Acetic anhydride methyl acetate homologation

Thus, the overall acetaldehyde selectivity approaches 98%. The utility of methyl acetate as an alternative feedstock has been previously illustrated by the reported carbonylation to acetic anhydride ( ) and homologation ( ) to ethyl acetate via reaction with synthesis gas. 

For both reactions a RhCl3/CH3l/TPO catalyst in acetic acid as reaction solvent affords propionic acid in more than 80 % yield according to the respective stoichiometries of Equations 12 and 13. Although acetic acid is present in excess in the reaction medium, it does not participate in the homologation as reactant. Only traces of propionic acid are produced in the absence of methyl acetate, ethyli-dene diacetate or acetic anhydride under our reaction conditions. Homologation of carboxylic acids has been reported by Knifton (10) to require more severe reaction conditions (220 °C, > 100 bar). 

In the future, there is no doubt that alcohols will play a major role not only as fuel components (70,71) but also as feed stocks for the syntheses of more complicated organic compounds (72). A great amount of research effort is presently directed to the economic conversion of CO and to methanol (73), and on homologation of methanol to higher alcohols (74). Conversion of synthesis gas from coal to acetic anhydride (75) through the intermediacy of methyl acetate (from methanol) will soon be a commercial reality. 

The mono- and poly-alkylated benzenes are treated using modifications of the above procedure. Monoalkylbenzenes are added to a preformed complex of acyl halides and aluminum chloride in carbon tetrachloride (Perrier modification). In this manner, the manipulation is easier, no tars are encountered, and the yields are improved (85-90%). The procedure shows no advantage, however, in the acylation of alkoxy- or chloro-aromatic compounds. The addition of benzoyl chloride to p-alkylbenzenes in the presence of aluminum chloride in cold carbon disulfide is a good procedure for making p-alkylbenzophenones (67-87%). The condensation of homologs of benzene with oxalyl chloride under similar conditions yields p,p -di alkylbenzophenones (30-55%). Polyalkylbenzenes have been acylated with acetic anhydride and aluminum chloride (2.1 1 molar ratio) in carbon disulfide in 54-80% yields. Ferric chloride catalyst has been used under similar conditions. Acetylation of p-cymene with acetyl chloride and aluminum chloride in carbon disulfide yields 2-methyl-5-isopropylaceto-phenone (55%). ... 

However, 70 hr at 200°C was necessary to convert 2-aminobenzonitrile in formic acid to quinazolin-4-one.193 Acetic anhydride formed the 2-methyl homolog under similar conditions, but higher anhydrides reacted very little.194... 

Alder route, was converted into the urethan (25) by a series of unexceptional steps. Arndt-Eistert homologation of (25) provided the carboxylic acid (26) which, upon treatment with acetic anhydride, readily gave the lactam (27). Introduction of a one-carbon unit into the aromatic ring was achieved with chloromethyl methyl ether, and further reductive and hydrolytic modification afforded the amino-alcohol (28). Osmium tetroxide oxidation of (28) yielded the stereoisomeric triols (29) (20%) and (30) (22%) which were separated and oxidized to ( + )-clivonine (31) and (+ )-clividine (32), respectively. 

If sodium carbonate is used instead of triethylamine, the yield of the product 237 (R = H) is reduced to 80% [146], In the case of 6-chloroisatoic anhydride the same reaction was carried out with additional boiling in acetic acid, and the homolog of compound 227, not containing a methyl substituent at position 1, was obtained [146]. 

Some alternative but related methods for the homologation of glycine have also been developed. Bis(diphenylphosphino)glycine methyl ester yields an enolate (189), when treated with potassium t-butoxide, which can be cleanly monoalkyl-ated with, for example, benzyl bromide. The phosphorus group is removed by acid hydrolysis. The oxazolin-5-ones (190), derived from A/ benzoyl-a-amino-acids and acetic anhydride, can be readily alkylated in the 4-position hydrolysis gives a,a-disubstituted JV-benzoyl-a-amino-acids. ... 

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