Preparation of 3,5-dimethylcyclohex-2-en-1-one
Alternative Names: 3,5-Dimethyl-2-cyclohexen-1-one; 3,5-Dimethylcyclohex-2-en-1-one; 2-Cyclohexen-1-one, 3,5-dimethyl-; 3,5-Dimethyl-2-cyclohexene-1-one;
Diethyl 2,4-diacetyl-3-methylpentanedioate liquefied by heating in a water-bath is poured into a mixture of 400 g of water and 100 g of concentrated sulfuric acid contained in a round litre flask provided with a long reflux condenser. The reaction-mixture is heated to lively boiling on a wire gauze; a few pieces of unglazed porcelain are placed in the flask to insure a regular ebullition. After about seven hours heating, the reflux condenser is replaced by an ordinary condenser, and steam is passed into the mixture until the distillate measures about 100 ml. The flask is heated by a free flame up to the boiling-point of its contents. The distillate is preserved in a well-closed vessel. On the second day the mixture is again heated for seven hours (with a reflux condenser, new porcelain scraps in the flask), and then 100 ml are again distilled off with steam. This is repeated on the third day, and finally steam is passed into the mixture until from a test portion of the distillate saturated with solid potassium carbonate no oil, or only a minute quantity, separates out. The three distillates in which the reaction-product is for the most part dissolved are now united. Solid potassium carbonate is added until it is no longer dissolved. For the success of the salting out, one must use anhydrous potassium carbonate as pure as possible. From the potassium carbonate solution a brownish red oily layer separates out: it consists of 3,5-dimethylcyclohex-2-en-1-one and alcohol. It is separated from the water solution in a dropping funnel, and the alcohol is distilled off. The residue is dried over calcium chloride and distilled from an ordinary fractionating flask. The portion going over between 200-215° C is collected separately. Boiling-point of the pure compound, 211° C. Yield, 15-20 g.
The practical methods of organic chemistry, by L. Gattermann, 177-178, 1909
3,5-Dimethyl-2-cyclohexen-1-one, 3,5-Dimethylcyclohex-2-en-1-one, 1123-09-7, 2-Cyclohexen-1-one, 3,5-dimethyl-, NOQKKFBBAODEHN-UHFFFAOYSA-N, 3,5-Dimethyl-2-cyclohexene-1-one, ST51038564, 2-Cyclohexen-1-one,5-dimethyl-, NSC845, AC1L23IS, AC1Q2QI8, D154008_ALDRICH, 3,5-dimethyl-2-cyclohexenone, SCHEMBL1042381, CTK3J5660, NSC-845, NSC10113, 3,5-dimethyl-cyclohex-2-en-1-one, EINECS 214-369-2, NSC-10113, AKOS015917649, MCULE-4391727742, AN-48619, KB-70228, OR037108, OR126990, AI3-21772, RT-002626, FT-0658302, S01-0583