Patent GB-438810-A (GB)
Title: Improvements in the purification of hydrocarbons
IPC: C07C7/17
Filed: 1934-06-02
Abstract: In the process of treating hydrocarbon oils such as benzol and cracking products containing dienes with maleic acid or maleic acid anhydride as described in the parent Specification, the maleic acid is added in several portions and the condensation products thus formed with the different dienes are separated after each addition. Crude benzol or benzine obtained by low temperature carbonization or thermal conversion of gaseous hydrocarbons may be treated.  Cracking benzine is mixed at ordinary or slightly elevated temperatures with a small amount of maleic acid and the addition product is separated by cooling, distillation, or conversion into the calcium salt.  Two further amounts of maleic acid are separately added and the corresponding products obtained in the form of calcium salts.  The insoluble salts obtained are treated to yield the respective acids consisting of bicycloheptene carboxylic acid (first stage), and methyl cycloheptene o-carboxylic acid (second stage) and may be further purified by extraction with hot ligroin in which the methyl derivative only is soluble.  The aqueous filtrates obtained are treated with copper sulphate or lead acetate to obtain the addition compounds with acyclic dienes formed in the last stage. Hydrocarbons obtained by thermal conversion of gaseous hydrocarbons are treated with 20 portions of maleic acid anhydride and the addition products separated at each stage by distillation and conversion into the calcium salts.  The first 10 products contain compounds of cyclo- and methyl cyclo-pentadiene.  The final 10 products contain acyclic addition compounds, for example, of isoprene and fulvene in the earlier stages and of piperylene in the final stages.  The latter addition product was purified by treating the neutralized aqueous filtrate obtained after removing the insoluble calcium salts, with copper acetate and liberating the free acid by treating the resulting copper salt with sodium bisulphate.ALSO:In the process of treating mineral oils containing dienes with maleic acid or maleic anhydride as described in the parent Specification, the maleic acid is added in several portions and the condensation product thus formed with the different dienes are separated after each addition.  Crude benzol or benzine obtained by low temperature carbonization or thermal conversion of gaseous hydrocarbons may be treated.  Cracking benzine is mixed at ordinary or slightly elevated temperatures with a small amount of maleic acid and the addition product is separated by cooling, distillation or conversion into the calcium salt.  Two further portions of maleic acid are separately added and the corresponding addition products obtained in the form of calcium salts.  The calcium salts obtained are separately treated to yield the respective acids consisting of bicycloheptene carboxylic acid (first stage) and methyl cycloheptene o-carboxycylic acid (second stage), and may be further purified by extracting with hot ligroin in which the methyl derivative only is soluble.  The aqueous filtrates from the calcium salts are treated with copper sulphate or lead acetate to obtain the addition compounds formed with acyclic dienes from the final stage.  Hydrocarbons obtained by the thermal conversion of gaseous hydrocarbons were treated with 20 portions of maleic acid anhydride and the addition products separated at each stage by distillation and conversion into the calcium salts.  The first 10 products contained compounds of cyclo- and methylcyclo pentadiene.  The final 10 products contained acyclic additional compounds, for example of isoprene and fulvene in the earlier stages and of piperylene in the final stages.  The latter addition product was purified by treating the neutralized aqueous filtrate obtained after removing the insoluble calcium salts, with copper acetate and liberating the free acid by treating the resulting copper salt with sodium bisulphate.