The average value for primary alcohols is 44.67 cal., but many large differences from this value obtain in certain cases.
The aldehydes may be prepared by the careful oxidation of primary alcohols with a mixture of potassium dichromate and sulphuric acid,-3Rï¿½CH OH+K Cr 07+4H SO = K2S04+ Cr (SO) +7H O+3Rï¿½CHO; by distilling the calcium salts of the fatty acids with calcium formate; and by hydrolysis of the acetals.
Diamines.-The diamines contain two amino groups and bear the same relation to the glycols that the primary monamines bear to the primary alcohols.
Thus primary alcohols and aldehydes, both of the aliphatic and aromatic series, readily yield on oxidation acids containing the same number of carbon atoms. These reactions may be shown thus: - ï¿½ Rï¿½CH 2 OH -> R.
In this method of preparation it is found that the secondary alcohols decompose more readily that the primary alcohols of the series, and when sulphuric acid is used, two phases are present in the reaction, the first being the building up of an intermediate sulphuric acid ester, which then decomposes into sulphuric acid and hydrocarbon: C2H 5 OH->C 2 H 5 HSO 4 ->C 2 H 4 +-H 2 SO 4.