TOFAs (A grade, Segezha Pulp-and-Paper Com- bine, Joint-Stock Company) were additionally purified by vacuum distillation, with the fraction boiling at.
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 12, pp. 2178–2179. © Pleiades Publishing, Ltd., 2008. Original Russian Text © A.V. Kurzin, A.N. Evdokimov, O.S. Pavlova, V.B. Antipina, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 12, pp. 2068–2069.
BRIEF COMMUNICATIONS
Esters of Amylose, Cellulose, and Tall Oil Fatty Acids A. V. Kurzin, A. N. Evdokimov, O. S. Pavlova, and V. B. Antipina St. Petersburg State Technological University of Vegetable Polymers, St. Petersburg, Russia Received May 14, 2008
Abstract—The possibility of preparing amylose and cellulose esters by esterification and acylation with chlorides of tall oil fatty acids was examined. DOI: 10.1134/S1070427208120288
Esters of carbohydrates and higher fatty acids (HFAs), the so-called liposaccharides, are promising and valuable nonionic surfactants used in various branches of industry and in medicine [1]. Polysaccharide esters form a particular group of liposaccharides. The main procedures for their preparation are based on acylation with HFAs under the conditions of acid or base catalysis, and also on ester interchange of alkyl esters of acids with polysaccharides [1–4]. A promising renewable source of fatty acids is tall oil, a by-product from kraft pulp production. The main components of tall oil fatty acids (TOFAs) are unsaturated С18 acids: oleic, linoleic, and linolenic [5]. A search for new applications of tall products is a topical problem of pulp-and-paper and resin industry. Previously, we have prepared liposaccharides from sucrose [6], xylitol [7], and tall oil fatty acids. The goal of this study was to prepare TOFA esters of amylose and cellulose. Use of strong Brønsted acids as acylation catalysts leads to formation of dark tarry products. A more efficient synthetic route to polysaccharide esters is the reaction of activated polymers with acid chlorides in the presence of tertiary amines. Chlorides of higher unsaturated acids are usually prepared by treatment of the acids with phosphorus halides or thionyl chloride, but side processes occur in the latter case. For the experiments, we chose phosphorus trichloride, which is successfully used in synthesis of chlorides of higher fatty unsaturated acids, including TOFAs [8]. Among the catalysts reported in the literature for esterification of carbohydrates with HFAs, a particular
place is occupied by anhydrides and chlorides of acetic acid derivatives (methoxyacetic, chloroacetic, trifluoroacetic acids). Positive results have also been obtained with free trichloroacetic acid used as catalyst (impeller). The degree of substitution of the reaction product was calculated from the difference between the saponification number and acid number. For the amylose ester prepared with TOFA chlorides, it was 0.38, and for the ester prepared using trichloroacetic acid, 0.45. The low acid numbers (less than 1 mg KOH/g product) show that the product hardly contains any amount of starting fatty acids. The appearance of new ester bonds is also confirmed by comparison of the IR spectra of the starting amylose and its esterification products. Absorption bands characteristic of stretching vibrations of ester C=O groups (1730 cm–1) and of double bonds in hydrocarbon residues of TOFAs (1680–1620 cm–1) appear in the IR spectra, whereas bands of the reagents used, including C–Cl stretching vibration bands (800– 600 cm–1), are absent. The polymers obtained are structurally similar to surfactants widely used today for stabilization of dispersions and control over rheological properties (Emulsan etc.) [9]. EXPERIMENTAL TOFAs (A grade, Segezha Pulp-and-Paper Combine, Joint-Stock Company) were additionally purified by vacuum distillation, with the fraction boiling at 170–205°С/1 mm Hg collected. Bleached coniferous pulp (Kotlas Pulp-and-Paper Combine, Joint-Stock Company) was disintegrated to separate fibers. TOFA
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ESTERS OF AMYLOSE, CELLULOSE, AND TALL OIL FATTY ACIDS
chlorides were prepared by the reaction of the acids with phosphorus trichloride according to [7]. In our study we used edible-grade amylose and dehydrated trichloroacetic acid (chemically pure grade). Pyridine (chemically pure grade) was dried over KOH and distilled. The acid and saponification numbers were determined by the standard procedures [10]. The IR spectra of the esters were recorded on a Shimadzu FTIR8400S spectrophotometer from Nujol mulls. Esters of polysaccharides and TOFAs were prepared as follows. (1) A mixture of 20 g (0.12 mol) of the polysaccharide (cellulose was preliminarily kept in 50 ml of pyridine for 2 days in a flask with a tightly ground-in stopper), 80 ml of pyridine, and 100 ml of toluene was stirred for 20 min. To this mixture, 150 ml (0.5 mol) of TOFA chlorides was added, and the mixture was heated with a reflux condenser at 55°C for 8 h. Then 100 ml of methanol was added, the mixture was filtered, and the precipitate was washed with methanol (2 × 50 ml) and petroleum ether (50 ml) and dried in air. (2) Trichloroacetic acid (210 g, 1.3 mol) was mixed with 105 ml (0.36 mol) of TOFAs, after which 50 g of pyridine was added. The mixture was stirred for 20 min. To this solution, 20 g (0.12 mol) of the polysaccharide was added (cellulose was preliminarily kept in 50 ml of pyridine for 2 days in a flask with a tightly ground-in stopper), and the mixture was heated with a reflux condenser at 40°C for 8 h. Then 150 ml of methanol was added, the mixture was filtered, and the precipitate was washed with two portions of a methanol–hexane mixture (1 : 1, 50 ml) and dried in air. The resulting amylose esters are weakly colored solid amorphous substances, and cellulose esters are pale yellowish fibrous materials.
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CONCLUSION Polysaccharides can be acylated with tall oil fatty acids or acid chlorides in the presence of pyridine or with the free acids in the presence of trichloroacetic acid. REFERENCES 1. Zhoglo, F.A., Zhirosakhara (Poluchenie, svoistva, primenenie) (Liposaccharides: Preparation, Properties, Use), Moscow: Meditsina, 1975. 2. Heinze, T., Liebert, T., and Koschella, A., Esterification of Polysaccharides, Berlin: Springer, 2006. 3. Grass, A.T. and Feuge, R.O., J. Am. Oil Chem. Soc., 1962, vol. 39, no. 1, pp. 19–24. 4. Ioannidis, O.K., Pogosov, Yu.L., and Aikhodzhaev, B.I., in Khimiya i fizikokhimiya prirodnykh i sinteticheskikh polimerov (Chemistry and Physical Chemistry of Natural and Synthetic Polymers), Tashkent: Fan, 1964, issue 2, pp. 60–65. 5. Kogan, V.B. and Trofimov, A.N., Poluchenie karbonovykh kislot na osnove drevesiny (Preparation of Carboxylic Acids from Wood), Moscow: Lesnaya Prom– st., 1977. 6. Kurzin, A.V., Evdokimov, A.N., Pavlova, O.S., and Antipina, V.B., Zh. Prikl. Khim., 2007, vol. 80, no. 2, pp. 345–346. 7. Kurzin, A.V., Evdokimov, A.N., Pavlova, O.S., and Antipina, V.B., Khim. Rast. Syr’ya, 2008, no. 1, pp. 151–152. 8. Wang, S.-F., Furuno, T., and Cheng, Z., J. Wood Sci., 2001, vol. 47, no. 3, pp. 470–475. 9. Holmberg, K., Jönsson, B., Kronberg, B., and Lindman, B., Surfactants and Polymers in Aqueous Solution, Chichester: Wiley, 2003. 10. Gurova, T.A., Tekhnicheskii kontrol’ proizvodstva plastmass i izdelii iz nikh (Technical Monitoring of Production of Plastics and Articles Thereof), Moscow: Vysshaya Shkola, 1991.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 81 No. 12 2008
