Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Patent
1999-08-05
2000-12-12
Tsang, Cecilia
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
C07C25500
Patent
active
061601578
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a preparation process for 4-cyano-4'-hydroxybiphenyl. This compound is known as an intermediate and used, for example, in the synthesis of monomers of liquid crystal polymers (GB 2002767) (J. Polym. Sci., Part C: Polymer Letters, Vol. 28, 345-355 (1990); J. Mater, Chem., 1993, 3(6), 633-642) or for the formation of specific polysiloxanes (U.S. Pat. No. 5,262,052).
4-cyano-4'-hydroxy-biphenyl can be prepared as described in the Application EP 44759 or in J. Mater. Chem., 1933, 3(6), 633-642, by reacting 4-bromo-4'-hydroxy-biphenyl with copper cyanide. Another preparation method described in the application U.S. Pat. No. 5,262,052, consists of reacting di(4-methoxyphenyl)zinc with 4-bromobenzonitrile in the presence of Ni(PPh.sub.3).sub.4. The disadvantage of these processes is that they use toxic agents such as copper cyanide. A subject of the invention is a preparation process which does not use a toxic agent such as copper cyanide or which uses less toxic agents than those described in the state of the art.
The invention thus relates to a preparation process for 4-cyano-4'-hydroxybiphenyl, the process comprising:
The hydroxy group can be protected by the standard methods which are well known to a person skilled in the art. The hydroxy group of 4-phenyl-phenol can be protected, for example, by alkylation. The alkyl group can be a linear or branched alkyl group having up to 5 carbon atoms, examples are methyl, ethyl, propyl, isopropyl, butyl and t-butyl groups.
All the acylation methods which are well known to a person skilled in the art can be used. For example, a Friedel-Crafts acylation can be used.
The reactions in which the ketone is converted into an acid, the acid into an amide and the amide into a cyano group by dehydration, can be implemented by using standard methods known to a person skilled in the art. As regards the amidification, the preferred method consists of converting the acid function into a halide which is then treated with ammonia or an amine.
The deprotection method used depends on the reagent used for the deprotection reaction.
The following examples are presented to illustrate the above procedures and must in no case be considered as a limit to the scope of the invention.
EXAMPLE 1
A solution of 102 g (0.6 mol) of 4-phenylphenol in a mixture of 800 ml of ethanol and 200 ml water is prepared at 40.degree. C., 48 g (1.2 mol) of soda is added, a solution is obtained into which 126 g (1 mol) of dimethyl sulphate is poured over 35 minutes. The reaction medium is taken to reflux for 9 hours. A mixture of 400 ml of water and 400 ml of ethanol is added while warm, and the reaction medium is cooled down to 20.degree. C., separated, washed with water then with ethanol. After drying, 101 g (91% yield) of 4-methoxybiphenyl is obtained in the form of a white powder.
EXAMPLE 2
A solution of 87.5 g (0.656 mol) of aluminium chloride in 365 ml of 1,2-dichloroethane is prepared at 20.degree. C. The solution is cooled down to 0.degree. C. and 33.6 g (0.328 mol) of pure acetic anhydride is added over 15 minutes without exceeding 10.degree. C. An orange-coloured solution is obtained which is left under agitation for 50 minutes and which is then poured over 30 minutes into a solution of 60 g (0.326 mol) of 4-methoxy-biphenyl in 610 ml of 1,2-dichloroethane. A deep red solution is obtained which is taken to reflux for 4 hours. It is cooled down to 0.degree. C. and the reaction medium is poured into 300 ml of 3N hydrochloric acid. After decanting, the aqueous phase is re-extracted with dichloromethane (3.times.100 ml). The combined organic phases are washed with water (3.times.100 ml), and the solvents are eliminated under reduced pressure. The residue is taken up in 450 ml of ethanol, followed by cooling down, drying and washing with ice-cooled ethanol (2.times.100 ml).
After drying, 47.9 g (65% yield) of 4-acetyl-4'-methoxy biphenyl is obtained in the form of a beige powder.
EXAMPLE 3
A solution of 64.7 g (1.61 mol) of soda in 560 ml water is prepared at 0.degree. C. 69.
REFERENCES:
patent: 5262052 (1993-11-01), Rossiter et al.
McMurry, J., "Organic Chemistry" 2nd ed, pp. 533-4, 604, 655, 751, and 767, 1988.
H. Den Heijer et al, "Photoreactions . . . Triplet", Tetrahedron, vol. 33, 1977, pp. 779-786.
Marchalin et al, "Syntheses . . . Dihydropyridines", Collection of Czechoslovak Chemical Communications, vol. 48, No. 11, 1983, pp. 3112-3122 .
Breton Christine Le
Cazaux Jean-Bernard
Murray Joseph
Societe d'Expansion Scientifique Expansia
Tsang Cecilia
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