Patent GB-346676-A (GB)
Title: Improvements in the dehalogenation of organic halogen compounds
IPC: C07C17/23
Filed: 1929-09-24
Abstract: Cyclic organic halogen compounds are dehalogenated partially or wholly by treating with reducing agents, other than metals or metal compounds, such as hydrazine and its derivatives, hydroquinone, dioxindol, hydrazobenzene, glyoxal, guanidine, formamide, and formic acid, in the presence of metals whose oxides are easily reduced, or compounds thereof, such as the oxides, carbonates, acetates, halides and complex compounds, and in inert solvents or suspending agents, particularly basic agents such as pyridine, quinoline, collidine, dialkylaniline, and benzyl cyanide.  The dehalogenation is furthered by the action of sunlight or artificial ultraviolet light.  According to examples: (1) 4 : Bz3 : Bz5-trichloroanthraquinone-2 : 1-(N) benzacridone, dichloromonobromoanthraquinone-2 : 1-(N)-benzacridone tetrabromopyranthrone tetrabromo-dichlorobenzanthrone (Example 3 of Specification 325,525, [Class 2 (iii), Dyes &c.]), 1 : 3-dibromo-2-aminoanthraquinone, 1 : 3-dichloro-2-aminoanthraquinone, dibromobenzanthronepyrazolanthrone, 9 : 10-dichloroanthracene-1 : 2 : 3 : 4-tetrachloride, 4 : Bz2 : Bz3 : Bz4 : Bz5-pentachloroanthraquinone-2 : 1 - (N) - benzacridone, Bz2 : Bz3 : Bz4-trichloroanthraquinone-2 : 1-(N)-benzacridone, Bz2 - chloroanthraquinone - 2 : 1 - (N) - benzacridone, 3-bromo-2 : 1-pyridinoanthraquinone, 2 : 4-dinitro-1 : 3 : 6-trichlorobenzene perchloronaphthalene, and hexabromo-8 : 81-dihydroxydinaphthazine (Specification 291,546, [Class 2 (iii), Dyes &c.]), are partially or wholly dehalogenated by treating in solvents, in presence of copper or salts thereof or other metals, with hydrazine hydrate; (2) 4-bromo-Bz3 : Bz5-dichloroanthraquinone- 2 : 1 - (N) - benzacridone is partially dehalogenated with phenylhydrazine in the presence of copper and pyridine ; (3) 4 : Bz3 : Bz5 trichloroanthraquinone-2 : 1 - (N) - benzacridone is treated with formic acid, and with dioxindole, as reducing agents; other compounds also specified for dehalogenation are: polychloro- and polybromodibenzanthrones and isodibenzanthrones, chlorobenzanthrone - pyrazolanthrones, chlorobromo-, chloro-iodo-, and chlorobromoiodo-benzanthronepyrazolanthrones, halogen-3 : 4 : 8 : 9-dibenzo-pyrene-5 : 10-quinones and-4 : 5 : 8 : 9-dibenzo-pyrene-3 : 10-quinones, octobromocyclohexane (gaseous olefinic products being obtained), various polyhalogenated anthraquinone - 2 : 1 - (N) - benzacridones, 4 : Bz5 - chloro - Bz3-nitroanthraquinone - 2 : 1 (N) benzacridone, 4-nitro-, and 4-amino-Bz2 : Bz3 : Bz4-trichloroanthraquinone-2 : 1 -(N)-benzacridone, and other dichloroamino- and dichloromethyl-, dichloro-, trichloro- and tetrachloro-, tribromo- and chlorobromo, anthraquinone-2 : 1 (N)-benzacridones, mononitro-3-bromo-2 : 1-pyridinoanthraquinone, pentabromo-perylene-tetracarboxylic acid dimethyl-diimide, and octochloro-8-81-dihydroxy-di-naptthazine (obtainable by the process of Specification 291,546, [Class 2 (iii), Dyes &c.]). Other metals specified are nickel, iron, cobalt and silver, or their compounds. Specificatio 297,692, [Class 2 (iii), Dyes &c.], also is referred to. Halogenanthraquinone-2 : 1 (N)-benzacridones are obtained by condensing a halogenated or unsubstituted 1-chloro-anthraquinone-2-carboxylic acid with a halogen substituted or unsubstituted aniline or anilide, ring closing, and further halogenation if necessary, or by condensing a 1-halogenanthraquinone containing further halogen groups in required positions with a halogenated o-amino-carboxylic acid, ring closing and further halogenation if necessary.  4 : Bz5-dichloro-Bz3 - nitroanthraquinone - 2 : 1 (N) benzacridone is obtained by nitration followed by halogenation with sulphuryl chloride of the unsubstituted acridone. 3-bromo, and nitro-3-bromo-2 : 1-pyridinoanthraquinone are obtained by condensing 2-amino-3-bromoanthraquinone with glycerol in concentrated sulphuric acid and nitrating the product. Tetrabromopyranthrone and tetrabromobenzanthrone-pyrazolanthrone are obtained by bromination of the parent materials in chlorsulphonic acid in the presence of sulphur or iodine.