Acetates, acid hydrolysis

Oxidants are occasionally added to the hydrolysis mixture to favor the removal of lignin. For instance, the co-feed of 02 or air appeared beneficial to the deligni-fication efficiency of a lime-catalyzed hydrolysis step [57]. Similar improvements are also reported for the co-feed of H202 to formic or acetic acid hydrolysis [58],... 

The synthesis of valsartan (2) by Novartis/Ciba-Geigy chemists is highlighted in Scheme 9.5. Biphenylbenzyl bromide 18 is converted to biphenyl acetate 19 in the presence of sodium acetate in acetic acid. Hydrolysis of 19 followed by Swern oxidation delivered the biphenyl aldehyde 20, which underwent reductive amination with (L)-valine methyl ester (21) to give biphenyl amino acid 22. Acylation of 22 with penta-noyl chloride (23) afforded biphenyl nitrile 24, which is reacted with tributyltin azide to form the tetrazole followed by ester hydrolysis and acidihcation to provide valsartan (2). [See Biihlmayer et al. (1994, 1995).]... 

The basic cellulose unit contains three hydroxyl groups. The triester cellulose triacetate forms when cellulose is reacted with glacial acetic acid. Hydrolysis removes some of the acetate groups to form a secondary ester, which averages about 2.4 acetyl groups per unit rather than three. The secondary ester is then dissolved in acetone and the solution ejected through a spinneret to form fibers. Cellulose acetate processed in this manner is referred to as acetate rayon, but it may be more commonly known by its trade name Celanese. 

Experiment 6.152 describes a synthesis of quinaldinic acid from quinaldine (2-methylquinoline). The method depends upon the reactive nature of the 2-methyl group in quinaldine which can readily be brominated using bromine in acetic acid. Hydrolysis of the resulting tribromo derivative by boiling with dilute sulphuric acid occurs smoothly to give the corresponding carboxylic acid in good yield. 

Cyanoketen dimethyl acetal Acid hydrolysis w 1968 Also general catalysis by acetic acid... 

Wober, W., Alaupovic, P. Studies on the protein moiety of endotoxin from Gram-negative bacteria. Characterization of the protein moiety isolated by acetic acid hydrolysis of endotoxin from Serratia marcescens 08. Eur J Biochem 19 (1971) 357-367. 

Amino-4 -acetamidodiphenylamine-4-arsinic acid forms irregular, flat needles, acetylation yielding 2 i -diacetamid()di2 lienyl-a iitte-4i-arsinic acid, which crystallises in fine, colourless needles from dilute acetic acid. Hydrolysis of the latter compound yields 2 4> -di-amiiiodiphenylamine-i-arsinic acid, crystallising in long, slender prisms. 

Benzylidene acetals, very fragile in an acidic medium, are hydrolysed by aqueous acetic acid or cleaved by hydrogenolysis. Selectivity can be observed in the hydrolysis of isopropylidene acetals. With compound 5.10, only the ring spanning positions 5 and 6 is hydrolysed by aqueous acetic acid. Hydrolysis of the acetal function which involves the anomeric oxygen requires heating in mineral acid (0.1 M) for a few hours, comparable conditions to those of hydrolysis of a glycoside. 

The stereochemical requirements for observation of intramolecular general acid catalysis seem quite severe - less effective participation is observed in the hydrolysis of 8-methoxymethoxy 1-naphthoic acid and none at all in the hydrolysis of (2-methoxymethoxyphenyl) acetic acid. Hydrolysis of 2-methoxymethoxy-3-methyl benzoic acid is quite strongly sterically accelerated [136] but this is also true of its specific acid-catalysed reactions. 

The initial step of methanol conversion is composed of carbonylation to methyl acetate and dehydration to DME in parallel (see scheme below). DME is successively carbonylated to form methyl acetate. Methyl acetate is further carbonylated to acetic anhydride, which is rapidly hydrolyzed to acetic acid. Hydrolysis of methyl acetate to acetic acid and methanol proceeded also on the carbon support. Thus, carbonylation of methanol proceeds through a set of parallel and series reactions that produce methyl acetate and DME as primary products with acetic acid as the ultimate product, according to following reaction pathways (32,33) ... 

Valenta et al. confirmed the structure by synthesis of a lyconnotine derivative (98). They converted the alkaloid to ketone CVII which was synthesized in an unequivocal fashion. Ketone CVII was derived from lyconnotine according to the following scheme. Hydride reduction of lyconnotine followed by catalytic reduction and subsequent acetylation gave the saturated diacetate CVIII which deactivated preferentially at the primary hydroxyl group. The hydroxy acetate was then converted to the bromide which underwent hydrogenolysis on treatment with Zn in acetic acid. Hydrolysis of the monoacetate and oxidation of the result-... 

Carboxylic acids Acetic acid Hydrolysis of anhydride... 

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