Process for making n-butyl esters from butadiene

Abstract

Process for making a butyl ester from butadiene, comprising (a) reacting butadiene with a saturated aliphatic monocarboxylic acid to form a mixture of n-butenyl and secondary butenyl esters, (b) separating the n-butenyl ester from the secondary butenyl ester, and (c) hydrogenating the n-butenyl ester separated in step (b) in the presence of a catalyst to the corresponding n-butyl ester.

Description

[0001]This is a continuation of PCT application No. PCT / GB99 / 03452, filed Oct. 19, 1999, the entire content of which is hereby incorporated by reference in this application.[0002]The present invention relates to a process for making n-butyl esters by reacting butadiene with a carboxylic acid in the presence of a Brønsted or Lewis acid catalyst to form the unsaturated ester which is subsequently hydrogenated to form the saturated ester.BACKGROUND OF THE INVENTION[0003]It is known that n-butyl esters such as n-butyl acetate can be produced by a number of routes. For instance, the hydroformylation of propylene in the presence of acetic acid is a method which gives a mixture of n-butyl acetate and iso-butyl acetate. This method however requires a source of syngas which increases capital costs. An alternative method is to react ethylene with vinyl acetate in the presence of an acid catalyst followed by the hydrogenation of the resultant unsaturated ester. A further method is the reaction...

AI Technical Summary

Benefits of technology

[0078]Two sequential reactions were carried out on the charge of 85 g of Amberlyst 15H® used in example 2 (ethyl acetate pre-washed), the catalyst between runs was washed with acetic acid in situ to remove residual material from the previous run in the sequential reactions. The charge of butadiene was 700 g and acetic acid was 3600 g for all three experiments.

[0079]sec-Butenyln-ButenylRuntimeacetateacetate4-Vinyl cyclohexeneHighers(Minutes)(% w / w)(% w / w)(% w / w)(% w / w)0001.390600.770.641.440.16901.010.771.440.251501.551.151.40.362102.241.621.370.532702.631.911.360.643303.322.441.360.863903.892.891.391.04

[0080]sec-Butenyln-Butenylacetateacetate4-Vinyl cyclohexeneHighersRuntime(% w / w)(% w / w)(% w / w)(% w / w)0001.390603.192.621.30.9904.133.551.261.321506.166.021.182.632107.447.891.143.772707.928.711.134.253308.399.561.14.963908.6310.181.075.43

[0081]Examples 2, 3 and 4 illustrate that an optimum balance exists between activity and selectivity, i.e. at higher temperatures the activity is increased at the expense of the reaction selectivity. The process optimum will vary with factors such as catalyst employed and feedstock costs.

[0082]The Amberlyst 15H® resin charge used in example 4 was re-used as described for examples 3 and 4 by washing in situ with acetic acid in between runs. The butadiene and acetic acid charge were kept substantially identical to that employed in example 2. Example 6 re-used the charge used in example 5.

[0083]sec-Butenyln-ButenylRuntimeacetateacetate4-Vinyl cyclohexeneHighers(Minutes)(% w / w)(% w / w)(% w / w)(% w / w)0001.390600.960.841.410.31901.341.11.510.41501.981.551.510.552102.441.891.440.712703.222.51.470.943303.722.911.441.143904.533.61.521.34

Problems solved by technology

This method however requires a source of syngas which increases capital costs.

In addition, all these methods rely on the use of either relatively expensive feedstocks such as ethylene and n-butanol or involve multiple reaction stages or expensive catalysts and separation stages.

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