Patent GB-734128-A (GB)
IPC: C07C2/72
Abstract: 734,128. Alkylation of carbocyclic hydrocarbons. ETHYL CORPORATION. Nov. 6, 1952 [March 29, 1952], No. 27967/52. Class 2 (3). [Also in Group VI]- A carbocyclic hydrocarbon containing a saturated tertiary carbon atom adjacent to an unsaturated nuclear carbon atom and having attached thereto one hydrogen atom is alkylated by reacting with a non-conjugated olefin at elevated temperature in the presence of an alkali metal as catalyst. The alkylation yields products in which the hydrogen on the tertiary carbon atom is replaced by an organic radical derived from the alkylating olefin and containing the same number of carbon atoms as the olefin. The carbocyclic hydrocarbon may be aromatic or it may be an alicyclic or hydroaromatic hydrocarbon containing ring unsaturation and having alpha to a ring unsaturation a tertiary saturated carbon atom either nuclear or extranuclear attached to only one hydrogen atom. The catalyst may comprise any alkali metal or mixture of alkali metals, thus lithium, sodium, potassium, rubidium and caesium may be used. The alkali metal is preferably used in the form of a dispersion but molten alkali metal or massive solid alkali metal can also be used. The catalyst may also be mixed with a relatively inert material such as calcium, a preferred form of such mixtures being the socalled " sludge " obtained in the production of sodium by electrolysis of a sodium chloridecalcium chloride mixture. The reaction should preferably be carried out in substantially oxygen-free surroundings and the reactants should be low, e.g. below 0.5 per cent, in oxygen content. Specified reaction temperatures are from about 150‹ to 500‹ C. and the reaction pressures may be from 2 to 3000 atmospheres. Higher pressures favour a higher degree of alkylation, e.g. dialkylation of p.-diisopropyl benzene with ethylene to form p-di-(tert.-amyl)- benzene, whilst lower pressures favour lower degrees of alkylation, e.g. monoalkylation in the latter reaction to form p-isopropyl (tert.- amyl)-benzene. Mixtures of olefines and/or of the carbocyclic hydrocarbons may be used and either or both of the reactants may be dissolved in an inert solvent, e.g. a paraffin, cycloparaffin or an aromatic solvent containing no hydrogen-bearing carbon atoms alpha to an aromatic nucleus. As one of the latter type of aromatic solvents one of the reaction products, e.g. di-(tert.-amyl)-benzene may be employed. The process may be carried out batchwise or in a continuous manner. In the latter case the reactants in liquid or vapour state or in mixed liquid-vapour state may be passed over a fixed bed of catalyst which may be admixed with an inert carrier or the liquid or liquid-vapour reaction can be carried out in the presence of a suspended catalyst which is transported through the reaction zone by the velocity of liquid reactants and products. The reactants may be diluted with inert gases such as propane, ethane, methane, nitrogen, helium and neon. Carbocyclic hydrocarbons in which the carbon atom alkylated is cyclic include 3,6-dimethylcyclohexene, 1,4 - di - ethyl - 1,2,3,4 - tetrahydronaphthalene, 1,3 - dimethylhydrindene, and 3,5-dimethylcyclopentene and examples of compounds which undergo alkylation of acyclic carbon atoms are cumene, diisopropylbenzene, sec.-butylbenzene, 2-phenylpentane, 3-phenylpentane, isopropylnaphthalenes, isopropyl anthracenes, sec.-butyl phenanthrenes, 1,1-diphenylethane, 2-phenyldodecane and isopropyltert.-butylbenzenes. Compounds which undergo either cyclic or acyclic alkylation, or both, include 1,4-dimethyl-1,2,3,4-tetrahydro-5-isopropylnaphthalene. The alkylating agent is preferably a non-cyclic mono-olefine, e.g. ethylene, propylene, butene-1, butene-2, pentene-1, pentene-2, hexene-1, hexene-2, hexene- 3, a heptene, octene, nonene, decene, undecene, or dodecene, isobutylene, 3-methylheptene-1, 2-ethyl-pentene-1, or 3-methyl-hexene-3. Other olefins which may be used are cyclic olefins, non-conjugated polyolefines and mono-olefines of more than 12 carbon atoms, e.g. cyclohexene, cyclopentene, 1,4-cyclohexadiene, 1,4- or 1,5- hexadiene, tetradecenes, and pentadecenes, e.g. pentadecene-1. The products obtained by alkylating various carbocyclic hydrocarbons with various olefines are specified. Examples describe the alkylation of isopropylbenzene with ethylene to form tert.-amylbenzene using potassium and sodium respectively in the form of a fine dispersion as catalyst. It is stated that the products of the invention are useful in the formation of synthetic detergents, as solvents, as constituents of blended fuels and as constituents of insecticidal compositions.