Page:Encyclopædia Britannica, Ninth Edition, v. 5.djvu/574

Rh 562 CHEMISTRY [ORGANIC. (C 02 H ]4 ) are noteworthy as forming a homologous series, the successive terms of which differ by +C 4 H 2. These compounds present certain analogies in their chemical behaviour, and are particularly characterized by their giving rise to quinones when oxidized. In the formation of a quinone H 2 is replaced by 2 f - ( | thus- C 10 H 30 = C 10 H 6 2 &quot; + Nnphthoquinone. OH, Naphthalene. Pyrene (C 16 H 10 ), although not a member of the series, furnishes a quiuone on oxidation. Benzene does not yield a quinone by direct oxidation. The relationship of the second and third members of the series to benzene will be seen from their graphic formulae : H C H A ^ HC C H H C HC C H C C H HC C H HC C C C C H  S c H 1 HC i fl H ii C C !! C H / ^  / / HC c 1 il 1 HC ii C C-H H Benzene H H Naphthalene. C C I I H H Anthracene. The hydrocarbons, being the parent compounds of the remaining organic bodies, have been treated in greater detail than is necessary in the case of the other families. II. ALCOHOLS. Formulation and Classification. It has already been pointed out that alcohols can be considered as derivatives of hydrocarbons by the substitution of hydroxyl for hydrogen, and, consequently, as compounds of hydroxyl with hydro carbon radicles (p. 553). Each series of hydrocarbons can thus be supposed to give rise to a corresponding series of alcohols : CnH 2 n+ 2 C n H 2 +1 .HO (CnH 2n )&quot;(HO) a C n H 2n _ 3 .HO (CH 2W _,)&quot;(HO) 4 (CH 2 - 4 r (HO) 6 CnH^-HO (C B H aB _ B ) (HO) 5 C&quot;H 2 n g CH in _-.HO C n H 2n _ 8 (HO) 2 Alcohols containing 1, 2, n semi-molecules of hydroxyl are said to be monohydric, dihydric, n-hydric. The dihy- dric alcohols of the ethene series are termed ylycols. Alcohols derived from unsaturated hydrocarbons act as unsaturated compounds. Series C rt H 9n+1 . HO. Some of these alcohols (derived from paraffins) have been previously quoted in illustration of homologous series (p. 552). The first member, methyl alcohol (CH 3 HO), is termed carbinol, and the remaining terms can be derived from this by the replacement of H by C n H 2n+1 radicles. Thus, CH 3 HO Methyl alcohol or Carbinol. C(CH 3 )H 2 HO Ethyl alcohol or Methyl carbinol. C(C 2 H 5 )H 2 HO. Propyl alcohol or Ethyl carbinol. Since the paraffins can be formulated as derivatives of methane (see p. 556), and the present series of alcohols as derivatives of paraffins, it follows that these alcohols can be likewise regarded as methane derivatives : H HO It will be convenient to distinguish the carbon atom in combination with hydroxyl as the &quot; typical carbon atom.&quot; The higher members of the series are susceptible of several kinds of isomerism, which may now be con sidered. Passing over the first two members, which are not capable of being formulated in more than one way, the third member (propyl alcohol) may be written as C.C 2 H 5 .H 2 .HO Ethyl carbinol. or C(CH 3 ) 2 H.HO Dimethyl carbinol. Thus, the first kind of isomerism consists in the replace ment of one C n H 2n+1 radicle by two others, each containing a smaller number of carbon atoms. The fourth member of the series (tetryl or butyl alcohol) may be written : C.C,H-.H .HO C(CH 3 )(C 2 H 5 )H.HO Methyl-ethyl carbinol. C(CHo) 3 .HO Trimethyl carbinol. Propyl carbinol. The next kind of isomerism, as exemplified by the third of the above formulae, consists in the substitution of three C n H 2n+1 radicles for the three hydrogen atoms of carbinol. Now, as carbinol contains but three replaceable hydrogen atoms (not regarding the atom contained in the hydroxyl, the replacement of which gives rise to a new class of com pounds), trimethyl carbinol is the type of a series of alcohols, in which the number of C B H 2n+1 radicles com bined with the typical carbon atom is a maximum. The isomeric alcohols of the present series can thus be con veniently classified under the three following groups : 1. Primary alcohols, in which the typical carbon atom is combined with but one other carbon atom 2. Secondary alcohols, in which the typical carbon atom is combined with two other carbon atoms C(C n H 2n+1 ) 2 H.HO. 3. Tertiary alcohols, in which the typical carbon atom is combined with three other carbon atoms C(C n H 2n+1 ) 3 .HO. Another cause of isomerism among alcohols is to be found in the constitution of the C n H 2n+1 radicles (see also p. 550). Thus we may have C.C 3 H r .H 2 .HO isomeric with C.CH(CH 3 ) 2 .H 2 .HO Propyl carbinol. Pseudopropyl carbinol. C(CH,)(C 4 H 9 )H.HO C.CH 3 [CH 2 .CH(CH 3 ) 2 ]H.HO Methyl butyl carbinol. Methyl isobutyl carbinol. Each of the three above-named groups is thus capable of a further division into two sub-groups, such as normal