Patent GB-801233-A (GB)
Title: Improvements in or relating to preparation of aromatic compounds
IPC: C07C45/51
Filed: 1956-04-23
Abstract: A peroxide polymer useful as an intermediate for preparing aromatic compounds, comprises as recurring units a peroxide group bonded to an aromatically unsaturated nucleus through a methylene group, and optionally units of an aromatically unsaturated nucleus bonded through a methylene group.  The two types of units may be as blocks. By aromatically unsaturated nucleus is meant both carbocyclic and heterocyclic nuclei having a resonating type of unsaturation of the benzoid type.  The polymers are made by copolymerizing oxygen and a quinodimethane monomer, i.e. a compound comprising at least one diunsaturated six-membered cyclic group to which is united two methylene groups.  The cyclic group may be substituted by halogen or methyl radicals.  The polymerization is preferably effected below - 45 DEG C. in the presence of an organic solvent saturated with oxygen.  The polymerization may also be effected by spraying a solution of the monomer into a chamber filled with oxygen.  The formation of the polymer is facilitated by the presence of carbonyl compounds especially aldehydes.  Suitable quinodimethane monomers are p-quinodimethane, p-naphthaquinodimethane, 2,5-quinopyrimidinyldimethane, 2-methyl quinodimethane, 2 - fluoro - p - quinodimethane, 2,3-dimethylquinodimethane, and 2,5 - difluoro - p - quinodimethane.  The quinodimethane monomers are prepared by pyrolyzing, e.g. at 950 DEG  to 1300 DEG C., compounds having at least one six-membered aromatically unsaturated cyclic nucleus substituted by methyl groups in the 1 and 4 positions and optionally other substituents such as halogen or methyl groups. After pyrolysis the monomer is quenched in an organic liquid below about - 45 DEG C. The preparation of these monomers is more fully described in Specification 788,662.  The quenching liquid may also function as the polymerization medium.  Liquids mentioned are hexane, petroleum ether, cyclopentene, 1,4-dimethyl cyclohexane, toluene, ethyl benzene, o-ethyl toluene m-diethyl benzene, o-chloroethyl benzene, o-fluoro toluene, 1,1-dichloroethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ether, ethyl n-propyl ether, tetrahydrofurane, carbon bisulphide, methanol, ethanol, isopropyl alcohol, and mixtures.  Typical aldehydes which assist the copolymerization are formal, acetaldehyde, propanal, benzaldehyde, and terephthalaldehyde.  The peroxide polymers may be decomposed at temperatures between 50 DEG  and 150 DEG C. to yield a mixture of aromatically unsaturated compounds substituted in the 1 and 4 positions by groups such as formyl and/or hydroxymethyl groups (see Group IV (b)).  The products of decomposition may be altered by the presence of reducing agents such as ferrous sulphate, sodium hydrosulphite, cuprous sulphate, butyl mercaptan, thiophenol, t-butylamine, dimethylaniline, N-methylaniline or oxidizing agents such as aqueous nitric acid or chromic acid.ALSO:Aromatic or heterocyclic organic compounds substituted in the nucleus by oxygen containing aliphatic groups are made by thermally decomposing a peroxide polymer which contains recurring units of a peroxide group bonded to an aromatically unsaturated carbocyclic or heterocyclic nucleus through a methylene group. The organic compounds may be terephthalaldehyde, p-hydroxymethyl benzaldehyde, p-xylylene glycol, terephthalic acid, 2-methyl-1,4-benzene dialdehyde, 2-fluoro-1,4-benzene dialdehyde, 2,5 - fluoro - 1,4 - benzene dialdehyde, 1,4-naphthalene dialdehyde and mixtures.  The decomposition is preferably effected between 50 DEG  and 150 DEG  C. in the presence of a heat transfer medium such as water, carbon tetrachloride, chloroform, benzene, toluene, p-cymene, acetone, methylisobutyl ketone, methylisobutyrate, or benzyl benzoate.  The nature of the decomposition products can be altered by the presence of reducing agents such as iron filings, ferrous or cuprous sulphate, sodium hyposulphite, mercaptans or amines, and oxidizing agents such as aqueous nitric or chromic acids.  The polymers are prepared by copolymerizing oxygen and a quinodimethane monomer (see Group IV (a)).  The preparation of these monomers is described in Specification 788,662.  Specified monomers are p-quino-dimethane, p-naphthaquinodimethane, 2,5-quinopyrimidinyldimethane, 2 - methylquinodimethane, 2 - fluoro - p - quinodimethane, 2,5-difluoro - p - quinodimethane, and 3 - methyl-2,5 - quinopyridyldimethane.  In Example (1), poly-p-xylene peroxide is decomposed by heating at 90 DEG  C. for 4 hours under reduced pressure, whereby a mixture of p-xylylene glycol, p-hydroxymethyl benzaldehyde and terephthaldehyde was obtained.  In Example (5) polyp-xylene is decomposed in the presence of water and ferrous sulphate or iron filings whereby p-xylylene glycol only is formed. In Example (6) a yield of a major proportion of p-hydroxymethyl benzaldehyde and terephthalaldehyde is obtained by allowing poly-p-xylylene peroxide to decompose slowly at 65 DEG  C. in the presence of water.