Acylation of Starch with Vinyl Acetate in Water

Mörmann, Werner; Al‐Higari, Mohamed

doi:10.1002/star.200300238

Cited by 34 publications

(25 citation statements)

References 5 publications

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“…It has been reported that polysaccharides such as starch, cyclodextrins, or cellulose can be successfully esterified in homogeneous or heterogeneous conditions by reaction with vinyl esters 23–28. More recently, we showed that lignocellulosic materials such as wood can be easily esterified in mild conditions by this method 29–31.…”

Section: Introductionmentioning

confidence: 89%

Acetylation of Cellulose Nanowhiskers with Vinyl Acetate under Moderate Conditions

Çetin

Tingaut

Özmen

et al. 2009

Macromolecular Bioscience

168

107

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A novel and straightforward method for the surface acetylation of cellulose nanowhiskers by transesterification of vinyl acetate is proposed. The reaction of vinyl acetate with the hydroxyl groups of cellulose nanowhiskers obtained from cotton linters was examined with potassium carbonate as catalyst. Results indicate that during the first stage of the reaction, only the surface of the nanowhiskers was modified, while their dimensions and crystallinity remained unchanged. With increasing reaction time, diffusion mechanisms controlled the rate, leading to nanowhiskers with higher levels of acetylation, smaller dimensions, and lower crystallinity. In THF, a solvent of low polarity, the suspensions from modified nanowhiskers showed improved stability with increased acetylation.

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Section: Introductionmentioning

confidence: 89%

Acetylation of Cellulose Nanowhiskers with Vinyl Acetate under Moderate Conditions

Çetin

Tingaut

Özmen

et al. 2009

Macromolecular Bioscience

168

107

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“…The starch peaks (d 3-5.5 ppm) are broad and overlapping [10]. This feature hampers the DS determination by NMR, and therefore a peracetylation procedure to substitute all of the remaining OH groups with acetate groups was applied [8,10,11]. The 1 H-NMR spectrum of a typical peracetylated starch laurate is shown in Fig.…”

Section: H-and 13 C-nmr Analysesmentioning

confidence: 99%

“…Recently Mormann et al [8] explored the possibility of using vinyl esters and particularly vinyl acetate as reagents for the preparation of starch esters. Their re-search focused on the synthesis of starch acetates and only two examples of a reaction with a higher fatty acid vinyl ester were reported.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Higher Fatty Acid Starch Esters using Vinyl Laurate and Stearate as Reactants

et al. 2008

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This paper describes the synthesis of long-chain fatty esters of corn starch (starch laurate and starch stearate) with a broad range in degree of substitution (DS = 0.2422.96). The fatty esters were prepared by reacting the starch with vinyl laurate or vinyl stearate in the presence of basic catalysts (Na 2 HPO 4 , K 2 CO 3 , and Na acetate) in DMSO at 1107C. The yellowish products were characterized by 1 H-, 13 C-NMR and FT-IR. The DS of the products is a function of the carbon number of the fatty acid chain, vinyl ester to starch ratio and the type of catalyst. When performing the reactions using Na 2 HPO 4 as the catalyst, the DS for the starch laurate compounds is higher than for the corresponding starch stearates. For low vinyl ester to starch ratios, an increase in the vinyl ester concentration leads to higher product DS values. At higher ratios, the DS decreases, presumably due to a reduction of the polarity of the reaction medium. K 2 CO 3 and Na acetate are superior catalysts with respect to activity compared to Na 2 HPO 4 and products with DS values close to 3 were obtained.

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“…However, the degree of substitution (DS) is still low and the catalyst is expensive too. Very recently, two reports appeared in the literatures that use a base catalyzing acetylation of starch [13] and sucrose [14] with vinyl acetate in water. Because vinyl acetate is not sensible and miscible with water, the reaction mixture forms two layers reducing loss of acylating agent due to reaction with water, which is a major problem encountered for acetylation with acetic anhydride.…”

Section: Introductionmentioning

confidence: 99%