Patent GB-771329-A (GB)
Title: Improvements in the preparation of di-alkali derivatives of dimerized vinyl aromatichydrocarbons and their conversion into diaryl-substituted hexanedioic acids
IPC: C07C51/15
Filed: 1954-11-25
Abstract: Finely dispersed sodium or potassium is reacted with a vinyl aromatic hydrocarbon in a medium comprising an aliphatic monoether containing a methyl group and an oxygen to carbon ratio of not less than 1 : 4 or a polyether derived from a polyhydric alcohol having all the hydroxyl hydrogen atoms replaced by alkyl groups or mixtures thereof, preferably in the presence of a small proportion of a polycyclic aromatic hydrocarbon and if desired in the presence of a solid friable attrition agent at a temperature below about 0 DEG  C. to form the dialkali metal derivative of the dimerized vinyl aromatic hydrocarbon.  Specified vinyl aromatic hydrocarbons include styrene, o-, m- and p-methyl styrenes, c1-C4 alkyl styrenes, and aryl styrenes.  Pure sodium may be replaced by mixtures containing a major proportion of sodium such as sodium-potassium or sodium-calcium alloys. Specified reaction media include dimethyl ether, methyl ethyl ether, methyl n-propyl ether, methyl isopropyl ether, the dimethyl, methyl ethyl, diethyl, methyl butyl, ethyl butyl, dibutyl and lauryl butyl ethylene glycol ethers; trimethylene glycol dimethyl ether, glycerol trimethyl ether and glycerol dimethyl ethyl ether.  Inert reaction media such as are used in forming the alkali-metal dispersion may be introduced into the ether medium.  Suitable polycyclic aromatic hydrocarbons include naphthalene, phenanthrene, diphenyl, the terphenyls, dinaphthyl and tetraphenyl ethylene, and mixtures thereof.  The friable attrition agent may be an inorganic salt such as sodium chloride, sodium sulphate or potassium sulphate, sand, diatomaceous earth, zircon, rutile or graphite.  It may be preground or added in a relatively coarse state to the alkali metal dispersion in a ball mill.  The sodium or potassium may be dispersed in an inert hydrocarbon such as n-octane, iso-octane, n-heptane or a straight run kerosene, or dibutyl ether.  The di-alkali metal derivatives may be carbonated without isolation from the reaction mixture by pouring the mixture on to dry solid carbon dioxide or by passing dry carbon dioxide gas into it to give salts of dicarboxylic acids containing two more carbon atoms than the dimerized hydrocarbon.  The salts may be converted to the free acids by acidification and separation by filtration, extraction or other procedure.  In an example a dispersion of metallic sodium in di-n-butyl ether is added to ethylene glycol diethyl ether containing a minor proportion of o-terphenyl, the mixture being maintained under nitrogen, and cooled to - 60 DEG  C.  Styrene is added to give the di-sodium derivative of dimerized styrene.  The reaction mixture is poured on to excess of solid carbon dioxide and then quenched with water.  The water layer is acidified with concentrated hydrochloric acid to give a mixture of diphenyl adipic acids. Example (4) describes the preparation of a ,a 1-ditolyl adipic acids. Preparation of 1,4-diphenyl butane.-The mixture containing the disodium derivative is reacted with excess water, and the organic solvent layer separated.  Solvent is stripped off, the residue dissolved in toluene and polystyrene precipitated by addition of ethanol.  The supernatant liquid is distilled under reduced pressure to give a fraction consisting of 1,4-diphenyl butane.