H —OH K.— OH Cat — OH Water Potassium Methyl hydroxide alcohol Again, as metallic hydroxides combine with acids to form salts, so alcohols combine with acids to form esters (ethereal salts), which are perfectly analogous to the salts of inorganic chemistry. The following two equations repre sent, respectively, the formation of a salt and of an ester: KOH + HCl = KCI Potassium Hydrochloric Potassium Water hydroxide acid chloride ej-LOI-I O, -I- FLO Ethyl Acetic Ethyl-acetic Water alcohol acid ester The hydrogen of the hydroxyl group of an alcohol can be replaced either by metals or by hydrocarbon radicles. In the former case, a metallic alcoholate is obtained; in the latter, an ether. Thus, by the action of metallic sodium on ordinary (ethyl) alcohol, sodium alcoholate is obtained, according to the following chemical equation: Na = + II Ethyl alcohol Sodium alcoholate On the other hand, by dehydrating ethyl alcohol, ordinary ether is obtained, as follows: -I- 0,11,0H — H,0 = 2 molecules of ethyl alcohol Ethyl ether In this transformation (usually effected by the dehydrating action of sulphuric acid) , the ethyl group of one molecule of alcohol evidently takes the place of the hydroxyl hydrogen of another molecule. An analogous reaction takes place when a mixture of two different alcohols is sub jected to the dehydrating action of sulphuric acid: + CfIOH — ILO CH, Ethyl Methyl Methyl-ethyl alcohol alcohol ether The chemical similarity between the alcohol ates and the ethers is further shown by the fact that the latter may be readily obtained from the former. Thus, methyl ether may be obtained
by the action of methyl iodide on sodium-methyl ate (an alcoholate), according to the following chemical equation: 011,0Na + CH,I = Aral Sodium Methyl Methyl methylate iodide ether iodide The chemical transformations characterizing the three sub-classes of the alcohols, viz., the pri mary, secondary, and tertiary alcohols, may now be briefly considered.
I. It was mentioned above that primary alco hols contain the group CILOH. When they are oxidized, this group is changed into the group /II C which is characteristic of the aldehydes— another important. class of organic compounds. Thus, when ethyl alcohol is oxidized with chromic acid, ordinary aldehyde is obtained, according to the following chemical equation: + 0 = 011,0110 + Ethyl alcohol Aldehyde By further combination with oxygen, aldehydes readily yield acids, the group CHO being ex changed for the acid group C—OTT. Thus, when ordinary aldehyde is oxidized, acetic acid is produced, as follows: