Hydrocarbons Mono-substitution products

Isomerism of Di-chlor Ethanes.—When, however, we study the constitution of the poly-halogen ethanes we find that isomerism occurs just as in the case of the propyl iodides and of the hydrocarbons above propane. In the case of ethane it is a fact that only one mono-substitution product of any type is known, thereby proving the symmetry of the ethane molecule and the like character of all six of the hydrogen atoms. When two hydrogen atoms are substituted by two chlorine atoms two dif event compounds are produced both having the composition C2H4CI2. From the constitution of the ethane molecule, that has been established by its synthesis from methane (p. 16), we can readily see how this may be explained as we may have two hydrogen atoms replaced by two chlorine atoms in two different ways, as follows ... 

Synthesis.—We have shown that the alkyl halides are mono-substitution products of the hydrocarbons, i.e., one hydrogen of the hydrocarbon has been substituted by a halogen, e.g., methyl iodide, CH3—I. Now when methyl iodide is treated with ammonia a new compound is formed having the composition CHsN and the other product of the reaction is hydrogen iodide. 

The simpler mono substitution products of these hydrocarbons a) Halogen substitution products. 

In our discussion we have shown the relation of the different groups to each other and the reactions by which, in some cases, we may pass from one to the other. Of the hydrocarbons which are the mother substances we have considered only the one series, viz., the saturated hydrocarbons or paraffins. Of the substitution products or their derivatives we have studied only the simplest members, viz., the mono-substitution products i.e.j those resulting from the substitution in the hydrocarbon chain of only one element or group. As the substituting elements and groups which we have considered include all of the more common ones we may say that we have studied the principal type compounds of the saturated series. 

The method which has been sketched can be used only when the structures of certain reference-compounds are known. When the aromatic compounds were first studied it was necessary to establish by some absolute method the structure of a few compounds to which others might be referred. A number of ingenious methods were devised to solve this problem. But one of these, that of Korner, will be described here. The method is based on the determination of the number of mono-substitution-products which can be obtained from the compound, the structure of which is to be ascertained. The application of the method to disubstitution-products is well illustrated by the case of the three dimethylbenzenes (xylenes). The three hydrocarbons have the following melting points and boiling points (I) m.p. —28°, b.p. 142° (II) m.p. —54°, b.p. 139° (III) m.p. 15°, b.p. 138°. Xylene (I) yields two mononitro derivatives, xylene (II) yields three, and xylene (III) yields but one such derivative. The facts lead to a definite conclusion as to the structure of the isomers. This will be seen from the following formulas —... 

Blair, C. M., Henze, H. R. (1932). The number of stereoisomeric and non-stereoisomeric mono-substitution products of the paraffins. J. Amer. Chem. Soc. 54, 1098 idem. The number of stereoisomeric and non-stereoisomeric paraffin hydrocarbons. 1538-1545. 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

Nitration. Nitration conducted with nitric acid alone or in combination with sulfuric acid, provides an efficient method for preparation of mono-, di-, and trinitro derivatives of many aromatic hydrocarbons and of hydroxy, halo, and other substitution products. The polynitro compounds accessible by the direct route have the m-orientation, and o- and p- dinitro compounds, though obtainable by indirect methods, are rare. Products of nitration are useful dye intermediates. 

Isomerism.—Isomerism in the case of the acids is of the same character as that of the alkyl halides and the alcohols if we consider the acids as mono-carboxyl substitution products of the hydrocarbons. In the five carbon acids, the pentanoic or valeric acids, we have one compound which possesses an asymmetric carbon atom. It is the 2-methyl butanoic-i acid. According to the van t Hofif-LeBel theory this compound should exist in three forms, dextro lew and inactive. By oxidation of the fermentation amyl alcohol which is a mixture of 2-methyl butanol-1 and 2-methyl butanol-4 there is obtained a mixture of two of the valeric acids, viz., the 2-methyl butanoic-i acid and the 2-methyl butanoic-4. This same mixture is found naturally in the roots of Valeriana officinalis. By separating out the 2-methyl butanoic-4 acid the 2-methyl butanoic-1 acid is obtained. This acid is inactive, but has nevery with certaintyy been separated into its optical components, though it is claimed that a dextro form has been obtained. 

This reaction is entirely different from that of phosphorus penta-chloride on alcohol, in which the hydroxyl of the alcohol is replaced by one chlorine, and the mono-halogen substitution product of the hydrocarbon results (p. 81). If our ideas in regard to the constitution of aldehyde are correct, this reaction must mean, that, in the di-chlor ethane formed in this way, the two chlorine atoms are linked to the same carbon atom. Such a structure represents a compound which is plainly unsymmetricaL... 

The most common oxygen substitution products of the hydrocarbons to be considered are the alcohols, aldehydes, ketones, acids, and esters. The solubility behavior of these derivatives may be predicted by applying Rulfis I and II. Solubility data for the mono-hydroxy alcohols in water is shown in Table XII. 

Hydrocarbons reacting with cesium lluoroxysulfate in acetonitrile at 35 C yield mono- and disubstituted products. Norbornane gives 2-e.Yo-fluoronorbornane (20). while adamantane (21) is converted into the 1-fluoro. 2-fluoro, and 1,3-difluoro products with substitution on the tertiary carbon strongly predominating.20... 

Figure 11.5 shows that the functional group compositional analysis of the pyrolysis oil/waxes derived from the fixed-bed pyrolysis of PVC, PS and PET is very different from the polyalkene plastic pyrolysis oil/waxes. The spectra of the PVC pyrolysis oil/wax shows that the characteristic peaks of alkanes and alkenes are present as described for the polyalkene plastics. Since the PVC plastic polymer is based on a similar backbone structure to the polyalkene plastics, a similar degradation product oil/wax composition may be expected. However, the spectra for PVC in Figure 11.5 show that there are additional peaks in the region of 675-900 cm and 1575-1625 cm The presence of these peaks indicates the presence of mono-aromatic, polycyclic aromatic and substituted aromatic groups. Benzene has been identified as a major constituent in oils derived from the pyrolysis of PVC whilst other aromatic compounds identified included alkylated benzenes and naphthalene and other polycyclic aromatic hydrocarbons [19, 32, 39]... 

The unsaturated dibasic acids bear the same relation to the saturated dibasic acids, just considered, as the unsaturated mono-basic acids, acrylic acid, crotonic acid, etc. (p. 172), do to the saturated monobasic acids, acetic acid, etc. They are also the oxidation products of the unsaturated hydrocarbons, alcohols, and aldehydes just as oxalic and succinic acids are of the corresponding saturated compounds. As the simplest dibasic acid containing an ethylene unsaturated group will contain two carboxyl groups and also two doubly linked carbon atoms there must be at least four carbons in the compound. This compound will therefore correspond to succinic acid of the saturated series. Now succinic acid may be derived from either butane by oxidation or from ethane by substitution. Similarly the corresponding unsaturated acid may be derived from butene by oxidation or from ethene by substitution. All of these general relationships may be represented as follows ... 

The reaction of dialkylaluminum hydrides with mono- or di-substituted acetylenes provides the best route to alkenyldialkylaluminums . The hydroalumination of acetylene itself gives polymers Monohydroalumination of terminal acetylenes can be conducted either neat or in hydrocarbon solvents (< 50°C). The products are (E)-alkenylalanes as the result of a regio and stereoselective cis addition of Al—H to the C=C bond i- ... 

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