Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/575

Rh ALCOHOLS.] CHEMISTRY 563 primary and iso-primary, normal secondary and iso- secondary, &amp;lt;fec., &amp;lt;kc. In the higher members a further number of isomeric modifications become possible. Many of these isomeric alcohols are known, but a large number have yet to be discovered to complete the series. The following is a list of the normal primary alcohols : Names. Formulae. BoiJ ing-points. Methyl alcohol CH 3 HO 66 C Ethyl C 2 H 5 .HO 78 4 Propyl ,, C 3 H 7 .HO 97-6 Butyl C 4 H 9 .HO 116 Amyl CUT,,. HO 137 Hexyl ,, 157 Heptyl C 7 H 15 .HO 176 5 Octyl C 8 H r. HO 196 5 -VT 1 isonyl ,, 200 i Cetyl 50 ) Ceryl C-j-H-g HO 70 f Melting- Melissyl, , 88 ( P nt - These alcohols (up to nonyl alcohol) are limpid liquids, the viscidity of which increases with the molecular weight. The three other members are white crystalline solids. Methyl, ethyl, and propyl alcohols are readily miscible with water, the remaining members are more or less of the nature of oils. Most of these alcohols possess peculiar and characteristic odours. The boiling-points of the isomers are generally lower than those of the corresponding normal alcohols. The normal and iso-primary alcohols can be obtained from the corresponding haloid paraffin derivatives by the action of potassium hydroxide : Normalprimary..C n H 2n+1 #a + KHO = C B H 2B+1 .HO + KHa. Iso-primary ............. (CH 3 ) 9 CH(CH 9 ) B .#a + KHO = (CH 3 ) 2 CH(CH 2 );. HO + Kffa. Likewise by the action of nascent hydrogen on the corre sponding normal primary and iso-primary aldehydes : (C n H 2u+1 )COH + H 2 = C n H 2n+1 .CH 2. HO. The synthesis of alcohols from the corresponding defines has already been alluded to (p. 559). Since ethine can be formed directly from its elements (p. 559), and ethene from ethine (p. 559), it is obvious that ethyl alcohol can by these means be formed synthetically. Secondary alcohols are produced by the action of nascent hydrogen on ketones: CO(C n H 2n+1 ) 2 + H 2 = C(C n H 2n+1 ) 2 H.HO. Tertiary alcohols are prepared by the action of organo- zinc compounds on the chlorides of acid radicles, C n H 2n+1 .COCl, and treatment of the product with water. The metamerism of the three groups of alcohols is strikingly displayed by their behaviour on oxidation. Thus, primary or iso-primary alcohols are oxidized first to aldehydes H^COH + OH 2 ; Aldehyde. then to acids containing the same number of carbon atoms (C n H 2n+1 )CH 2 .HO + = Alcohol. (C n H 2B+1 )COH + = C n H 2n+1 .COOH. Aldehyde. Acid. Secondary alcohols are oxidized first to ketones C(C n H 2n+1 ),H.HO Alcoliol. = CO(C n H 2n+1 ) 2 Ketone. then to one or more acids containing a smaller number of carbon atoms than the alcohol CO(C n H. 2n+1 ) 2 Ketone. = C n H 2n+1 .COOH + C B H OB O 2 2n+1 Acid. Tertiary alcohols are probably first oxidized to ketones, and ultimately to a mixture of two or more acids contain ing a smaller number of carbon atoms than the alcohol. By particular reactions an alcohol of one group can be converted into an isomer of another group, such, for instance, as normal primary butyl alcohol into the iso- primary alcohol, and the latter into the tertiary alcohol. In many of their reactions alcohols are the analogues of water ; for instance HHO + K = KHO + H Water. Potassium. Potassium hydroxide. C 2 H 5 .HO + K = C. 2 H 5 .KO + H. Ethyl Potassium alcohol. ethylate. In other reactions they resemble metallic hydroxides : KHO + HC1 = KC1 + OH 2 Potassium Potassium hydroxide. chloride. C 2 H..HO + HC1 = C 2 H 5 .C) + OH, Ethyl alcohol. Ethyl chloride. Of this series the best known members are methyl and ethyl alcohols. The former (or &quot; wood-spirit &quot;) is chiefly obtained from the crude &quot; wood vinegar &quot; produced by the destructive distillation of wood. Ethyl alcohol is common &quot; spirits of wine,&quot; and is always procured by the fermenta tion of sugar, which, in contact with yeast, undergoes the following change C 6 H 12 O 6 = 2CO 2 + 2C 2 H 5 .HO . Many of the higher members are formed by the fermenta tion of grain, sugar-beet molasses, potato, &c. Fusel oil consists chiefly of isomeric modifications of amyl alcohol. Names. Formulae. Boilisg-points. CJI^.HO. Vinyl alcohol C 2 H 3 HO Allyl C,H . HO 96 C C n H 2 n 3. HO . Propargyl alcohol C 3 H 3 . HO 110 115 Borneol and camphol C 10 H 17 .HO 212 Series C n H 2n _K.HO, Phenols. The alcohols of this series bear the same relation to the benzene hydrocarbons that the ethyl series of alcohols bear to the paraffins. Thus these alcohols at once divide themselves into two ineta- meric series according as the hydroxyl replaces hydrogen in the benzene or paraffin radicle ; for instance, methyl- benzene or toluene (C 6 H 5 .CH 3 ) gives rise to C 6 H 4 (HO).CH 3 Cresol. and C 6 H 5 .CH 2 (HO). Benzvl alcohol. The alcohols of the benzylic seriesf C G H 5 _ are true alcohols in their chemical behaviour, being formed from the haloid derivatives of their corresponding hydrocar bons by the action of potassium hydroxide, and being oxidized to acids containing the same number of carbon atoms. The alcohols represented by cresol, C 6 H 5 _,HO.(C B H 2n+1 ) lll , or phenols, on the other hand, act more like saturated compounds, and in some respects resemble acids. They cannot be directly obtained from their corresponding haloid hydrocarbon derivatives, and are converted by oxidation into quinones. The phenols yield substitution-derivatives oy the action of halogens, nitric acid, &c. ; such, for ex ample, as C 6 H 4 C1.HO, C 6 C1 5 .HO ; Monochloro- Pentachloro- phenol. phenol. G H 4 (N0 2 ).HO, C 6 H 3 (N0 2 ) 2 .HO , C 6 H 2 (N0 2 ) 3 .HO. Mononitrophenol. DinitrophenoL ^toicS* The phenols yield sulphonic acids when acted on by strong sulphuric acid, C 6 H 4 (HO)(HS0 3 ), C 6 H 3 (HO)(HS0 3 ) 2 ,