Patent GB-793507-A (GB)
Title: Novel ketones and a process for the manufacture thereof
IPC: C11B9/00
Filed: 1956-09-14
Abstract: The invention comprises ketones of the general formula <FORM:0793507/IV (b)/1> wherein each of the symbols R1, R2, R3 and R4 represents a hydrogen atom or an acyclic hydrocarbon radical containing less than eight carbon atoms, and the manufacture thereof by heating a mixture of an alcohol of the general formula <FORM:0793507/IV (b)/2> and its acetoacetate ester at a temperature of between about 130 DEG  and 160 DEG  C.  Preferably, equal weights of the reaction components are heated together at a temperature between 150 DEG  and 155 DEG  C. until the evolution of carbon dioxide ceases.  In Example (1), 4-[21-methyl-51 - isopropenylcyclopenten - (11) - yl] - butanone-(2) is prepared by heating equal weights of racemic 3,7 - dimethyl - octen - (6) - yn - (1)-ol-(3) and its acetoacetate ester.  In a similar manner, 4 - [21, 51 - dimethyl - 51 - isopropenylcyclopenten - (11) - yl] - butanone - (2), 4 - [21-methyl - 51 - [buten - (211) - yl - (211)] - cyclopenten - (11) - yl] - butanone - (2), 4 - [21 - methyl - 51 - [411 - methyl - penten - (211) - yl-(211)] - cyclopenten - (11) - yl] - butanone - (2), 4 - [21 - methyl - 31 - ethyl - 51 - isopropenylcyclopenten - (11) - yl] - butanone - (2), 4 - [21-methyl - 31 - allyl - 51 - isopropenylcyclopenten-(11) - yl] - butanone - 2, 4 - [21 - methyl - 31 - propargyl - 51 - isopropenylcyclopenten - (11)-yl - (11)] - butanone - (2), 4 - [21 - methyl - 31-ethyl - 51 - [buten - (211) - yl - (211)] - cyclopenten-(11) - yl - (11)] - butanone - (2) and 4 - [21 - methyl - 31 - allyl - 51 - [buten - (211) - yl - (211)]-cyclopenten - (11) - yl - (11)] - butanone - (2) are obtained by heating respectively the acetoacetate esters of 3,6,7-trimethylocten-(6)-yn-(1) - ol - (3), 3,7 - dimethyl - nonen - (6) - yn-(1) - ol - (3), 3,7,9 - trimethyldecen - (6) - yn-(1) - ol - (3), 3,7 - dimethyl - 4 - ethylocten - (6)-yn - (1) - ol - (3), 3,7 - dimethyl - 4 - allylocten-(6) - yn - (1) - ol - (3), 3,7 - dimethyl - 4 - propargylocten - (6) - yn - (1) - ol - (3), 3,7 - dimethyl - 4 - ethylnonen - (6) - yn - (1) - ol - (3) and 3,7 - dimethyl - 4 - allylnonen - (6) - yn - (1) - ol - (3) with the corresponding parent alcohols.  The products are characterized by conversion to the semicarbazone, phenylsemicarbazone and/or 2 : 4-dinitrophenylhydrazone.  Starting materials.  Alcohols of the second general formula above are obtained from ketones of the general formula <FORM:0793507/IV (b)/3> by the action of an alkali-metal acetylide and hydrolysis. Acetoacetate esters of these alcohols are obtained by condensing them with diketene.  The preparation of the starting materials of the last seven examples is described in detail, including the following preliminary steps: The ketones of the foregoing general formula wherein R1 = methyl or isopropyl and R2 = R3 = R4 H are manufactured from 3-methyl-penten-(1)-ol-(3) and 3,5-dimethyl-hexen-(1)-ol-(3) respectively by treatment with concentrated hydrochloric acid to form respectively 1-chloro-3-methylpenten - (2) and 1 - chloro - 3,5 - dimethylhexene-(2), condensing these with ethyl sodio-acetoacetate and hydrolysing and decarboxylating the products.  The ketones wherein R4 = ethyl, allyl or propargyl and R1 = R2 = R3 = H are obtained by the action of ethyl, allyl and propargyl bromides respectively on the sodio-derivative of 1,1-dimethylpropen-(2)-yl-(1) acetoacetate, followed by decarboxylation.  The ketone wherein R1=methyl, R4= allyl and R2=R3=H is prepared similarly by condensing the sodio-derivative of 3-methyl-penten - (1) - yl - (3) acetoacetate with allyl bromide, followed by decarboxylation.  The ketone wherein R1=methyl, R4=ethyl and R2=R3=H is prepared by condensing ethyl-methyl-vinyl-carbinol with diketene, condensing the sodio-derivative of the resulting acetoacetate ester with ethyl bromide and decarboxylating the product.