| 摘要 |
Aliphatic tertiary olefins are separated from mixtures containing such olefins and primary and/or secondary olefins and/or other hydrocarbons by reacting the mixture with a carboxylic acid in the presence of polyphosphoric acid at between -20 DEG and +15 DEG C., separating the resulting esters and decomposing the esters at a raised temperature in the presence of a catalytic amount of a strong acid into the corresponding acids and tertiary olefins. Specified tertiary olefins are isobutylene, 2-methyl-1-butene, 2-methyl-2-butane, 2,3-dimethyl-1-butene, 2-methyl-1-pentene and 2-methyl-1-hexene or mixtures thereof.ALSO:Tertiary alkyl esters are prepared by reacting an aliphatic tertiary olefine with a carboxylic acid in the presence of polyphosphoric acid, defined as a solution of phosphorus pentoxide in commercial phosphoric acid, at between -20 and +15 DEG C. Tertiary olefines specified are isobutylene, 2-methyl-1-butene, 2-methyl-2-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene and 2-methyl-1-hexene or mixtures thereof. Carboxylic acids mentioned are aliphatic, alicyclic, aromatic and heterocyclic acids which contain one or more carboxylic acid groups and in some cases substituents such as chlorine, nitro, cyano, hydroxy, amino and keto groups. The polyphosphoric acid, preferably a phosphoric acid solution containing 20-90% phosphorus pentoxide, is suitably mixed with the carboxylic acid in proportions ranging from 10 : 1 to 1 : 10 and the olefine then fed in with cooling if desired under slightly elevated pressure. This method may be effected in a column, the reactants being fed into the base with agitation and product being removed from the top of the column. The process may be continuous or discontinuous and solvents, e.g. ethers or cyclic ethers may be employed. The ester after washing and drying may be purified by distillation in the presence of sodium bicarbonate. The process may also be used for separating tertiary olefines from primary and secondary olefines and other hydrocarbons by reacting the mixture with a carboxylic acid as above, separating the esters and decomposing them at elevated temperatures in the presence of a strong acid giving the tertiary olefine, or saponifying to yield tertiary alcohols. In examples there are converted (1) and (4) isobutylene into t-butyl formate, (2) methyl-2-butene into t-amyl formate, (3) 3-methyl-2-pentene into the formic acid ester of 3-methyl-pentanol-3, (5) isobutylene into t-butyl acetate, (6) isobutylene into t-butyl butyrate, (7) isobutylene into t-butyl propionate, (8) isobutylene into t-butyl a -methyl butyrate, (9) isobutylene into t-butyl trimethylacetate and (10) isobutylene into t-butyl benzoate. Specified heterocyclic carboxylic acids are nicotinic and isonicotinic acid. |
