Abstract

OLEFI~ condensation with formaldehyde, known as the Prins reaction, has again at tracted the attention of scientists. Several reactions belong to this group, a common feature of which is at present the use of the same raw materials (olefin and formaldehyde) , while the reactions themselves greatly differ both in method and results. The Prins reaction attained technical importance in the production of isoprene from isobutylene and an aqueous formaldehyde solution from 1,3-dioxane with mineral acids as catalysts. Of the various Prins reactions [1, 2] thermal condensation has been least studied although, judging from literature data, even this method could be suitable for processing unsaturated hydrocarbon waste products into technically important esters and alcohols and perhaps even higher dienes. Thermal condensation is carried out by two methods: either in a medium consisting of a mixture of acetic anhydride and acetic acid, normally at 140-200 ° for 56 hr [2-5], or in pure acetic anhydride at 180-200 ° for several hours (usually five) and only in exceptional cases does condensation take longer [6, 7]. According to literature data, the same reaction products are formed in both cases, but the ratio of certain components varies. In the main reaction formaldehyde is simultaneously combined with olefin with the transfer of the olefin double bond and esterification of the alcohol formed. Acetic anhydride acts as a catalyst and as a reagent in esterification. In addition to alkenol acetates, alkenediol diacetates were also found in the reaction products, formed during the secondary reaction, i.e. further condensation of alkenol acetates with formaldehyde and acetic aiahydride. The acetate part is a mixture of several compounds. In addition to isomeric esters with different positions of the double bond (since the double bond can move in different directions in the initial olefin), esters of different carbon skeletal structure were also found in the mixture [2, 5]. Agami pointed out tha t on heating olefin with acetic anhydride and acetic acid without formaldehyde, the initial olefin is only isomerized

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