Starch acetals production

Using acetic acid, starch acetates are formed, which are used as film-forming polymers for pharmaceutical products, and as the polymer in biodegradable packing-foam peanuts. Starch acetates have a lower tendency to create gels than unmodified starch. 

Glucose, glycerol, sucrose, starch, acetate, malate and lactate were examined for the effect of carbon sources on the hydrogen production and the effects of light intensity were also examined under the different irradiances, such as 0, 3, 7, 15, 30, 50 and 110 klux/m2, by adjusting the distance between the light source and the samples of Rb. sphaeriodes KD 131 cultures. 

Tarvainen, M., Peltonen, S., Mikkonen, H., Elovaara, M., Tuunainen, M., Paronen, P, Ketolainen, J., Sutinen, R. (2004). Aqueous starch acetate dispersion as a novel coating material for controlled release products. J. Contr. Re/., 96(1), 179-191. 

CNC SOFT XXX is exceptionally versatile as it is compatible with anionic, cationic or nonionic substances. It is compatible with resins, catalysts and optical bleaches also acrylic resins, polyvinyl acetate emulsions and starches. The product may be applied by padding or exhaust methods. 

Amyloid.—When treated with concentrated sulphuric acid cellulose dissolves and undergoes hydrolysis. If the solution is diluted with water a gelatinous product is obtained which gives the blue color with iodine characteristic of starch. This product is known as amyloid. When boiled in the dilute acid the amyloid is hydrolyzed and dextrin and finally glucose are obtained. Concentrated hydrofluoric acid and phosphoric acid also dissolve cellulose. With glacial acetic acid in the presence of acetic anhydride and sulphuric acid cellulose yields acetyl derivatives indicating its alcoholic character. From the products of this reaction the acetate of a di-saccharose is obtained. 

It should be observed that slight depolymerization or incomplete acetylation of the starch acetate molecule leads to products possessing a much wider degree of solubility. For example, at low acetyl values (0-26%), starch acetates are said to be water-soluble. -" However, if the starch molecules are undegraded, it is probable that the water-soluble range does not extend to products containing more than fi-15% acetyl groups. 

Paralleling their film-forming properties, these amylose triacetates can be molded into strong, tough plastics, but the amylopectin triacetates yield only very brittle products. Similarly, Mullen and Pacsu have shown that whole starch acetate produces clear, transparent, molded pieces which, however, are brittle. 

C, whereas the com starch derivative only turned brown at this temperature. Further allylation led to diallyl ethers.748-752 For this purpose, an acetone solution of starch acetate in a 50% solution of NaOH containing allyl bromide was boiled or heated in an autoclave at 80 °C. These procedures were then improved by using either butanone and KOFI753 or 1,4-dioxane and NaOH.754 Di-O-allyIstarch is a soft, gummy product that is soluble in most of organic solvents except for aliphatic hydrocarbons. This solubility is lost after exposure of diallyl starch to air.748 It can also be hardened by the addition Co(II) octanoate or Co(II) naphthenate.755... 

Reduction of acetals with NaBH4 was reported,1369 but no applications of the products were given. Crosslinking of starch acetals with epichlorohydrin and similar compounds was also described.1370 A urea-formaldehyde-starch copolymer reacted with hydrogen peroxide and Cu(II) catalysts, thereby producing a starch solution with improved stability of viscosity.1371... 

Acylated starch can be copolymerized to yield materials for films, lacquers, and fibers.2111 Starch acetate copolymerized with epichlorohydrin was extruded to give cold-water swelling products with a high degree of friability.2112 Epichlorohydrin-crosslinked starch has been acylated with 2,3-di-O-benzoyl-L-threaric anhydride.2113 The reaction proceeded either in /V,/V-dimethy 11 ormam ide or in toluene, and the non-crosslinked product has also been reported.2114... 

The development of waxy corn species offered better potentials for the production of starch derivatives in high demand in the world market. The technology for the production of waxy starch-acetate has been elaborated. 

The reaction of polysaccharides ivith aldehydes to give cross-linked products has been known and exploited industrially for some time. Starch acetals may also be prepared by a method that does not give rise to cross-links and involves treatment of starch with a cyclic vinyl ether, 3,4-dihydro-2H-pyran, to give a tetrahydropyran-2-yl derivative (16). At low levels of substitution, the acetals are water-soluble, at... 

Methyl-, hydroxyethyl-, hydroxypropyl-, and carboxymethyl starches, starch acetates, succinates, alkenyl succinates (Fig. 2), adipates, and phosphates, are all well-known products. Furthermore, special derivatives have also been prepared, such as vinyl-, silyl-, ° or propargyl starches, as reactive intermediates for fiirther fime-tionalization. Unusual substitution patterns can also be established by highly selective deacetylation with alkyldiamines and subsequent introduction of such functional groups as sulfates. From die analytical point of view, the most important aspects are stability under alkaline (mediylation) and acidic or Lewis-acidic (depolymerization) conditions, reactivity (such as migration, rearrangement, further substitution or addition reactions, or any intramolecular reaction), and polarity (lipophilic/hydrophilic, ionic/nonionic, acidic/basic). These properties mainly determine the analytical... 

High DS starch acetates are used to create brittle films and molded products. These have had little application, due to the economic superiority of cellulose acetates. In general, specific gravity and melting temperature both decrease with an increase in acetylation (45). Highly acetylated starches above 15% acetyl content (DS approximately 0.7) are soluble in water at 50° to 100°C and insoluble in organic solvents. When the acetyl content reaches 40% (DS approximately 2.5), the derivatized starch is soluble in aromatic hydrocarbons, ketones, and glycol ethers. 

Of the esters, starch phosphate is produced by reaction with phosphorus oxychloride, polyphosphates, or metaphosphates a cross-bonded product results. Total degree of substitution is determined by measuring the phosphorus content, and the mono- to disubstitution ratio can be calculated by potentio-metric titration. Allowance is made for the natural phosphorus content of the starch. Treatment of starch with acetic anhydride produces starch acetate, which has improved paste stability over native starch. The acetyl group is very labile, and hydrolyses readily under mild alkaline conditions. When a known amount of alkali is used, the excess can be titrated and the ester function measured. This is not specific, however, and a method based on an enzymatic measurement of the acetate has been developed in an ISO work group. The modified starch is hydrolyzed under acidic conditions, which releases acetic acid and permits filtration of the resulting solution. Acetic acid is then measured by a commercially available enzyme test kit. Both bound and free acetyl groups can be measured, and the method is applicable... 

The most common reaction of esterification is starch acetylation. The oldest methods of starch acetylation consisted mainly in heating starch with acetic acid anhydride in pyridine or ice-cold acetic add. This method of acetylation was applied by, among others, Twele [22, 61, 73]. Contemporarily, starch acetates are usually produced as a result of reaction run in a water suspension by exposing starch to acetic acid anhydride. All of the hydroxyl groups could react with acetic anhydride. One of the three possible products is shown in Figure 7.1. 

Zi ba T, Szumny A, Kapelko M. Effect of production method of starch acetate on its amylolysis. Przem Chem 2011 90 (3) 470 74. (in pohsh). 

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