Synthesis of dimethylheptenol.
Note by Ph. Barbier, presented by Friedel.
Originally published as “Synthèse du diméthylhepténol.” Comptes Rendus, v. 128, p. 110.
In an earlier Communication (Comptes rendus, v. CXXVI, p. 1423), I reported the formation of 2,6-dimethyl-2-hepten-6-ol by the action of alcoholic potash on lemonol [ I ], in support of my conclusions about six very consistent analyses of the alcohol, of its acetic ester, and of the oxide of dimethylheptene that I derived from the alcohol by extended reaction with sulfuric acid. The purpose of this note is to report the procedure that I followed to realize the synthesis of dimethylheptenol.
In this experiment, I used the general method conceived by Saytzeff, but with an important modification that allowed me to apply it to a special case with which I was concerned; that modification consists of substituting magnesium for zinc.
The reaction is executed as follows: into a flask fitted with a powerful cooler were placed 100 grams of natural methylheptenone [ II ], 150 grams of anhydrous ether and 20 grams of magnesium turnings; then 113 grams of methyl iodide was added dropwise. After about one third of the methyl iodide was added, the liquid turned yellow and soon a rapid reaction began; the flask was cooled under a water flow and the reaction was continued with the slow addition of the rest of the methyl iodide.
The mixture was left to react for twelve hours, and the magnesium compound was decomposed with dilute sulfuric acid over ice. After washing with a dilute solution of sodium acetate and with distilled water, the liquid was separated and submitted to vacuum fractional distillation; on the third pass, 35 grams of pure dimethylheptenol was isolated, as the following results of the analysis show:
The formulas represent the reaction which has taken place:
Synthetic dimethylheptenol is a colorless liquid that boils between 79-80° under 10 mmHg. Its odor, density, and boiling point agree with those of the alcohol derived from lemonol. Its reacts precisely in the same manner as this compound with oxidizers and with dilute sulfuric acid; finally, the two alcohols can be identified by their acetic esters; synthetic dimethylheptenyl acetate boils at 84-86° under 10 mmHg, the same as the acetate synthesized from the alcohol derivative of lemonol. Upon analysis, the following values are obtained:
This synthesis therefore definitively confirms my previous results. I will add in closing that the substitution of magnesium for zinc in the Saytzeff reaction is novel and that it has allowed me to achieve a certain number of syntheses to which I wish to return at some point.
Translator's Notes
Originally published as “Synthèse du diméthylhepténol.” Comptes Rendus, v. 128, p. 110.
In an earlier Communication (Comptes rendus, v. CXXVI, p. 1423), I reported the formation of 2,6-dimethyl-2-hepten-6-ol by the action of alcoholic potash on lemonol [ I ], in support of my conclusions about six very consistent analyses of the alcohol, of its acetic ester, and of the oxide of dimethylheptene that I derived from the alcohol by extended reaction with sulfuric acid. The purpose of this note is to report the procedure that I followed to realize the synthesis of dimethylheptenol.
In this experiment, I used the general method conceived by Saytzeff, but with an important modification that allowed me to apply it to a special case with which I was concerned; that modification consists of substituting magnesium for zinc.
The reaction is executed as follows: into a flask fitted with a powerful cooler were placed 100 grams of natural methylheptenone [ II ], 150 grams of anhydrous ether and 20 grams of magnesium turnings; then 113 grams of methyl iodide was added dropwise. After about one third of the methyl iodide was added, the liquid turned yellow and soon a rapid reaction began; the flask was cooled under a water flow and the reaction was continued with the slow addition of the rest of the methyl iodide.
The mixture was left to react for twelve hours, and the magnesium compound was decomposed with dilute sulfuric acid over ice. After washing with a dilute solution of sodium acetate and with distilled water, the liquid was separated and submitted to vacuum fractional distillation; on the third pass, 35 grams of pure dimethylheptenol was isolated, as the following results of the analysis show:
Found: C=76.05 H=11.04
Theory: C=76.06 H=10.96
Theory: C=76.06 H=10.96
The formulas represent the reaction which has taken place:
Synthetic dimethylheptenol is a colorless liquid that boils between 79-80° under 10 mmHg. Its odor, density, and boiling point agree with those of the alcohol derived from lemonol. Its reacts precisely in the same manner as this compound with oxidizers and with dilute sulfuric acid; finally, the two alcohols can be identified by their acetic esters; synthetic dimethylheptenyl acetate boils at 84-86° under 10 mmHg, the same as the acetate synthesized from the alcohol derivative of lemonol. Upon analysis, the following values are obtained:
Found: C=71.92 H=11.04
Theory: C=71.74 H=10.87
Theory: C=71.74 H=10.87
This synthesis therefore definitively confirms my previous results. I will add in closing that the substitution of magnesium for zinc in the Saytzeff reaction is novel and that it has allowed me to achieve a certain number of syntheses to which I wish to return at some point.
Translator's Notes