Alcohols acetylations, acetic anhydride

Phlein was acetylated by acetic anhydride in pyridine solution. The crude product was purified by dissolving the dry substance in as small an amount of chloroform as possible, centrifuging to separate impurities, and precipitating the acetate by the dropwise addition of alcohol. After the process had been repeated a few times, a constant-rotating product resulted. 

Addition of lithiated heterocycles to aldonolactones yields carbon-linked nucleosides (56). Thus, the reaction of 2,3 5,6-di-O-isopropylidene-L-gu-lono-1,4-lactone (9b) or 2,3-O-isopropylidene-D-ribono-l,4-lactone (16a) with various lithiated heterocycles gave gulofuranosyl derivatives 53a-g or ribofuranosyl derivatives 54b,c. Gulonolactols 53a-g and ribonolactols 54b,c were acetylated with acetic anhydride in pyridine to yield their acetyl derivatives. The stereochemistry of compounds 53a-g and 54b,c was discussed in terms of the Cotton effect of circular-dichroism curves of the ring-opened alcohols formed upon reduction by sodium borohydride. The configuration at C-l of 53g was proved by means of X-ray analysis (57,58). 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

Bromination of ketone 58 could not be accomplished. The alcohol was therefore acetylated with acetic anhydride in pyridine at rt, which gave 87% of a 9 1 mixture of 59 and enol acetate 60. The enol acetate was the... 

Cyclization of enone (9) in hexane with boron trifluorideetherate in presence of 1,2-ethanedithiol, followed by hydrolysis with mercury (II) chloride in acetonitrile, yielded the cis-isomer (10) (16%) and transisomer (11) (28%). Reduction of (10) with lithium aluminium hydride in tetrahydrofuran followed by acetylation with acetic anhydride and pyridine gave two epimeric acetates (12) (32%) and (13) (52%) whose configuration was determined by NMR spectroscopy. Oxidation of (12) with Jones reagent afforded ketone (14) which was converted to the a, 3-unsaturated ketone (15) by bromination with pyridinium tribromide in dichloromethane followed by dehydrobromination with lithium carbonate and lithium bromide in dimethylformamide. Ketone (15), on catalytic hydrogenation with Pd-C in the presence of perchloric acid, produced compound (16) (72%) and (14) (17%). The compound (16) was converted to alcohol (17) by reduction with lithium aluminium hydride. 

Acetates of fatty [1] and polyhydric [2] alcohols, phenols [3] and chlorophenols [4] have been studied. Fell and Lee [3] described a GC method for the determination of polyhydric phenols in urine, which, having been extracted, were acetylated with acetic anhydride in the presence of 4-dimethylaminopyridine. According to these authors this substance shows much stronger catalytic effects than does the usually used pyridine. The derivatives are formed rapidly and quantitatively even in very dilute solutions. In the absence of the catalyst, bifunctional phenols provide more than one GC peak. Slightly polar OV-210 is recommended for the separation of phenol acetates, but analysis on nonpolar OV-101 leads to tailing, probably as a consequence of insufficient deactivation of the column. 

This method involves hydrolysis of the protein sample with a cation exchange resin in the hydrogen form, reduction of the sugars to the corresponding alcohols, acetylation with acetic anhydride in pyridine, and gas chromatography of the acetylated alcohols. 

Alcohols, phenols, thiols, and amines can be acetylated with acetic anhydride in the presence of montmorillonite K10 under mild conditions.239 Octyl acetate was obtained in 1 hr from 1-octanol, in 96% yield, using K10 at room temperature. Peracetylation of sugars, such as glucose, has been done in similar fashion in 92-99% yields.240... 

Esters, Ethers, and Related Derivatives of Alcohols.— Although acetylation with acetic anhydride-pyridine is one of most familiar reactions, the detailed mechanism does not seem to have been elucidated.Spectroscopic detection of the acetylpyridinium ion resulting from the equilibrium ... 

Esters. The catalyst promotes transesterification, for example, the acetyl group from EtOAc to alcohols. Acetic anhydride can be used as acylating agent. 

The ketolactam (233) was prepared from the lactamol (232) by heating in a mixture of methanol and concentrated hydrochloric acid. The ketolactam was reduced with lithium aluminum hydride in refluxing dioxane to afford the desired exoalcohol (234) and its epimer (235) in a 1 1 ratio. These epimers were separated by chromatography on alumina. The undesired epimer (235) was converted by Jones oxidation to the corresponding ketone (236), which was reduced with sodium in refluxing absolute alcohol to yield alcohols 234 and 235 in a more favorable 7 3 ratio. The exoalcohol 234 was acetylated with acetic anhydride in pyridine, and the product was hydrolyzed by heating with dilute methanolic potassium hydroxide to obtain the -acetate alcohol (237). The latter was... 

DMAP acts as an efficient acyl transfer agent, so that alcohols resistant to acetylation hy Acetic Anhydride-Pyridine usually react well in the presence of DMAP. Sterically hindered phenols can be converted into salicylaldehydes via a benzofurandione prepared by DMAP catalysis (eq 2). ... 

The results, however, are inconclusive, because combustion analyses fail to match the theoretical composition for poly(methallyl alcohol). It is impossible to teU to what extent the reduction takes place. Inconclusive results are also obtained in similar reductions of poly(methyl acrylate) in mixtures of tetrahydrofiuan and benzene. When a product of such reduction is acetylated with acetic anhydride in pyridine as follows ... 

The use of qualitative information alone is not suf cient to correctly characterize an essential oil, and quantitative data are of extreme importance. Classical methods are generally focused on chemical groups and the assessment of quantitative information through titration is widely applied, for example, for the acidimetric determination of saponi ed terpene esters. Saponi cation can be performed with heat, and in this case, readily saponi ed esters are to be investigated, in the cold, and afterward, the alkali excess is titrated with aqueous hydrochloric acid thereafter, the ester number can be calculated. A further test is the determination of terpene alcohols by acetylating with acetic anhydride part of the acetic anhydride is consumed in the reaction and can be quanti ed through titration of acetic acid with sodium hydroxide. The percentage of alcohol can then be calculated. The latter method is applied when the alcoholic constituents of an essential oil are not well known in case these are established, the oil is saponi ed, and the ester number of the acetylated oil is calculated and used to estimate the free alcohol content. 

While the alkylation of compound 207 with diazoalkanes clearly indicates its enol character, some other reactions reveal that it can also behave as a typical (3-ketoester. For example, reduction with sodium borohydride in aqueous methanol yielded the saturated alcohol (208) which after chromatography was isolated as a crystalline substance in 30% yield. Acetylation with acetic anhydride in pyridine gave 3-acetox-ycepham (209) from which the acetic acid was eliminated upon treatment with triethylamine in methylene chloride, affording the 3-H cephalosporin (210). 

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