Poly substitution products

An important side reaction is the formation of diaryl methane derivatives ArCHaAr. Moreover poly substituted products may be obtained as minor products. Aromatic compounds have been treated with formaldehyde and hydrogen bromide or hydrogen iodide instead of hydrogen chloride. The formaldehyde may be replaced by another aldehyde the term Blanc reaction however stands for the chloromethylation only. 

The direct bromination of aliphatic ketones occurs readily, often giving isomeric mixtures. Thus, methyl ethyl ketone and an equimolar quantity of bromine yield the a-btomomethyl (17%) and the a-bromoethyl (50%) isomers polybrominated products are also formed. On the other hand, only the tertiary hydrogen in methyl isopropyl ketone is substituted upon monobromination. By varying the conditions for the bromination of acetone, mono- or poly-substitution products may be formed e.g., bromo-acetone (44%), a,a -dibromoacetone (60%), and a,a,a -tribromoacetone (60%). ... 

It seems better to take up the first line of development and to study next those hydrocarbons which differ from the members of the saturated series but which are capable of forming the same typical substitution products and derivatives. We shall then be in a position to consider, irrespective of the character of the hydrocarbon root, the various complicated mixed compounds or poly-substitution products which are known and which are of importance. 

The next group of poly-substitution products are those containing two or more cyanogen radicalsy (—CN). These correspond exactly to the poly-halogen compounds, from which they may be prepared by the action of potassium cyanide. 

Oxidation Products of Poly-hydroxy Alcohols.—In our study of the mixed poly-substitution products we considered the mixed alcohol-aldehyde and alcohol-ketone compounds and showed that they are intermediate oxidation products between poly-hydroxy alcohols and poly-basic acids (p. 228). To illustrate, when glycerol, tri-hydroxy propane, is oxidized the following products are obtained. 

In this formula all of the hydrogen atoms are represented as similarly placed in reference to each other. Before enlarging upon this formula and showing its complete form let us see if it agrees with the facts in regard to isomerism. Its agreement with the fact that only one mono-substitution product is known has just been considered. How is it in regard to the poly-substitution products The facts are these ... 

Isomerism.— As all of the second group, in which substitution occurs in the side chain, considered as benzene derivatives, are mono-substituted benzenes, they do not exist in isomeric forms, and only one compound of each formula is known. The first group, however, in which halogen substitution occurs in the ring, are all poly-substitution products of benzene, since toluene itself is a mono-substituted benzene. Mono-chlor toluene is, therefore, a di-substituted benzene, and occurs in the three forms, as follows ... 

Mono- and Poly-phenols.—As with the other ring substitution products of benzene and its homologues we have not only mono- but also di- tri- and other poly-substitution products, so also we have polyphenols in which more than one hydrogen atom of the ring is substituted by the hydroxyl group. In these poly phenols the conditions of position isomerism are present so that ortho, meta and para vicinal, symmetrical and unsymmetrical isomers are known. 

The substituted phenols result from the substitution of an additional element or group in the original benzene ring. Derivatives of only the mono-phenols will be mentioned. Considered as benzene derivatives these compounds will be poly-substitution products and, therefore, possible of existence in isomeric forms. We thus shall have ... 

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