Process for the preparation of aromatic nitriles

Details Process for the preparation of aromatic nitriles Process for the preparation of aromatic nitriles

2002-07-08

2004-08-31

McKane, Joseph K. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Nitriles

C544S242000, C546S286000, C548S236000

Reexamination Certificate

active

06784308

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a process for the preparation of aromatic nitriles by reaction of halogenoaromatics or aryl perfluorosulfonates with alkali metal cyanides in the presence of palladium catalysts, polyethers, and zinc.
The palladium-catalyzed substitution of halogens in aromatic compounds by alkali metal cyanides is disclosed, for example, in U.S. Pat. No. 4,211,721 or T. Okano et al., Synleft, 1998, page 243. The processes described there, however, have the disadvantage that both the yields and the low turnover numbers of the catalysts (TON) of at most 170 make industrial realization uneconomical. An improved process was presented by Maligres et al. in Tetrahedron Letters, 40, 1999, page 8193. However, the cyanide source used is expensive zinc cyanide, which is not acceptable for the industrial scale. The need therefore existed to develop a process that makes possible the palladium catalyzed cyanation of halogenoaromatics or aryl perfluorosulfonates using cheap alkali metal cyanides with high turnover numbers and yields.
SUMMARY OF THE INVENTION
There has now been found a process for the preparation of aromatic nitrites of the general formula (I)
Ar—[CN]
n
  (I)
in which
Ar represents a substituted or unsubstituted aromatic radical, and
n represents one or two,
comprising reacting
(a) an aromatic compound of the general formula (II)
Ar—[X]
n
  (II)
 in which
Ar and n have the above-mentioned meaning for formula (I), and
X each independently of one another represents chlorine, bromine, iodine, or a perfluoroalkylsulfonyloxy radical,
with
(b) one or more alkali metal cyanides, in the presence of
(c) a palladium catalyst,
(d) zinc, and
(e) one or more polyethers, and
(f) optionally, an aprotic solvent.


REFERENCES:
patent: 4211721 (1980-07-01), Cotter
patent: 6331628 (2001-12-01), Kondo et al.
patent: 2001039938 (2001-02-01), None
Synlett “Catalytic Cyanation of Aryl Halides with NaCN in the Presence of Crowned Phosphine Complexes of Palladium under Solid-liquid Two-phase Conditions” by Tamon Okano, Asahiro Iwahara, and Jitsuo Kiji (month unavailable) 1998 pp. 243-244.
Tetrahedron Letters 40 (month unavailable) 1999 pp. 8193-8195 “A highly catalytic robust palladium catalyzed cyanation of aryl bromides” by Peter E. Maligres, Marjorie S. Waters, Fred Fleitz and David Askin.

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