Acetic acid, reaction with alkoxides

The oxidation of 3H- 1,2-benzodiazepines (90 R = Hor Me) with MCPB A gave both (91) and (92). The former have proved useful as precursors for 3-substituted 1,2-benzodiazepines via treatment with bases or acids. Thus (91) on reaction with alkoxides (R -) and CH(C02Et)2 gave respectively (93 X = OR1) and (93 X = CH(C02Et)2) in ca. 70% yields, and treatment with hydrogen chloride and with acetic acid gave (93 X = C1) and (94) respectively (78CPB1896). 

Metal alkoxo-acetates can be formed by the reaction of acetic acid (HOAc) with metal alkoxides [156-158], Whereas the addition of HOAc decreases the gel time of silicon alkoxide systems [159], the reverse effect is observed for Ti(OR)4 and Zr(OR)4 [113,158]. To understand this behavior in acetic acid-modified Ti(OR)4 systems, Livage and coworkers [160] and Sanchez and coworkers [148] have performed careful experiments combining XANES, C NMR, IR, and EXAFS. ... 

Hydrolysis of TEOS in various solvents is such that for a particular system increases directiy with the concentration of H" or H O" in acidic media and with the concentration of OH in basic media. The dominant factor in controlling the hydrolysis rate is pH (21). However, the nature of the acid plays an important role, so that a small addition of HCl induces a 1500-fold increase in whereas acetic acid has Httie effect. Hydrolysis is also temperature-dependent. The reaction rate increases 10-fold when the temperature is varied from 20 to 45°C. Nmr experiments show that varies in different solvents as foUows acetonitrile > methanol > dimethylformamide > dioxane > formamide, where the k in acetonitrile is about 20 times larger than the k in formamide. The nature of the alkoxy groups on the siHcon atom also influences the rate constant. The longer and the bulkier the alkoxide group, the lower the (3). 

Zinc chloride is a Lewis acid catalyst that promotes cellulose esterification. However, because of the large quantities required, this type of catalyst would be uneconomical for commercial use. Other compounds such as titanium alkoxides, eg, tetrabutoxytitanium (80), sulfate salts containing cadmium, aluminum, and ammonium ions (81), sulfamic acid, and ammonium sulfate (82) have been reported as catalysts for cellulose acetate production. In general, they require reaction temperatures above 50°C for complete esterification. Relatively small amounts (<0.5%) of sulfuric acid combined with phosphoric acid (83), sulfonic acids, eg, methanesulfonic, or alkyl phosphites (84) have been reported as good acetylation catalysts, especially at reaction temperatures above 90°C. 

Factor b above is discussed in Sections II, B, 1 II, B, 4 and II, C. A hydrogen-bonded structure such as 221 can account for the facile reaction of 5-bromouracil or for the unique, so-called hydrolyzability of carboxymethylthio-azines (237). The latter may also react via the intramolecular mechanism indicated in 136. The hydrogen-bonded transition state 238 seems a reasonable explanation of the fact that 3,4,6- and 3,4,5-trichloropyridazines react with glacial acetic acid selectively to give 3-pyridazinones while other nucleophiles (alkoxides, hydrazine, ammonia, or sulfanilamide anion) react at the 4- and 5-positions. In this connection, 4-amino-3,5-dichloro-pyridazine in liquid hydrazine gives (95°, 3hr, 60%yield)the isomer-... 

Alternatively, 232 was obtained by cyclocondensation of 233 with phenacyl halides in the presence of acetic acid and subsequent reaction of the formed triazinophthalazine with alkoxides or sec-amines (89FES29). 

Most often in these processes, compounds such as acetic acid, acetylacetone (acac, 2,4-pentanedione), or amine compounds are employed, since these compounds readily react with alkoxides.4M877 A typical reaction involves the formation of new chemical species that (hopefully) possess physical and chemical characteristics that are more attractive in terms of solution stability and film formation behavior. An example reaction between a metal alkoxide and acetic acid is shown below ... 

Some reactions of 2,2 -bipyridine /V-oxides have been reported. The l,T-dioxide is nitrated readily to 4,4 -dinitro-2,2 -bipyridine 1,T-dioxide. ° ° °" 2,2 -Bipyridine 1-oxide is also nitrated in the 4 position. The nitro groups in 4,4 -dinitro-2,2 -bipyridine l,T-dioxide are reactive, being replaced by chlorine with concentrated hydrochloric acid," by bromine with acetyl bromide, by hydroxyl with dilute sulfuric acid, and by alkoxy groups with sodium alkoxides. Some of the dialkoxy derivatives are useful catalysts for the oxidation of aromatic compounds. The dinitro dioxide is deoxygenated to 4,4 -dinitro-2,2 -bipyridine with phosphorus trichloride in chloroform, and other substituted l,T-dioxides behave similarly, but with phosphorus trichloride alone, 4,4 -dichloro-2,2 -bipyridine results. The dinitro dioxide is reduced by iron powder in acetic acid to 4,4 -diamino-2,2 -bipyridine, whereas 4,4 -dichloro-2,2 -bipyridine l,T-dioxide is converted to its 4,4 -diamino analogs with amines. Related reactions have been described. ... 

Oxidation of TIOAc with bromide in acetic acid gives Tl(OAc)Br2,321 but as with the alkoxides such reactions have apparently not been investigated in detail. Thallium(I) carboxylates have found considerable application in organic synthesis.274,275,322... 

As indicated in Scheme 27, indoles may be alkylated by their acid-catalyzed reaction with alcohols. Similarly, r-butylation of pyrroles has been effected by the acid-catalyzed reaction with t- butyl acetate (B-77MI30502), and the diarylmethylation of 1-methylpyrrole from the acid-catalyzed reaction with the chromium trichloride complex of the diarylcarbinol has been described (78JA4124). The alkylation of indoles by alcohols in the presence of the aluminum alkoxide and Raney nickel appears to be efficient for the synthesis of 3-substituted indoles, but is less successful in the alkylation of 2-methylindole (79JHC501). The corresponding isopropylation of pyrrole produces 2,5-diisopropylpyrrole and 1-isopropylpyrrolidine, as the major products (79JHC501). 

Alcohols can also be prepared from support-bound carbon nucleophiles and carbonyl compounds (Table 7.4). Few examples have been reported of the a-alkylation of resin-bound esters with aldehydes or ketones. This reaction is complicated by the thermal instability of some ester enolates, which can undergo elimination of alkoxide to yield ketenes. Traces of water or alcohols can, furthermore, lead to saponification or transesterification and release of the substrate into solution. Less prone to base-induced cleavage are support-bound imides (Entry 2, Table 7.4 see also Entry 3, Table 13.8 [42]). Alternatively, support-bound thiol esters can be converted into stable silyl ketene acetals, which react with aldehydes under Lewis-acid catalysis (Entries 3 and 4, Table 7.4). 

Evidence for such reactions in methylmethacrylate polymerizations was obtained by termination of polymerizations with acetic acid followed by measurements of methanol formed (119, 120). Fig. 6 shows typical results obtained. It is assumed that the methanol found corresponds to lithium methoxide in the reaction mixture. Some methanol might in fact be produced only in the termination reaction from pseudo-cyclized species (cf. p. 82). In addition the tertiary alkoxides formed by attack of the initiator or growing polymer chains on the carbonyl group of the monomer might not eliminate lithium methoxide immediately but would do so on termination with acetic acid. In any case much of the methanol formed corresponds to actual alkoxide in the reaction mixture and the results give a minimum value of the concentration of species inactive in polymerization. For brevity it will be referred to as lithium methoxide. 

Chloroacetic Acid (ClCHiCOOHf. [CAS 79-11-8 J. Chloroacelic acid can be synthesized by the radical chlorination of acetic acid, treatment of trichloroethylene with concentrated H S04. oxidation of 1.2-dichloro ethane or chloroaceialdehyde. amine displacement from glycine, or chlorination of ketene. It behaves as a very strong monobasic acid and is used as a strong acid catalyst for diverse reactions. The Cl function can be displaced in base-catalyzed reactions. For example, it condenses with alkoxides to yield alkoxyacetic acids CICH COOH... 

Another approach to sol-gel PZT precursors involves the reaction of alkoxide mixture with glacial acetic acid [1442, 1790], Lead acetate and titanium... 

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