CH 31 to (1)-methyl2-4-di-isopropyl benzene.
The thermal effects increase as one passes from primary to tertiary alcohols, the values deduced from propyl and isopropyl alcohols and trimethyl carbinol being: - primary =45 08, secondary = 50.39, tertiary = 60.98.
Grignard (Comptes Rendus, 1900 et seq.) showed that aldehydes combine with magnesium alkyl iodides (in absolute ether solution) to form addition products, which are decomposed by water with the formation of secondary alcohols, thus from acetaldehyde and magnesium methyl iodide, isopropyl alcohol is obtained.
On distillation with zinc dust it forms cymene (1.4 methyl isopropyl benzene).
RETENE (methyl isopropyl phenanthrene), CisHis, a hydrocarbon present in the coal-tar fraction, boiling above 360° C.; it also occurs in the tars obtained by the distillation of resinous woods.
In this case it is readily seen that isomerism introduces itself in the three carbon atom derivative: the propyl alcohols, expressed by the formulae CH 3 CH2 CH 2 0HandCH 3 CHOH CH3, are known as propyl and isopropyl alcohol respectively.
It may be artificially prepared by the hydrolysis of isopropylcyanide with alkalies, by the oxidation of isopropyl alcohol with potassium bichromate and sulphuric acid (I.
Reduction by sodium amalgam converts it into isopropyl alcohol; oxidation by chromic acid gives carbon dioxide and acetic acid.
Hexahydrocymene (methyl-i-isopropyl-4-cyclo-hexane), C10H20, is important since it is the parent substance of many terpenes (q.v.).