Hydrocarbons alkyl group

Chemicae Formuea R(X) , where R is a hydrocarbon alkyl group and X is a halogen. One or more halogens may be present in one compound... 

Some Alkanes and the Related Alkyl Groups Parent Hydrocarbon Alkyl group, —R... 

In spite of being ionic many quaternary ammonium salts dissolve m nonpolar media The four alkyl groups attached to nitrogen shield its positive charge and impart lipophilic character to the tetraalkylammonium ion The following two quaternary ammonium salts for example are soluble m solvents of low polarity such as benzene decane and halo genated hydrocarbons... 

Release agents function by either lessening intermolecular interactions between the two surfaces in contact or preventing such close contact. Thus, they can be low surface-tension materials based on aUphatic hydrocarbon, fluorocarbon groups, or particulate soHds. The principal categories of material used are waxes, fatty acid metal soaps, other long-chain alkyl derivatives, polymers, and fluorinated compounds. 

A small fraction of the hydrocarbons decompose and deposit on the catalyst as carbon. Although the effect is minute ia terms of yield losses, this carbon can stiU significantly reduce the activity of the catalyst. The carbon is formed from cracking of alkyl groups on the aromatic ring and of nonaromatics present ia certain ethylbenzene feedstocks. It can be removed by the water gas reaction, which is catalyzed by potassium compounds ia the catalyst. Steam, which is... 

Reactions other than those of the nucleophilic reactivity of alkyl sulfates iavolve reactions with hydrocarbons, thermal degradation, sulfonation, halogenation of the alkyl groups, and reduction of the sulfate groups. Aromatic hydrocarbons, eg, benzene and naphthalene, react with alkyl sulfates when cataly2ed by aluminum chloride to give Fhedel-Crafts-type alkylation product mixtures (59). Isobutane is readily alkylated by a dipropyl sulfate mixture from the reaction of propylene ia propane with sulfuric acid (60). 

Inclusion of additional alkyl groups on the aromatic ring leads to decongestants with longer duration of action. Thus, reaction of the arylacetonitrile, 109, obtainable from hydrocarbon, 107, by chloromethylation (108), followed by displacement of the halogen by means of cyanide ion with ethylenediamine, leads to xylometazoline (111). The analogous reaction of the oxygenated derivative, 110, affords oxymetazoline (112). ... 

Aromatic hydrocarbons substituted by alkyl groups other than methyl are notorious for their tendency to disproportionate in Friedel-Crafts reactions. This tendency has previously limited the application of the isomerization of para- or ortho-) m ky -benzenes to the corresponding meta compounds. At the lower temperature of the present modification, disproportionation can be minimized. 

Alkyl aluminium halides are used in many ways as coinitiators for the cationic polymerization. Due to presence of alkyl groups, which have the characteristics of potential carbanions, the alkyl aluminium halides and the counterions formed from them cause the following irreversible competing reactions whereby hydrocarbons are released — Termination by interaction of the cation with the alkyl group of the counterion, e-g-... 

Replacement of an aromatic hydrogen by an aliphatic group is called alkylation and the attached group is called an alkyl group. Industrially, benzene is alkylated by reaction with an olehnic hydrocarbon such as ethylene to make ethylbenzene, or with propylene to produce isopropylbenzene. The replaced benzene hydrogen becomes part of the attached group. 

There is no ready explanation for the relative instability of the alkyl-substituted cyclopentadienylthallium(I) compounds. The change in the hydrocarbon substrate, which results from introduction of an alkyl group, is likely to be small and insufficient to account for the dramatic stability differences [in the case of 9-R-substituted fluorenes, for example, where R = H, CHj, C2H5, or terf-butyl, the maximum difference in p. units between any two compounds is only 1.6 (9)]. The change in orbital overlap caused by introduction of an alkyl group is also likely to be small the l,T-dialkylferrocenes, for example, are stable compounds 137). At present, the only plausible explanation appears to be that the relative stabilities of the crystal lattices vary markedly 169). 

If X is an alkyl group and Y = H, the reference compound XIII is a straight chain hydrocarbon, and the second process above consists in its transformation to a branched unit (XIV) having a single substituent. Hence... 

If both X and Y are alkyl groups, the reference compound is a singly branched hydrocarbon, and it is converted to a doubly branched structural unit in the hypothetical dehydrogenation process hence... 

The higher thermal stability of dialkylaluminium hydrides over the corresponding trialkylaluminiums is particularly marked in this case with 2 branched alkyl groups [ ] Used industrially as a powerful reducant, it is supplied as a solution in hydrocarbon solvents. The undiluted material ignites in air unless diluted to below 25%... 

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