψ5

ψ2

ψ3

cyclopentadienyl cation

Energy

+

ψ1 b. Complete the molecular orbital diagram for the cyclopentadienyl anion by placing electrons in the appropriate orbitals. ψ4

ψ5

ψ2

ψ3

cyclopentadienyl anion

Energy

−

ψ1 c. Identify which of the two compounds (the cation or the anion) is the more stable, and carefully explain why this is so. A complete answer should include a discussion of the two MO diagrams completed above.

Organic Chemistry I

53

7. Compound A (C8 H10 ) is a clear colourless liquid with a boiling point of 139○ C. Compound A is unreactive towards Br2 in the absence of light, but slowly reacts when exposed to sunlight to form HBr as a by-product. As well, compound A is unreactive towards H2 in the presence of a number of different catalysts, including Pd/C and Lindlar catalyst. On the other hand, Compound A reacts with KMnO4 to form Compound B (C8 H6 O4 ). The 1 H NMR spectrum of B contains three signals, all having the same integration. Provide structures for A and B.

54


8. a. From the following assortment of dienes, circle the one which you would expect to be the most suitable for use in a Diels-Alder reaction. Briefly justify your choice.

b. From the following group of dienophiles, circle the one that you would expect to be most reactive in a Diels-Alder reaction. Briefly justify your choice. H

CO2 CH3

H

H

H

CH3

H

CO2 CH3

H

H

H

CH3

c. Draw the product you would obtain from the Diels-Alder reaction between the diene and dienophile you selected above. Be sure to indicate any product stereochemistry where appropriate.

Organic Chemistry I

55

9. Provide complete arrow-pushing mechanisms for the following transformations. a.

56

Br2 GGGGGGA H2 O

Br OH


b.

Organic Chemistry I

CH3 Cl GGGGGGGGGGA AlCl3

57

10. In each of the cases below, circle the most appropriate compound. Justify your choice. a. Which of these solvents is better for promoting an SN 2 reaction? Explain your decision. O or H

CH3 OH

N(CH3 )2 DMF

Methanol

b. Which of these substrates will undergo SN 1 substitution more rapidly?

or Br

Br

c. Which of these anions is more likely to promote an elimination reaction instead of a substitution reaction? CH3 CH2 S−

or

CH3 CH2 O−

d. Which of these anions reacts more rapidly as a nucleophile in an SN 2 reaction, if all other conditions are identical? Br−

58

or

I−


11. Provide concise definitions for any four of the following terms. Be sure to make it clear which four are to be considered for grading, otherwise the first four for which answers are provided will be evaluated. a. McLafferty rearrangement

b. prochiral

c. Grignard reagent

d. LUMO

e. heterocycle

f. downfield

g. exothermic

Organic Chemistry I

59

12. Identify the number of signals you would expect to observe in the 1 H NMR of each of the compounds below. Also, for each compound, sketch the 1 H NMR signal arising from the proton labeled with an asterisk, taking care to estimate the chemical shift of the indicated proton and to represent clearly the expected splitting pattern. ∗

H

H

a. H3 C

NO2 H

O

H

H∗

b. O

O

H∗ c. O

60


13. Complete ten of the following chemical equations by providing the missing starting material, reagent(s) or major organic product(s) as necessary. Be sure to indicate stereochemistry where appropriate. Be sure to make it clear which reaction you do not want graded, otherwise the first ten equations for which answers are given will be graded. Br a.

SO3 GGGGGGGA H2 SO4

NBS

Organic Chemistry I

b.

GGGGGGGA

c.

NaNH2 GGGGGGGGGGGA

61

d.

OH

H3 PO4 GGGGGGGGGGA 120○ C

Br e.

Na+ − CN GGGGGGGGGGGGGA DMSO

f.

g.

62

1. O3 GGGGGGGGGGGA 2. Zn/H3 O+

2 Br2 GGGGGGGGA CH2 Cl2


h.

O GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGA

O

Br i.

j.

Organic Chemistry I

NaNH2 GGGGGGGGGGGA NH3 200○ C

H2 GGGGGGA Pd/C

63

O Cl2 GGGGGGA FeCl3

k.

l.

64

Br

Mg GGGGGGGA ether


14. Outline a synthetic strategy for the multi-step preparation of the following compounds from the indicated organic starting material. For each synthetic step, indicate the required reagent(s) as well as any organic intermediate. NO2 a. prepare

from CO2 H

b. prepare

from D

Organic Chemistry I

OH

65

66


Sample Final Examination—Answer Key

1. a. 2,3,5-trimethylphenol b. 1-chloro-2-nitrobenzene c. 2-ethyl-5-methyl-1,5-hexadiene O 2. a.

Cl

Br

Br

b.

c.

H

CH 2 Ph O

3. H3 CO CH3 Ha

Hb

:

Hb has the higher chemical shift. It is ortho to the carbonyl group, which is electron-withdrawing both by induction and by resonance. These same effects which deactivate the ortho and para positions for electrophilic aromatic substitution also deshield protons in these positions raising the chemical shift.

H 3 CO

H 3 CO +

CH3 Ha

Organic Chemistry I

_

:O :

O

Hb

Ha

CH3 Hb

67

4. a.

Cl

Br b.

c.

N

d.

5. a. 2-butyne is a symmetrical alkyne: each of the triply-bonded carbons bears a methyl group and, as a result, the C—C triple bond is completely non-polar. Stretching this bond (with IR radiation) will not therefore result in a change in the bond dipole (or molecular dipole) and so will result in no absorption in the indicated region of the IR spectrum. b. Friedel-Crafts alkylation is a poor method for the preparation of butylbenzene because it would require the use of a primary alkyl halide, such as 1-chlorobutane or 1-bromobutane. Such alkyl halides do not directly form stable carbocations and often undergo carbocation rearrangements, making them unsuitable for use in Friedel-Crafts chemistry. c. Grignard reagents are extremely basic and reactive towards water and any other compounds containing —OH groups. If the glassware or chemicals are wet, the Grignard reagent, if formed, will immediately be protonated (and thus destroyed) by the water.

6. a.

+

Ψ4

Ψ5

Ψ2

Ψ3 Ψ1

cyclopentadienyl cation

_

energy

b.

cyclopentadienyl anion

Ψ4

Ψ5

Ψ2

Ψ3 Ψ1

c. The anion is considerably more stable than the cation. The six valence electrons completely fill the degenerate orbitals Ψ2 and ψ3 ,

68


imparting unusual stability on the anion: the anion is thus aromatic. On the other hand, the cation has only four valence electrons, which result in partially filled degenerate orbitals ψ2 and ψ3 . As a result of this, the cation is said to be anti-aromatic and is extremely unstable. CO2 H

7.

CO2 H A

B

8. a.

This is the only one of the dienes that can attain the required s-cis conformation required for Diels-Alder chemistry. Furthermore, the third diene is not conjugated, and is thus doubly unsuitable for Diels-Alder chemistry. b. H

CO2 CH3

H

CO2 CH3

This dienophile will work best in Diels-Alder chemistry as it is the one bearing the electron-withdrawing groups: such groups enhance the reactivity of a dienophile.

H

c.

H CO 2 CH 3 CO 2 CH 3

Organic Chemistry I

69

:

: :

: :

9. +

Br :

: Br — Br :

:

:

a.

O H

H

Br

Br +

OH

:

OH

:

:

B

: AlCl 3

_

Cl — AlCl 3

H3 C

: :

b.

+

H

: Cl : — CH 3

H

:B

+

70


10. a. DMF is the better solvent for promoting SN 2 reactivity. Although both solvents are quite polar, DMF is aprotic whereas methanol is protic. The protic solvent, methanol, stabilizes nucleophiles, rendering them less reactive and therefore slowing the rate of SN 2 reactions. On the other hand, the aprotic solvent does not suffer from this disadvantage.

O or H

CH3 OH

N(CH3 )2

DMF

Methanol

b. The rate of the SN 1 substitution is determined by the rate of cation formation,which is in turn determined by cation stability. The alkyl bromide on the left would form the more stable carbocation (it is tertiary) and therefore is more rapid in SN 1 substitution chemistry.

or Br

Br

c. The anion on the right is the more basic and therefore the more likely to induce an elimination reaction.

CH3 CH2 S−

or

CH3 CH2 O−

d. Although both anions are good nucleophiles, iodide is larger and more polarizable, and is therefore the one which will react more rapidly in an SN 2 process. Br−

or

I−

11. Definitions for all of the terms are located in the glossary in the course textbook.

Organic Chemistry I

71

∗

H

H

12. a. H3 C

NO2 H

3 signals

7.3 ppm

H The indicated proton should appear as a doublet near 7.3 ppm.

O

H∗

b.

1 signal

3.7 ppm

O The indicated proton should appear as a singlet near 3.7 ppm.

c.

O

H∗

4 signals O

4.1 ppm

The indicated proton should appear as a quartet near 4.1 ppm.

Br

Br

13. a.

and SO3 H

HO3 S

Br b.

c.

72

C−..

+

Na


d.

CN e.

O f. O Br Br g. Br Br

h.

NH2 i.

j.

O k.

l.

Organic Chemistry I

Cl

MgBr 73

14. a.

KMnO4 , H3 O+ GGGGGGGGGGGGA

CH3 Cl, AlCl3 GGGGGGGGGGGA

HNO3 , H2 SO4 GGGGGGGGGGGA

NO2

CO2 H

CO2 H

b. H3 PO4 GGGGGGGGGGA OH

74

HBr GGGGGGGA Ether

Br

Mg GGGGGGGA Ether

D2 O GGGGGGGGA MgBr

D
