USOO7030260B2

(12) United States Patent (10) Patent No.: US 7,030,260 B2 Asirvatham et al. (45) Date of Patent: Apr. 18, 2006

(54) PREPARATION OF MIXED- Uhlig, W., Synthesis of Functional Substituted Oligosilanes HALO-SILANES Based on Sillyltriflate Derivatives, Organosilicon Chemistry: From Molecules to Materials, Eds. N. Auner, J. Weiss (75) Inventors: Edward Asirvatham, Chatham, NJ Federal Republic of Germany, (1994), pp. 21-26. (US); Jeff Czarnecki, Branchburg, NJ Katzenbeisser, U. Si-Si-Coupling Constants of Bromo (US); Matthew H. Luly, Hamburg, NY and Iododislanes and -trisilanes XSi-H and XSi-Hs. (US); Lawrence F. Mullan, (X= Br, I), Organosilicon Chemistry: From Molecules to Williamsville, NY (US); Alagappan Materials, Eds. N. Auner, J. Weiss, Federal Republic of Then appan, Wilmington, DE (US) Germany, (1994), pp. 37-38. (73) Assignee: Honeywell International Inc., Pátzold, U. Synthesis of Heavily Halogenated Vinylsilanes, Morristown, NJ (US) Organosilicon Chemistry IV: From Molecules to Materials, Eds. N. Auner, J. Weiss, Federal Republic of Germany, *) Notice: Subject to anyy disclaimer, the term of this (1996), pp. 226-228. patent is extended or adjusted under 35 Hassler, K., Köll, W., Synthesis and Spectroscopy of U.S.C. 154(b) by 214 days. Phenylated and Halogenated Trisilanes and Disilanes, Organosilicon Chemistry II: From Molecules to Materials, (21) Appl. No.: 10/377,367 Eds. N. Auner, J. Weiss, Federal Republic of Germany, (1996), pp. 81-88. (22) Filed: Feb. 27, 2003 Hassler, K. Schenzel, K., Syntheses, Si NMR Spectra, and (65) Prior Publication Data Vibrational Spectra of Methylated Trisilanes, Organosilicon Chemistry II: From Molecules to Materials, Eds. N. Auner, US 2004/OO19231 A1 Jan. 29, 2004 J. Weiss, Federal Republic of Germany, (1996), 95-100. Pöschl, U. Siegl, H., Hassler, K., Synthesis, Reactivity, and Related U.S. Application Data Spectroscopy of Phenylated Cyclotetrasilanes and (60) Provisional application No. 60/359,884, filed on Feb. Cyclopentasilanes, Organosilicon Chemistry II: From 27, 2002. Molecules to Materials, Eds. N. Auner, J. Weiss, Federal Republic of Germany, (1996) pp. 113-119. (51) Int. Cl. Hassler, K., -Phosphrus, -Arsenic, Antimony, and C07F 7/04 (2006.01) -Bismith Cages. Syntheses and Structures, Organosilicon (52) U.S. Cl...... 556/484 Chemistry II: From Molecules to Materials, Eds. N. Auner, (58) Field of Classification Search ...... 556/484 J. Weiss, Federal Republic of Germany, (1994), pp. 203-208. See application file for complete search history. W. Uhlig, Convenient Approach to Novel Organosilicon Polymers, Organosilicon Chemistry: From Molecules to (56) References Cited Materials, Eds. N. Auner, J. Weiss, Federal Republic of Germany, (1996), pp. 703-708. U.S. PATENT DOCUMENTS (Abstract Only Forwarded) Adamova, Y., Skachkov, A., 2,894,012 A * 7/1959 Rosenberg et al...... 556,480 Reaction of Boron Trichloride with Tetraflurosilane initiated by Two Frequency-tunable Carbon Dioxide Lasers, Khim. FOREIGN PATENT DOCUMENTS Vys. Energ., (1990) 24 (1), pp. 88-91. GB 79.5772 5, 1958 Stanton, C., McKenzie, S., Sardella, D., Levy, R., GB 1238932 7, 1971 JP 61117112 6, 1986 Davidovitis, P., Boron atom reaction with silicon and JP 3028371 2, 1991 germanium tetrahalides, J. Phys. Chem. 92(16) pp. 4658 JP 2001097709 4/2001 4662. OTHER PUBLICATIONS (Continued) Hassler et al., {Schwingungsspektren, Normalkoodinat enanalysen und Synthesen der t-Butylsilane, Journal of Primary Examiner Johann Richter Organometallic Chemistry, 465 (1-2), 127-135, 1994.* Assistant Examiner Chukwuma Nwaonicha Emeleus H.J., Wilkins, C.J., Some New Ethyl and Phenyl (74) Attorney, Agent, or Firm—Deborah M. Chess Silicon Fluorides, J. Chem. Soc., (1944), p. 454. Lawton E.A., Levy A., Incorporation of Adenosine-5' - (57) ABSTRACT into Ribonucleic Acid, J. Amer. Chem. Soc., (1955) 77, p. 6083. Newkirk, A.E., Preparation of the Methylfluorosilanes, J. The preparation of halosilanes having mixed-halogen Sub Amer. Chem. Soc., (1946) 68, pp. 2736-2737. stituents is described comprising providing an aryl-halo Chao, T.H., Moore S.L., Lane J., Preparation of Some Cyclic silane having one more first and one or more aryl Fluorosilanes, J. Organometal. Chem. (1971) 33, pp. 157 groups, and Substituting one or more of said aryl groups of 16O. said aryl-halo-silane with a second halogen having an Buck, H.M., Bloemhoff W., Oosterhoff J.J., The System atomic number greater than that of said first halogen. Lewis Acid-Nitro Compound as a Strong Electron Accep tor, Tetrahedron Letters,(1960) 9, pp. 5-11. 26 Claims, No Drawings US 7,030.260 B2 Page 2

OTHER PUBLICATIONS Database Chemabs Online Chemical Abstracts Service, Columbus, OH, US; Kuroda Katsuhiko, et al.: “Organic (Abstract Only Forwarded) Adamova, Y., Pankratov, A., -silicon compounds. XI. Preparation and Properties SagitV., Skachkov, A., Stolyarova, G., Shmerling, G., Laser of silicon-functional phenylfluorosilanes and poly Chemical Reaction of Boron Trichloride with Silicon Tet (phenylfluorosiloxane)” XP002265134; Database accession rafluoride, Khim. Vys. Energ., (1978) 12(1), pp. 89-90. No. 76:60125 abstract & Kogyo Kagaku Zasshi, 74 (10), (Abstract Forwarded) Dele-Dubois, M., Wallert, F., 2132-7 Coden: KGKZA7; ISBN: 0368-5462, 1971. Preparation and Laser-Raman Spectroscopic Indentification Patent Abstracts of Japan: vol. 0103, No. 03 (C-378), Oct. of Fluorochlorosilanes, C.R. Acad. Sci., Ser. B, (1971) 16, 1986 & JP 61 117112 A (Central Glass Co., LTD), Jun. 272(18), pp. 1059-1061. 4, 1986 abstract. Airey, W., Sheldrick, G., Preparation and Properties of Database Chemabs Online Chemical Abstracts Service, Columbus, OH, US; Suresh, B. S. et al: "Halogen exchange Methoxytrifluorosilane, and Study of Its Reaction with reactions of silicon tetrafluoride with phosphorus trichloride Boron Trihalides, J. Inorg. Nucl. Chem. (1970) 32(6), pp. and phosphoryl chloride' XP002265135: Database acces 1827-1829. Sion No. 103:204851 abstract & Journal of fluorine Johansen, T., Hagen, K., Hassler, K., Tekautz, G., Stolevik, Chemistry, 29 (4), 463-6 Coden: JFLCAR: ISSN: 0022 R., 1,1,2-Triiododisilane (I2HSi-SiH2I): Molecular 1139, 1985. Structure, Internal Rotation and Vibrational Properties Patent Abstracts of Japan: Vol. 2000, No. 21, Aug. 3, 2001 Determine by Gas-phase Electron Diffraction, Infrared and & JP 2001 097709 A (Tori Chemical Kenkyusho:KK), Apr. Raman Spectroscopy, and Ab Initio Molecular Orbital- and 10, 2001 abstract. Density Function Calculations, J. Mol. Struct., (1999) 509 English translation of Hassler, et al., “Vibration Spectra, (1-3), pp. 237-254. Normal Coordinate Analyses and Syntheses of Tert Kunai, A., Sakurai, T., Toyoda, E., Ishikawa, M., Selective butylsilane tEuSiX3, X=H, D, F, C1, Br, I, Journal of Synthesis of Fluoro-, Fluorohydro-, and Chlorofluorosilanes Organometallic Chemistry, 465 (1994) 127-135. from Hydrosilanes with the Use of a CuCl2(Cu 1)/KF Reagent, Organometallics, (1996) 15, pp. 2478-2482. * cited by examiner US 7,030,260 B2 1. 2 PREPARATION OF MIXED-HALOGEN the bonding characteristics of the halogens involved. In an HALO-SILANES Si Xbond (where X is a halogen), the ability to replace one halogen with another by direct halogen Substitution tends to REFERENCE TO RELATED APPLICATION follow the order of Si X bond strength, Si F>Si– CldSi Bre-Si-I. Thus, fluorine can replace chlorine, bro This application is based on and claims priority to U.S. mine, and iodine, chlorine can replace bromine and iodine, Provisional Application No. 60/359,884 filed Feb. 27, 2002, and bromine can replace iodine. Synthesis of mixed-halogen which is hereby incorporated by reference. halo-silanes by preparative schemes based on direct replace ment of one halogen species with a different halogen species FIELD OF INVENTION 10 are problematic because such reactions tend to lead to complete replacement of one halogen with another. The present invention relates to the preparation of high Although techniques are often employed to shift the reac purity halo-silanes having two or more halogen moieties. tions equilibrium to favor incomplete substitution of one halogen species for another, these reactions nevertheless BACKGROUND 15 produce a distribution of perhalogenated products. Processes that produce a distribution of halosilane species High-purity silanes having two or more different halogen from which a single species must be isolated do not use moieties (referred to herein as “mixed-halogen halo-si starting materials efficiently. In addition, because cognate lanes') are useful sources of atomic silicon and halogens in halosilane species boil over a very narrow range, isolation of a variety of applications. For example, trichloro-fluoro any one species to achieve high purity requires specialized silane (SiFC1), dichloro-difluoro-silane (SiFC1), and equipment, Such as a high theoretical plate distillation col chloro-trifluoro-silane (SiFCI) has been used as a source of high-purity silicon in the preparation of semiconductor umn, which is expensive to obtain and operate. materials and communication-quality fiber optic materials. Therefore, there is a need for a process that uses reactions In addition, it has been recently reported that trifluoro-iodo 25 having high specific conversion of the starting material into silane (SiFI) is particularly amenable to laser isotopic a single product species, thereby efficiently using the starting separation, providing isotopically pure silicon for use in the material. The present invention fulfills this need among preparation of isotopically pure silicon wafers. Likewise, others. fluoro-iodo-silanes have been used as a source of high-purity SUMMARY OF INVENTION iodine in the preparation of iodine gas lasers. Generally 30 speaking, to be of use as an element Source of silicon and halogens, the mixed-halogen halo-silane must be high The present invention provides an efficient approach for purity. The term “high purity” as used herein refers to a preparing a mixed-halogen halo-silane with excellent yield composition comprising at least 99% by weight of one silane and selectivity. Specifically, the approach involves first species and less than 0.5% by weight of non-silane impu 35 preparing a silane functionalized with at least one first rities. halogen and a specific number of aryl groups, and then There are a number of conventional approaches for pre Substituting the aryl groups with a second halogen having a paring high-purity mixed-halogen halo-silanes. One lower bond strength (i.e., higher atomic number) than the approach involves treating elemental silicon with mixtures first halogen. Applicants have found that aryl group Substi of elemental halogens. For example, silicon may be treated 40 tution provides a convenient and predictable mechanism with a mixture of F and C1 to produce SiFC1. Another through which to introduce lower bond strength halogens approach uses tans-halogenation reactions, in which a sili into a silane. Therefore, the approach of the present inven con compound containing one halide species is contacted tion uses this mechanism to add a halogen Substituent of with a metal complex containing a different halide species relatively-low bond strength to a silane after it has been under conditions sufficient to induce halogen exchange 45 functionalized with a relatively-high bond strength halogen. between the various species. For example, FSiCl may be This is a significant departure from prior art approaches produced from the irradiation of a mixture of SiF and BC1. which tend to functionalize the silane with lower bond Other approaches combine these two approaches. For strength halogensfirst and then rely on halogen exchange to example, elemental silicon may be treated with a halide gas, displace a portion of the lower bond strength halogens with e.g., Cl2, and a halo-silane, e.g., SiF, to produce, among 50 higher bond strength halogens to arrive at the desired other species, a mixed-halogen halo-silane, e.g., F-SiCl. mixed-halogen halo-silane. Although these approaches have been used historically to The approach of the present invention offers a number of produce high-purity mixed-halogen halo-silanes, there is a significant advantages over prior art approaches. First, the general desire to reduce the costs associated with their approach does not rely on unpredictable halogen exchange preparation. Naturally, reducing the cost of preparing mixed 55 between a lower bond strength halogen and a higher bond halogen halo-silanes can lead to a reduction in the cost of strength halogen to form a desired mixed-halogen halo producing materials that use them in their preparation. silane. As mentioned above, such an approach typically Furthermore, finding new applications for these mixed results in a distribution of mixed-halogen halo-silane spe halogen halo-silanes depends upon developing economical cies—i.e., silanes having different combinations of halo processes for producing commercial quantities of them. 60 gens. Rather, the approach of the present invention relies on Typically, the most significant barrier to economically pro the predictable substitution of aryl groups by the lower bond ducing high-purity mixed-halogen halo-silanes is separating strength halogens, resulting in a narrow distribution of the desired mixed-halogen halo-silane from the other mixed mixed-halogen halo-silane species. This narrow distribution halogen halo-silane species and byproducts formed during of product eliminates the prior art difficulty of isolating the its preparation. 65 mixed-halogen halo-silane from a wide distribution of other The problems associated with conventional mixed-halo mixed-halogen halo-silanes species, thereby increasing gen halo-silane preparation techniques tend to result from yield and efficiency. US 7,030,260 B2 3 4 Additionally, using an aryl-halo-silane to prepare the final considered often with respect to just a mono-silane com product offers a number of its own advantages. For example, pound, however, it should be understood that the process of since the process of the present invention provides for the the present invention may be practiced with monosilanes predictable substitution of aryl groups by the lower bond and polysilanes. Additionally, although only mixed-halogen strength halogens, the aryl functionality of the aryl-halo halo-silanes are considered in detail herein, the process of silane essentially determines the number of lower bond the present invention may be practiced to prepare halo strength halogens on the end product. This is significant silanes comprising just one halogen moiety. since silanes, which are functionalized in varying degrees 1. Provision of Aryl-halo-silane with aryl groups, are readily isolated using traditional dis The first step in the process of the present invention is the tillation techniques, especially compared to permutations of 10 provision of an aryl-halo-silane. In a preferred embodiment, mixed-halogen halo-silanes which tend to have similar prop the step of providing an aryl-halo-silane comprises provid erties and, thus, are not readily separable. Accordingly, ing a compound of Formula (1): rather than attempting to isolate a particular mixed-halogen (aryl),SiX. halo-silane from its other species, the purification can essen Formula (1) tially be done before its preparation by readily isolating the 15 wherein: particular aryl-halo-silane from which it is prepared. This a=an integer from 1 to 10; way, the isolated aryl-halo-silane will contain the number of aryl groups corresponding to the desired number of lower bond strength halogens on the final product. X is independently selected from F, Cl, and Br, and I; and Furthermore, depending upon the desired halogen com aryl is an aryl or alkylaryl moiety. position of the end product, it may be preferable to effect a Preparation of the aryl-halo-silane is represented sche halogen exchange with an intermediate aryl-halo-silane. For matically in Equation (1) for a monosilane. example, if the intermediate aryl-halo-silane is an aryl X4Si+n(aryl)-Ms (aryl),SiX4+nMX Equation (1) chloro-silane but the desired high-bond strength halogen is fluorine, then a halogen exchange between the chlorine and 25 where (aryl)-M is an organometallic reagent. fluorine can be performed to provide an aryl-fluoro-silane. The reaction of Equation (1) is art-recognized displace Halogen exchange can be a predictable, high yield reaction, ment of a halogen moiety from a silicon atom with the especially if a lower bond strength halogen is exchanged for Subsequent formation of an organo-silane by an organo a higher bond strength halogen. Thus, by using an aryl-halo metallic reagent in which the organic moiety has strong silane, the present invention allows for a highly reliable and 30 Lewis base character. An example of this is the formation of efficient reaction to select the high-bond strength halogen of an organo-silane by treatment of a silicon halide with a the mixed-halogen halo-silane end product. Grignard reagent. It will be appreciated that other organo Other advantages of the present invention may be obvious metal reagents, for example, lithium reagents, can also be to one skilled in the art in light of this disclosure. employed in a reaction of this type. It will be appreciated Accordingly, one aspect of the claimed invention is a 35 that the reaction is applicable to mono- and polysilanes. process for preparing a mixed-halogen halo-silane from an It will be appreciated that even though the reaction will aryl-halo-silane by Substituting the aryl groups with the produce a distribution of possible substitution patterns, it is lower bond strength halogens. In a preferred embodiment, known in the art to adjust the reaction variables to favor aryl the process comprises (a) providing an aryl-halo-silane group replacement of one, two, or three halogen moieties of comprising one or more first halogens and one or more aryl 40 the halo-silane starting materials, as the need for the various groups; and (b) Substituting one or more of the aryl groups intermediate materials dictates. of said aryl-halo-silane with a second halogen having an It should also be noted that by utilizing a starting material atomic number greater than that of said first halogen. Pref that is perhalogenated with all of one species of halogen erably, providing said aryl-halo-silane comprises providing Substituent, the starting material can be economically pro an intermediate aryl-halo-silane having one more third halo 45 vided in a highly pure state. For example, highly purified gens and then exchanging at least a portion of said one or tetrachlorosilane () is an article of com more third halogens of said intermediate aryl-halo-silane CCC. with one or more first halogens of a lower atomic number The aryl moiety of the organometallic reagent can be any than that of said third halogen to form said aryl-halo-silane. aromatic moiety, for example, phenyl, alkyl-substituted phe Furthermore, in the preferred embodiment, providing said 50 nyl, biphenyl, aromatic heterocycles (e.g., pyrrolyl), and aryl-halo-silane further comprises isolating the aryl-halo moieties based on fused aromatic ring compounds (e.g., silane based on the number of aryl groups before substitut napthyl). Preferably, it is chosen based on three consider ing the aryl groups. ations: 1) ease of separation of the aryl-halo-silane product from the reaction mixture of Equation (1) (step 1, above) and DETAILED DESCRIPTION OF PREFERRED 55 of the aryl by-product from the mixed-halogen halo-silane EMBODIMENTS produced in step 2, above; 2) the ability of the organo-silane bond to withstand Subsequent processing conditions (e.g., as The present invention relates to a process for producing described below, the halogen substitution step in which a halo-silanes that contain two different species of halogen purified aryl-halo-silane has some or all of the halogen moieties (mixed-halogen halo-silanes) in high purity and in 60 Substituents replaced by another halogen of lower atomic high yield. The process comprises: (1) providing an aryl number); and 3) reactivity effects on the formation of the halo-silane having one or more first halogens and one or aryl-halo-silane afforded by the choice of the aryl group and more aryl groups, and (2) Substituting at least Some of the its influence on the conversion of the aryl-halo-silane to a aryl groups with a second halogen which has an atomic mixed-halogen halo-silane. Each of these considerations is number greater than that of the first halogen Substituents. 65 considered in more detail below. Each of these two basic steps is considered in more detail With regard to the first consideration, as the aryl moiety below. For purposes of simplicity, the process will be becomes larger, the various silane adducts tend to boil over US 7,030,260 B2 5 6 a wider temperature range and at a higher temperature. In appreciated that anhydrous gas can be addition, the aryl moiety of the aryl-halo-silane intermediate used to fluorinate the aryl-halo-silane, yielding aryl-fluoro is liberated during aryl Substitution (step 2) as the hydrogen silane. The reaction conditions necessary to provide Such adduct. For example, a phenyl moiety is liberated as ben halogen exchange are known to those of skill in the art. Zene. Depending upon the nature of the mixed-halogen 5 The products of the reaction of Equation (1), (aryl) SiX halo-silane produced in the reaction, byproducts of a lower a for n=1-4, boil over a broad range, and can therefore be or higher boiling point may be required. With regard to the isolated in a high-purity form by ordinary fractional distil third point, reactivity advantages which can be realized by lation methods. In contrast, it is worthwhile to note that a careful selection of the aryl substituent are exemplified by mixture ofY,SiX where Y is a second halogen in place selection of a large aryl moiety which, after the first halogen 10 of the aryl group, boil over a narrow range and, unlike a substitution, will tend to block the approach of a subsequent mixture of the cognate aryl species, cannot be separated in organo-metal reagent to the mono-Substituted halo-silane, high purity by ordinary fractional distillation. Thus, the thus Suppressing the formation of multiply or completely mixture of aryl-halo-silanes produced by the first reaction aryl Substituted silanes. Reactivity advantages may be real provides a precursor which is easily isolated in high purity, ized by selection of the substituents on the aryl moiety, for 15 and can be used in the high specificity aryl Substitution example, fluorine or alkyl substituents which will affect the reaction (described below) to produce a high-purity mixed electron density on the silane atom to which it is a Substitu halogen perhalogenated silane product. ent, and thereby alter the reactivity of the silicon atom 2. Substitution of Aryl Groups with Halogen toward halogen exchange or Substitution. The mixed-halogen halo-silane is prepared Substituting at It should be noted that in the formation of the aryl-halo least some of the aryl groups with a second halogen which silane intermediate according to Equation (1), the halo has an atomic number greater than that of the first halogen silane starting material can be chosen to yield a species Substituents. In a preferred embodiment, the aryl groups of which incorporates the halogen having the lowest atomic the silane of Formula (1) are substituted with second halo number of the halogens appearing in the product. Thus, for gens to form the mixed-halogen halo-silane of Formula (2): example, if X,SiCla) is the desired product, and X-Si is 25 iodine or bromine, the first reaction can utilize SiCl, as the (aryl), SiX,Y, Formula (2) starting material, and isolate the species having a number of where: aryl substituents equal to the desired value of “n” in the ls Zsn. product silane during workup of the reaction product mix ture for conversion to product. In Such a case, a Subsequent 30 Preferably, each occurrence of X in the compound is the step, described below, in which the halogen substituents of same and each occurrence ofY in the compound is the same. the aryl-halo-silane intermediate are replaced by a halogen Additionally, if a b-2 and X is F, then it is preferred that substituent of the lowest atomic number that will appear in both fluorine moieties are bonded to the same silicon atom. the product compound will not be necessary, since it is It is also preferred that Zn, that is that all of the aryl groups already present in the compound at this stage of the process. 35 are substituted for halogens in the second step of the process. When fluorine substituents on the silane are desired, The aryl substitution reaction is presented in Equation (3) especially for the case in which the product is monofluoro for the case in which a perhalogenated monosilane product substituted, the high-bond strength of the Si-F bond miti is formed: gates against use of tetrafluorosilane as a starting material (aryl),SiX4+nHY+LA>YSIX4+nH-aryl Equation (3) 40 from a standpoint of efficient utilization of the starting where material and obtaining a narrow product distribution. To aryl is an aryl or alkylaryl moiety, overcome this problem, the process of the present invention X and Y are independently selected from F, Cl, and Br. can include a step in which a chlorosilane is employed to and I such that the atomic number of X is less than Y: provide an intermediate aryl-halo-silane that has chlorine and substituents bonded to the silicone atom(s) of the interme 45 diate where it is desired to have a fluorine atom. These LA is a Lewis acid. chlorine atoms are then exchanged for fluorine atoms, as The reaction of Equation (3) converts the isolated and described below. purified intermediate aryl-halo-silane, whether directly from Thus, it may be preferable to modify the aryl-halo-silane the reaction of Equation (1) or after having had the halogen 50 groups substituted by the reaction of Equation (2) described Such that it comprises the desired halogens. For example, it above, to a halogenated silane containing halogen moieties may be preferable to convert an aryl-Z-silane to an aryl-X- comprising two different halogen species. In the conversion, silane as described in Equation (2): the aryl moieties are substituted by halogen moieties. The (aryl). SiZ,+nHX.H2O>{aryl). Six, Equation (2) reaction comprising the method of conversion can be carried 55 out using gas-phase reagents bubbled through the liquid where: starting material, or it can be carried out in anhydrous Z is a halogen other than X. conditions in a solvent, for example, pentane. Preferably, X has an atomic number lower than Z. For It will be appreciated that this reaction will be equally example, it may be preferable to convert an aryl-chloro effective when applied to any aryl-silane species containing silane to an aryl-fluoro-silane. The reaction can be carried 60 moieties of one halogen species in the formation of halo out by treating the intermediate aryl-halo-silane compound genated silanes containing more than one species of halo from Equation (1), under aqueous conditions, with the gen, whether the product silane is perhalogenated or not, and hydrogen halide acid having the halide moiety desired in the equally applicable to mono- and polysilane species. product. In general, conditions described in Tetrahedron Lewis acids catalyze the reaction comprising the method Letters, 1960, 5, page 11, can be employed to realize this 65 of converting aryl-silane moieties to halo-silane moieties of transformation. Typically, a 40% acid solution is employed the present invention. Any Lewis acid which is capable of at low temperature for several hours. Additionally, it will be coordinating the hydrogen halide used in the reaction, and US 7,030,260 B2 7 8 thereby promote dissociation of the hydrogen from the There follows three examples in which the phenyl-trif halide, can be used to catalyze the reaction. The Lewis acid luoro-silane prepared above was used as a starting material can be generated in situ, for example, generation of (CH3) in the preparation of iodo-trifluoro-silane (Examples 2-4) 3N+H.C1 by contacting HCl and trimethyl amine, where and one example in which it was used as a starting material the Lewis acid is the ammonium ion. Preferred Lewis acids in the preparation of chloro-trifluoro-silane (Example 5). are of the formula MY, where Y is selected from Cl, Br, and I, and M is a metal that can coordinate at least Z+1 halogen The conversion of the phenyl-trifluoro-silane was carried out moieties and has Lewis acid properties when coordinated according to the method of the present invention for the with Zhalogen moieties. That is, Z is the number of halogen Substitution by halogen moieties of aryl moieties in silanes. moeities coordinated in the neutral metal complex. In the 10 In Examples 2, 3 and 5, the reaction is conducted with neat present invention, the most preferred Lewis acids are alu reactants (no solvent), in Example 4, the reaction is con minum trihalides. ducted in the presence of pentane as a solvent. The reactions When the starting silane is a gas, the reaction can be run of Examples 2–4 were conducted without heating the reac by contacting the two vapor phase reactants over the Lewis tion mixture (ambient temperature), this is to say at a acid (which is typically a solid). When the starting silane is 15 temperature of about 25°C. (room temperature). The reac a liquid, the hydrogen halide can be bubbled through the tion of Example 5 was carried out at sub-ambient tempera liquid, with the reactants contacting the Lewis acid present ture. as a Solid phase or dissolved in the liquid phase. Critical to the method of converting aryl-silicon bonds to Examples 2 through 4 halo-silicon bonds of the present invention is that the conditions in which the reactants are contacted are anhy Preparation of Iodo-Trifluoro-Silane drous.

EXAMPLES In all three examples, the reaction was conducted using 25 the same procedure. Anhydrous HI was produced in a gas generating apparatus comprising a flask equipped with a The process of the present invention is illustrated below at two critical stages by the first example, conversion of a pressure equalized dropping funnel and a gas outlet by commercially available phenyl-chloro-silane to the corre placing phosphorous pentoxide into the vessel and treating sponding phenyl-fluoro-silane, thus illustrating the second it with dropwise addition of a 57.1 wt.% aqueous solution reaction in the process, and by the second to fifth examples, 30 of the acid contained in the dropping funnel. The HI vapors the conversion of the phenyl-fluoro-silane to the correspond thus generated were conducted from the gas generating ing iodo-fluoro-silane, (Examples 2 to 4) and chloro-fluoro apparatus to a reaction vessel consisting of a three neck flask silane (Example 5) thus illustrating the third reaction in the equipped with a thermometer, a gas inlet tube, and a dry ice process, the method of converting aryl-silicon bonds to condenser. The flask contained a stirring device and the halo-silicon bonds. 35 reaction mixture comprising phenyl-trifluoro-silane and alu The phenyl-trichloro-silane starting material from which minum triiodide, the Lewis acid catalyzing the reaction, and, the phenyl-trifluoro-silane was prepared in the first example in Example 4, pentane as a solvent. In the three examples, was obtained commercially as an article of commerce. All HI was bubbled through the reaction mixture during the other reagents used were standard laboratory reagent grade course of the reaction until it ceased being generated by the materials. The phenyl-trifluoro-silane prepared in the first 40 gas generating apparatus. The reaction mixture was stirred example was used in reactions of the second to fifth throughout the reaction period, and the reaction mixture was examples. refluxed, using the dry ice condenser to condense and return The products of the examples were analyzed by gas the volatile components to the reaction vessel. At the end of chromatography/mass spectrometry using a GC/MS 45 the reaction, the reaction mixture was analyzed for yield and equipped with a DB-5 column. purity of iodo-trifluoro-silane without separation of the components from the reaction mixture. Example 1 Example 2 Preparation of Phenyl-trifluoro-silane 50 Room Temperature Conversion of Into a reaction vessel equipped with a stirring device and Phenyl-Trifluoro-Silane a dropping funnel was placed phenyl-trichloro-silane. This was cooled to 0°C. in an ice bath. A super-stoichiometric The HI generating apparatus described above was charged amount of HF relative to the chloride content of the phenyl 55 trichloro-silane in the form of a 40% hydrogen fluoride with 17.5 grams of phosphorous pentoxide in the flask and Solution was placed into the dropping funnel and added 14.0 g of aqueous HI in the dropping funnel. The reaction dropwise to the silane with stirring. Temperature was main vessel described above was charged with 0.4 g of AlI and tained at 0°C. and stirring was continued. At the end of the 8.1 g of the phenyl-trifluoro-silane prepared in Example 1. reaction period, the reaction product was worked up by 60 The vessels were purged with dry nitrogen and HI genera distillation and isolation of the phenyl-trifluoro-silane. tion was begun, as described above. The HI vapors were This example demonstrates that aryl-silicon bonds in an passed through the silane in the reaction vessel, and reflux aryl-halo-silane are sufficiently robust to withstand the con ing commenced. The reaction was continued for 30 minutes ditions required to convert the halogen-silicon bonds from at ambient temperature. At the end of this time, the reaction on species of halogen to another. Further, it demonstrates 65 mixture was isolated and analyzed by GC/MS which indi that by starting with a pure aryl-halo-silane, a different pure cated a yield, based on starting silane converted, of 49% species can be obtained. iodo-trifluoro-silane. US 7,030,260 B2 9 10 Example 3 halogen moiety under a variety of conditions that yield a single product from the starting aryl-halo-silane. Elevated Temperature Conversion of Phenyl-Trifluoro-Silane What is claimed is: 5 1. A process for preparing a mixed halo-silane comprising The HI generating apparatus described above was charged the steps of: with 32.6 grams of phosphorous pentoxide in the flask and (a) providing an intermediate aryl-halo-silane having one 22.5 g of aqueous HI in the dropping funnel. The reaction or more third halogens and one or more aryl groups; vessel described above was charged with 2.6 g of AlI and (b) exchanging at least a portion of said one or more third 10.1 g of the phenyl-trifluoro-silane prepared in Example 1. 10 halogens of said intermediate aryl-halo-silane with one The vessels were purged with dry nitrogen and HI genera or more first halogens to produce an aryl-halo-silane tion was commenced, as described above, and passed having one or more first halogens and one or more aryl through the reaction mixture in the reaction vessel. The group; and reaction mixture was heated on a hot water bath with stirring (c) Substituting one or more of said aryl groups of said to about 30° C. over a period of 15 minutes. The reaction 15 aryl-halo-silane with a second halogen having an mixture was held at this temperature for about 3 hours, atomic number greater than that of said first halogen. during which the reaction mixture refluxed. At the end of 2. The process of claim 1, wherein said third halogen has this time, the reaction mixture was isolated and analyzed by an atomic number greater than said first halogen. GC/MS which indicated a yield, based on starting silane 3. The process of claim 2, wherein said first halogen is converted, of 80% iodo-trifluoro-silane. fluorine, said second halogen is one of chlorine, bromine, or iodine, and said third halogen is chlorine. Example 4 4. The process of claim 3, wherein said aryl group is a phenyl group. Room Temperature 5. The process of claim 4, wherein said aryl-halo-silane is 25 an aryl-fluoro-silane selected from the group consisting of Conversion of Phenyl-Trifluoro-Silane in a Solvent phenyl-trifluoro-silane, diphenyl-difluoro silane, and triph The HI generating apparatus described above was charged enyl-fluorosilane. with 17.1 grams of phosphorous pentoxide in the flask and 6. The process of claim 1, wherein providing said inter 13.5g of aqueous HI in the dropping funnel. The reaction mediate aryl-halo-silane comprises: vessel described above was charged with 0.4 g of AlI and 30 preparing said intermediate aryl-halo-silane by providing 8.1 g of the phenyl-trifluoro-silane prepared in Example 1. a halo-silane having two or more third halogens and and 20.2 grams of n-pentane. The vessels were purged with replacing a portion of said two or more third halogens dry nitrogen and HI was generated, as described above, and with one or more aryl groups to form said intermediate passed through the silane/pentane Solution in the reaction aryl-halo-silane. vessel with stirring. The reaction mixture was left to reflux 35 7. The process of claim 6, wherein said halo-silane is a for one hour at ambient temperature. At the end of this time, perhalogenated halo-silane. the reaction mixture was isolated and analyzed by GC which 8. The process of claim 6, wherein said halo-silane is indicated a yield, based on starting silane converted, of 20% SiZ, where Z is selected from Cl, Br, and I, and wherein iodo-trifluoro-silane. preparing said intermediate aryl-halo-silane comprises 40 reacting an aryl-metal reagent with SiZ. Example 5 9. The process of claim 8, wherein said halo-silane is SiCla. Conversion of Phenyl-Trifluoro-Silane to 10. The process of claim 1, wherein providing said Chloro-Trifluoro-Silane intermediate aryl-halo-silane comprises: 45 Substantially isolating it from a mixture of aryl halo Into a heavy walled stainless steel cylinder of 300 ml silanes based on its number of aryl groups. Volume was placed 18.3 g of AICl under a nitrogen purge. 11. A process for preparing a mixed halo-silane compris In one addition, 55 g of the phenyl-trifluoro-silane prepared ing the steps of above was added to the cylinder. The cylinder was sealed by 50 (a) providing an aryl-halo-silane having one or more first fitting a gauge and valve assembly. The cylinder was then halogens and one or more aryl groups; and pressurized to 200 psig with anhydrous HCl and sealed. The (b) Substituting one or more of said aryl groups of said sealed cylinder was placed in an ice bath and manually aryl-halo-silane with a second halogen having an shaken every 15 minutes for the duration of the reaction atomic number greater than that of said first halogen, period. At the end of 27 hours, the cylinder was fitted with 55 wherein providing said aryl-halo-silane comprises prepar a transfer line, connecting the reaction cylinder with a ing said aryl-halo-silane by providing a halo-silane receiving cylinder. The receiving cylinder and transfer line comprising two or more first halogens and replacing a were purged with nitrogen, sealed, and the receiving cylin portion of said two or more first halogens with one or der placed in an ice bath. The reaction cylinder was then more aryl groups to form said intermediate aryl-halo warmed to 38 degrees C. by placing in a water bath and the 60 silane. valve opened, flash distilling the contents of the reaction 12. The process of claim 11, wherein preparing said cylinder into the receiving cylinder. The contents of the aryl-halo-silane comprises reacting an aryl magnesium receiving cylinder were analyzed and found to be about halide with SiF. 99.2% SiFC1 with a yield of about 98 mole % based on the 13. The process of claim 11, wherein providing said starting silane. 65 aryl-halo-silane comprises: These examples demonstrate that the aryl-halo-silane can Substantially isolating it from a mixture of aryl halo be converted to a halo-silane having two different species of silanes based on its number of aryl groups. US 7,030,260 B2 11 12 14. The process of claim 1, wherein substituting one or wherein more aryl groups comprises contacting said aryl-halo-silane M is a metal having a coordination number greater than with HCl in the presence of a Lewis acid of the formula one, and (CH)NH. “Z” is the number of moieties coordinated in a neutral 15. A process for preparing a mixed halo-silane compris 5 complex of the metal. ing the steps of 22. The process of claim 1, wherein said production of an (a) providing an aryl-halo-silane having one or more first aryl-halo-silane having one or more first halogens and one or halogens and one or more aryl groups; and more aryl groups comprises the Sub-steps: (b) Substituting one or more of said aryl groups of said (i) providing a halo-silane having at least two halogen aryl-halo-silane with a second halogen having an 10 moiety, said halogen moiety being the same and atomic number greater than that of said first halogen, selected from Cl, Br, and I; wherein said aryl-halo-silane has the formula: (ii) forming a first intermediate product mixture compris ing an intermediate aryl-halo-silane by Substituting one (aryl),SiX, or more of said halogen Substituents of said halo-silane and wherein said mixed halo-silane has the formula: 15 with a phenyl group; and (iii) replacing the halogen Substituents of said portion (aryl), SiX,Y, with fluorine substituents, thereby forming a phenyl wherein fluoro-silane; a=an integer from 1 to 10; and wherein step (c) comprises contacting said phenyl fluoro-silane with HX under anhydrous conditions in the presence of a Lewis acid, where X is selected from Cl, Br, and I, to form said mixed-halogen halo-silane. X and Y are independently selected from F, Cl, and Br. 23. The process of claim 22, wherein phenyl-fluoro-silane and I; is phenyl-trifluoro silane and HX is HI, and wherein con the atomic number of X is less than Y; and 25 tacting said phenyl-fluoro-silane with HX comprises con tacting said phenyl-trifluoro silane with said HI in the 16. The process of claim 15, wherein, when a-b=2 and X presence of AlI at a temperature above about 29°C. to form is F, then both fluorine moieties are bonded to the same iodo-trifluoro silane. silicon atom. 24. The process of claim 23, wherein at least 80% of 17. The process of claim 15, wherein X and Y are the 30 phenyl-trifluoro silane is converted to said iodo-trifluoro same for each occurrence. silane. 18. The process of claim 17, wherein a 1. 25. The process of claim 23, wherein 0.9 mole equivalents 19. The process of claim 18, wherein Zn. of benzene based on (phenyl)SiF are produced. 20. The process of claim 15, wherein the aryl groups are 26. The process of claim 22, wherein phenyl-fluoro-silane substituted by treatment with a halo-acid of the formula HY 35 is phenyl-trifluoro silane and HX is HCl, and wherein in the presence of a Lewis acid. contacting said phenyl-fluoro-silane with HX comprises 21. The process of claim 20, wherein said Lewis acid is contacting said phenyl-trifluoro silane with said HCl in the a metal halide of the formula: presence of A1C1 to form chloro-trifluoro silane.

MY k k k k k