||||||||||||||| USOOS258534A United States Patent (19) 11 Patent Number: 5,258,534 Larson et al. (45) Date of Patent: Nov. 2, 1993 (54) PREPARATION OF TRIALKYLSILYL Chemistry of Cyanotrimethylsilane'', Advances in Sili NTRILE con Chemistry (Ed. G. L. Larson), vol. 1 (1991). W. C. Groutas, D. Felker, "Synthetic Application of 75 Inventors: Gerald L. Larson, Newtown; Thomas Cyanotrimethylsilane, Iodotrimethylsilane, Azido V. John, Yardley; Ram R. Chawla, trimethylsilane, and Methylthiotrimethylsilane', Syn Bensalem, all of Pa.; Chitoor S. thesis, Nov., 861 (1980). Subramaniam, Kendall Park, N.J. F. Duboudin, P. Cazeau, F. Moulinas, O. Laporte, "A 73) Assignee: Huls America, Inc., Piscataway, N.J. New One-Pot Synthesis of Sillylated Cyanohydrins', Synthesis, Mar., 212 (1982). (21) Appl. No.: 14,231 J. K. Rasmussen, S. M. Heilmann, "A Simple, Safe and (22) Filed: Feb. 5, 1993 Inexpensive Preparation of Trimethylsilyl Cyanide', 51) Int. Cl................................................. C07F 7/10 Synthesis, Jul., 523 (1979). 52 U.S. C. ................................ 556/415; 252/183.13 B. Uznanski, "An Improved Preparation of Trimethyl 58 Field of Search .................... 556/415; 252/183.13 silyl Cyanide', Synthesis, Oct., 154 (1978). Primary Examiner-Paul F. Shaver 56 References Cited Attorney, Agent, or Firm-Davis Hoxie Faithfull & U.S. PATENT DOCUMENTS Hapgood 3,032,575 5/1962 Freitag et al. ...................... 556/415 57 ABSTRACT 4,328,351 5/1982 Findeisen et al. ... 556/415 4,429,145 l/1984 Reetz et al. ... ... 556/415 Trialkylsilyl nitrile is prepared by anhydrously reacting 4,570,009 2/1986 Findeisen et al. ................... 556/415 stoichiometric amounts of trialkylsilyl halide, hexaalk yldisilazane or trialkylsilyl amine, and hydrogen cya OTHER PUBLICATIONS nide, in the absence or presence of a solvent or inert gas J. V. Seppala, M. Harkonen, "Effect of the Structure of atmosphere. No catalyst is necessary, and the reaction External Alkoxysilane Donors on the Polymerization of preferably is performed at a temperature of from 5 C. Propene with High Activity Ziegler-Natta Catalysts', to 25 C. Makromol. Chem, 190, 2535-2550 (1989). J. K. Rasmussen, S. M. Heilmann, L. R. Krepski, "The 21 Claims, No Drawings . 5,258,534 1 2 PREPARATION OF TRIALKYLSILYL NITRILE V.O. Reikhsfeld, Zh. Obshch. Khin.., Vol. 55, 1537 (1985). Also, yields of 90-100% have been observed for BACKGROUND OF THE INVENTION the synthesis of n-butyldimethylsilyl nitrile, t-butyl dimethylsilyl nitrile, and phenyldimethylsilyl nitrile The invention relates to the preparation of trialkylsi 5 using fluoride ion catalysis. Rasmussen et al. at 71. lyl nitrile (also known as trialkylsilyl cyanide and cyanotrialkylsilane). Trialkylsilyl nitriles, especially These reactions involve the following equilibrium: trimethylsilyl nitrile, are used to form silylated cyano hydrins from ketones or aldehydes, to conjugatively fH, (catalyst. fH, add cyanide to enones, to form acylnitriles from acyl 10 chlorides, to protect ketones, to add to imines to form (CH3)3SiCN +R-Si-Cl r-i-CN + (CH3)3SiC) a-amino nitriles, and to add to oximes to give a-cyano H, T Ge. CH3 oximes. Trialkylsilyl nitrile will lead to cycloadducts upon reaction with carbodiimides, dimines, isocyanates The high yields were generally obtained by distilling and isothiocyanates and nitriles. Further, trialkylsilyl 15 the trimethylchlorosilane as it was formed. Rasmussen nitrile adds to acetylenes, allenes and nitrones and opens et al. at 71. It should be noted that for each mole of oxiranes and oxetanes. It also serves as a source of cya trialkylsilyl nitrile formed, a mole of trimethylsilyl chlo nide ion in various nucleophilic substitutions, both or ride is formed as a by-product. ganic and inorganic. Trimethylsilyl nitrile has been Quantitative yields of trimethylsilyl nitrile have been described as one of the most versatile silicon reagents 20 observed from an equimolar mixture of chlorotrime for the purposes of organic synthesis. J.K. Rasmussen, thylsilane and potassium cyanide. F. Duboudin, P. Ca S.M. Heilmann, L.R. Krepski, "The Chemistry of zeau, F. Moulines, O. Laporte, "A New, One-Pot Syn Cyanotrimethylsilane,” in Advances in Silicon Chemistry thesis of Sillylated Cyanohydrins,” Synthesis, Mar, 212 (Ed., G.L. Larson), Vol. 1, 66 (1991). (1982). A 71% yield has also been observed for the same Trialkylsilyl nitrile has been prepared for several 25 reaction, although the authors noted that scrupulous years by reaction of the iodosilane (R)3SiI with silver drying of the glassware and solvent were not per cyanide according to the reaction formed. J.K. Rasmussen, S.M. Heilmann, "A Simple, Safe and Inexpensive preparation of Trimethylsilyl Cy anide,' Synthesis, July, 523 (1979). The process, how i. 30 ever, generates one mole of potassium chloride as a R-i- -- ACN->R-i-CN - AgI by-product per mole of trialkylsilyl nitrile. Further, R3 R3 Rasmussen and Heilmann report using anhydrous N methylpyrrollidone as solvent, which is expensive and Trimethylsilyl nitrile has also been obtained from the difficult to recycle. corresponding sulfide, bromide and chloride. W.C. 35 The use of hydrogen cyanide is described in B. Uz Groutas, D. Felker, "Synthetic Application of Cyano nanski, "An Improved Preparation of Trimethylsilyl trimethylsilane, Iodo trimethylsilane, Azidotrimethylsi Cyanide," Synthesis. Oct., 154 (1978). According to lane, and Methylthio-trimethylsilane,' Synthesis, Nov., Uznanski, trimethylsilyl chloride is reacted with a 25 861 (1980), report obtaining an 80% yield through reac mol % excess of hydrogen cyanide and triethylamine in tion of silver cyanide with chlorotrimethylsilane. De 40 spite the obvious expense of silver cyanide, it was the diethyl ether giving a 70% yield of trimethylsilyl nitrile. reagent of choice for the preparation of trialkylsilyl Uznanski's method produces only moderate yields and nitriles for several years. Rasmussen et al. at 68. generates an equimolar amount of triethylamine hydro Trialkylsilyl nitrile has also been obtained in moder chloride as a by-product. ate yields through reaction of chlorotrimethylsilane 45 The current state of the art involving cyanide salts is with potassium mercuricyanide in DMF, reaction of described in U.S. Pat. No. 4,429,145, to M.T. Reetz. hexamethyldisilazane with hydrogen cyanide, reaction The Reetz method employs potassium cyanide. The of methoxytriethysilane with pivaloylcyanide in the Reetz method uses anhydrous N-methylpyrrolidone as presence of aluminum chloride, and from cyanide ex solvent and 10 mol % potassium iodide as a catalyst. change between chlorotriphenysilane and cyanotrie 50 Both chemicals are expensive and difficult to recycle. thylsilane. Rasmussen et al. at 68-69. The reaction of hexamethyldisilazane with hydrogen cyanide was pub SUMMARY OF THE INVENTION lished by DuPont workers in 1958 in J. Amer.Chem.- Trialkylsilyl nitrile is prepared by anhydrously react Soc., 80, 4151-4153 (1958). The DuPont workers dis ing stoichiometric amounts of trialkylsilyl halide, hex close a yield of 36.7% trimethylsilyl nitrile and 45% 55 aalkyldisilazane or trialkylsilyl amine, and hydrogen ammonium cyanide. The ammonium cyanide is a nitrile cyanide, in the absence or presence of a solvent or inert salt and is as such very difficult to handle. gas atmosphere. Trimethylsilyl nitrile has been prepared by reacting a DETAILED DESCRIPTION OF THE diethyl ether solution of trimethylchlorosilane and hy INVENTION drogen cyanide with a lithium dispersion in petroleum. 60 A modification of this is the subject of U.S. Pat. No. Under the process of the invention, trialkylsilyl nitrile 3,032,575. This has been taken further by first forming is prepared through two alternative reactions (I and II) lithium cyanide from LiH and hydrogen cyanide, and which can be represented by the following equations: then preparing trialkylsilyl nitrile from the lithium cya (I) RR2R3Si-X-RR2R3Si-N- nide. 65 H-SiRR2R3-3HCN area as a A moderate yield of 72% trimethylsilyl nitrile has -3R1,R2R3SiCN--NHX been obtained through reaction of bis(trimethylsilyl)sul R1R2R3Si-X-R1R2R3Si-NH2--2HCN - - - - fide with dicyanodimethylsilane. M.D. Mizhiritskii, -2R1R2R3SiCN--NHX 5,258,534 3 4. The reagents, following either equation I or II, are slight positive pressure of the inert gas is sufficient to preferably reacted in stoichiometric amounts. Thus, maintain an inert atmosphere. according to equation I, the preferred molar ratios are It is advantageous initially to charge the dried reac as follows: trialkylsilyl halide to hydrogen cyanide is tion vessel with trialkylsilyl halide and either hexaalkyl 1:3; hexaalkydisilazane to hydrogen cyanide is 1:3; and 5 disilazane (eq. I) or trialkylsilylamine (eq. II) and to stir trialkylsilyl halide to hexaalkyldisilazane is 1:1. Accord the mixture. It is also advantageous to feed the hydro ing to equation II, the preferred molar ratios are as gen cyanide into the mixture at a temperature of 5' C. follows: trialkylsilyl halide to hydrogen cyanide is 1:2; While the hydrogen cyanide is being added, it is pre trialkylsilyl halide to trialkylsilyl amine is 1:1; and ferred to allow the reaction mixture to gradually warm trialkylsilyl amine to hydrogen cyanide is 1:2. Stoichio- 10 up to 15' C. After addition of the hydrogen cyanide is metric amounts of reactants are preferred to minimize finished, complete conversion to trialkylsilyl nitrile can difficulties related to product purification and safety. A be completed at 20' C. in approximately