1911 Encyclopædia Britannica/Methyl Alcohol

METHYL ALCOHOL (CH₃OH), the simplest aliphatic alcohol; an impure form is known in commerce as wood-spirit, being produced in the destructive distillation of wood. The name methyl, from Gr. μέθυ, wine, ὕλη wood, explains its origin. Discovered by Boyle in 1661, it was first carefully studied by Dumas and Péligot in 1831; its synthesis from its elements (through methane and methyl chloride) was effected by Berthelot in 1858. It is manufactured by distilling wood in iron retorts at about 500° C., when an aqueous distillate, containing methyl alcohol, acetone, acetic acid and methyl acetic ester, is obtained. This is neutralized with lime and redistilled in order to remove the acetic acid. The distillate is treated with anhydrous calcium chloride, the crystalline compound formed with the alcohol being separated and decomposed by redistilling with water. The aqueous product is then dehydrated with potash or lime. To obtain it perfectly pure the crude alcohol is combined with oxalic, benzoic or acetic acid, and the resulting ester separated, purified, and finally decomposed with potash. Methyl alcohol is also obtained in the dry distillation of molasses. The amount of methyl alcohol present in wood spirit is determined by converting it into methyl iodide by acting with phosphorus iodide; and the acetone by converting it into iodoform by boiling with an alkaline solution of iodine in potassium iodide; ethyl alcohol is detected by giving acetylene on heating with concentrated sulphuric acid, methyl alcohol, under the same circumstances, giving methyl ether.

Pure methyl alcohol is a colourless mobile liquid, boiling at 66°–67°, and having a specific gravity of 0·8142 at 0° C. It has a burning taste, and generally a spirituous odour, but when absolutely pure it is said to be odourless. It mixes in all proportions with water, alcohol and ether. Its compound with calcium chloride has the formula CaCl₂·4CH₃·OH, and with barium oxide BaO·2CH₃OH. Oxidation gives formaldehyde, formic acid and carbonic acid; chlorine and bromine react, but less readily than with ethyl alcohol. The chief industrial applications are for making denatured alcohol (q.v.), and as a solvent, e.g. in varnish manufacture; it is also used for a fuel; a purer product is extensively used in the colour and fine chemical industries.

Methyl chloride CH₃Cl, is a gas, boiling at −23°, obtained by chlorinating methane, or better, from methyl alcohol; wood spirit is treated with salt and sulphuric acid, or hydrochloric acid gas conducted into the boiling spirit in the presence of zinc chloride, the evolved gas being washed with potash and dried by sulphuric acid. It is also prepared by heating trimethylamine hydrochloride. Alcohol dissolves 35 volumes and water 4. Methyl bromide is a liquid, specific gravity 1·73, boiling point 13°; methyl iodide has a specific gravity of 2·19, and boils at 43°.