Process for making aromatic aldehydes

Abstract

Alkyl aromatic compounds are converted to alkyl aromatic aldehydes by a carbonylation reaction. The carbonylation catalyst can be a high boiling point carbonylation catalyst which allows for the separation of the aldehyde product by selective volatilization. Alternatively, the carbonylation catalyst can be selected from perfluoroalkyl sulfonic acids having 2 to 18 carbon atoms, perfluoroether sulfonic acids having 2 to 18 carbon atoms, BF3.(ROH)x wherein R represents CH3 or H and X is a number within the range of from 0.2 to 2, GaBr3, GaCl3, TaF5, NbF5, and NbBr5, with the proviso that when the catalyst is TaF5, NbF5, or NbBr5, then the reaction takes place in the absence of added HF. Preferably, all of the carbonylation reactions take place in the absence of added HF. The alkyl aromatic aldehydes can be oxidized to form an aromatic acid. A mixed xylene feed stock can be converted to a mixture of diemthylbenzaldehydes and then oxidized to form trimellitic acid without the need to separate the xylene or dimethylbenzaldehyde isomers.

Description

Background of the invention [0001] 1. field of invention [0002] This invention relates to a process for the preparation of alkylaromatic aldehydes and aromatic acids from alkylaromatic compounds and to catalysts for use therein. [0003] 2. related technology [0004] The carbonylation of alkylaromatic compounds to form aldehydes can be carried out by a reaction generally known as the Guttman-Corch reaction. In 1897 Gatterman and Koch described the direct carbonylation of various aromatic compounds with carbon monoxide and hydrogen chloride in the presence of aluminum chloride and cuprous chloride (Gatterman, L. and Koch, J.A., "Chem.Ber .)", 30, 1622 (1897)). The reaction was later expanded to include other Lewis acids. In addition, it was found that cuprous chloride can be omitted if the CO pressure is increased. This reaction is reviewed in Olah, G.A., "Friedel-Crafts and Related Reactions", Wiley-Interscience, N.Y., Vol. III, 1153 (1964). [0005] For example, US...

AI Technical Summary

Problems solved by technology

However, this step also chemically changes the catalyst which destroys the availability of the catalyst

This separation leading to single use of the catalyst makes the process commercially unattractive because of the high cost of regeneration and recycling of the catalyst