Patented Oct. 24, 1950 2527,233

UNITED STATES PATENT OFFICE 2,527,233 METHOD FOR THE PREPARATION OF ORGANOS LCON FLUOR DES Frank J. Sowa, Cranford, N. J. No Drawing. Application January 27, 1947, Seria No. 724,717 Claims. 1. (C. 260-448.2) This invention relates to a method for the preparation of alkyl silicon fluorides, cycloalkyl of alkyl, cycloalkyl, aryl or aralkyl silicon chlo silicon fluorides, aryl silicon fluorides and rides by the reaction of silicon tetrachloride aralkyl silicon fluorides. with an ether Solution of an alkyl, cycloalkyl, The alkyl silicon fluorides are compounds hav aryl or aralkyl magnesium halide. However, ing a variety of properties and uses. Thus, the alkyl, cycloalkyl, aryl and aralkyl silicon fluo mono- and di-alkyl silicon fluorides and the rides are not equivalent materials for all pur lower trialkyl silicon fluorides may be hy poses to the corresponding chlorides. For ex drolyzed and condensed, in accordance with pro ample, in the treatment of a cotton textile, the cedures which are well understood in the art, to foregoing silicon fluorides produce much less prepare materials which are useful as film O tenderizing of the fabric than do the corre formers, lubricants, hydraulic fluids, etc. The sponding silicon chlorides. Furthermore, the higher trialkyl silicon fluorides are either very foregoing silicon fluorides hydrolyze less readily difficult or impossible to hydrolyze under even than the corresponding silicon chlorides, and very drastic conditions, and hence are useful hence the hydrolysis of the former can be more ingredients of stable lubricating compositions s easily controlled, assuming that they can be hy and actuating fluids. Similar observations ap drolyzed. ply with respect to the cycloalkyl silicon fluo Alkyl, cycloalkyl, aryl and aralkyl silicon al rides, (i. e., silicon fluorides having attached to koxy compounds are also suitable for the pro the silicon atoms residues of Saturated alicyclic duction of condensates which are useful film hydrocarbons obtained by the removal of an 20 formers, lubricants, hydraulic fluids, etc. These atom of hydrogen from such hydrocarbons), materials, too, are customarily made by the re aryl silicon fluorides (i. e., silicon fluorides hav action of an alkyl orthosilicate with an ether ing attached to the silicon atoms residues of Solution of an alkyl, cycloalkyl, aryl or aralkyl benzene or alkylated benzenes obtained by the magnesium halide. This method results, how removal of an atom of hydrogen from the ben ever, in the production of a mixture of mono-, Zene nucleus thereof), and aralkyl silicon fluo di- and trialkoxy silicon compounds which may rides (i. e., silicon fluorides having attached to be difficult to separate in a highly pure condi the Silicon atoms residues of alkylated benzenes tion because of their relatively close , boiling obtained by the removal of an atom of hydrogen points. It is not known how to separate the from the alkyl groups thereof). Thus, the sili 30 mixture by chemical means. On the other con fluorides having one or two such residues hand, because of the greater differences of their per silicon atom may be hydrolyzed and con boiling points, the corresponding silicon fluo densed to form polymers which are useful as rides are more easily purified. Furthermore, the film-formers, lubricants, hydraulic fluids, etc., silicon fluorides have lower boiling points than whereas the silicon fluorides having three such 35 the corresponding chlorides or alkoxy com residues per silicon atom resist drastic hy pounds, and hence are more easily distilled and drolysis, thus making them useful ingredients lend themselves more readily to gaseous phase of stable lubricating compositions and actuating applications. fluids. In view, therefore, of the limitations of the A conventional method is known for the 40 known methods for the preparation of alkyl, preparation of the alkyl, cycloalkyl, aryl and cycloalkyl, aryl and aralkyl silicon fluorides, of aralkyl silicon fluorides by the Grignard reac the undesirable properties of the corresponding tion, viz., the reaction of silicon tetrafluoride silicon chlorides in comparison with the prop with an ether solution of an alkyl, cycloalkyl, erties of the silicon fluorides, and of the dif aryl or aralkyl magnesium halide. This method 45 ficulty of purifying many mixtures of the cor is not an entirely satisfactory one, however, be responding silicon alkoxy compounds produced cause of the limited solubility of Silicon tetra by reacting an alkyl orthosilicate and an alkyl, fluoride in ether and other organic solvents. cycloalkyl, aryl or aralkyl magnesium halide, it As a result, it is necessary to add the silicon is the object of this invention to provide a new tetrafluoride to the Grignard reagent, this pro 50 method for the preparation of the alkyl, cyclo cedure giving rise primarily to Organosilicon alkyl, aryl and aralkyl silicon fluorides in good compounds having three or four carbon to sili yield and high purity. con linkages per silicon atom. Such products This object is accomplished in accordance with the method of this invention by contacting hy may not necessarily be the ones desired. An s analogous method is known for the preparation genericdrogen formulafluoride with a compound having the 2,527,288 4. combined with the sulfuric acid, a layer of phenyl trifluorosilane separated. This layer was dis in which R is a saturated acyclic hydrocarbon tilled separately and 30 gms, of phenyl trifluoror radical having from one to twelve carbon atoms, silane was obtained boiling at 95-105 C. and a monocycloalkyl radical having from five to 80 gms. of a mixture of the alcohol and the eight carbon atoms in the ring and having a phenyl trifluorosilane was obtained. total of not more than twelve carbon atoms, an aryl radical having a total of not more than Eacample IV twelve carbon atoms, or an aralkyl radical hav A three-necked, round-bottom flask equipped ing a total of not more than twelve carbon 10 with a reflux condenser and a mechanical stirrer atoms, n is an integer from one to three, and was charged with 187.2 gms. of monoamyl tri R’ is a saturated acyclic hydrocarbon radical ethoxysilane and 100 gms. of potassium polyacid having from one to five carbon atoms. fluoride having an available hydrogen fluoride The following examples illustrate the method content of 48.5% by weight. The contents of the of this invention for the preparation of various 5 reaction flask were heated gently and then re silicon fluorides. fluxed for one-half hour with stirring, after Eacample I which a distillate fraction having a boiling range of 74-80° C. was collected. In view of the fact To a 500 cc. flask which was equipped with a that the reaction products (ethyl alcohol and reflux condenser and a mechanical stirrer was monoamyl trifluorosilane) boiled so closely, it added 117 gms. of monoamyl triethoxysilane and 20 was impossible to separate the silane by distilla 93 gms. of sodium bifluoride. The contents of tion. Hence, the alcohol was separated from the the reaction flask were then heated and refluxed silane by contacting the mixture with an excess for about 15 minutes with constant stirring. A of anhydrous calcium chloride to form the reaction took place, as was evidenced by the calcium chloride-ethyl alcohol complex. The formation of ethyl alcohol. The contents of the silane was then decanted from the calcium reaction flask were subsequently distilled directly chloride-ethyl alcohol complex and was there from the flask, and the fraction boiling at after distilled. A 90% yield (based upon the 75-80° C. at atmospheric pressure was collected. amount of monamyl triethoxysilane used as a In view of the fact that monoamyl trifluorosilane reactant) of monoamyl trifluorosilane was ob boils at 77° C. and ethyl alcohol boils at 78 C., 30 tained having a boiling range of 74-77 C. at it was difficult to separate them from each other atmospheric pressure. The remaining 10% of by distillation. Hence, the mixture was treated unreacted monoamyl triethoxysilane was re with anhydrous calcium chloride to absorb the covered from the reaction flask, which also con alcohol and the monoamyl trifluorosilane was tained potassium fluoride. decanted from the calcium chloride-ethyl alcohol 35 complex and distilled to yield 89% (based upon Eacample V the amount of monoamyl triethoxysilane en 156 gms, of diamyl diethoxysilane (prepared ployed) of monoamyl trifluorosilane having a in the usual manner by the reaction of ethyl boiling point at atmospheric pressure of 77 C. orthosilicate and amyl magnesium bromide and Eacample II 40 having a boiling range of 145-155° C. at an absolute pressure of 41 mm. of mercury) and To a 500 ml, flask which was equipped with a 50 gms. of potassium polyacid fluoride having reflux condenser and a mechanical stirrer was an available hydrogen fluoride content of 48.5% added 102 gms. of diamyl diethoxysilane (boil by weight were refluxed together for one-half ing point 246° C. at atmospheric pressure) and 45 hour with stirring in a three-necked flask 45gms. of ammonium bifluoride. The contents equipped with a mechanical stirrer and a reflux of the reaction flask were then heated and re Condenser. The reaction products were then fluxed for two hours with stirring, after which distilled directly from the reaction flask and the contents were distilled directly from the re thereafter again distilled at atmospheric pressure action flask at atmospheric pressure, yielding 20 50 using a fractionating column. An almost theo gms. of diamyl difluorosilane having a boiling retical quantity of ethyl alcohol was obtained. range of 193-200° C., 20 gms. Of diamyl mono In addition, there were obtained 60 gms. (a 50% fluoro monoethoxysilane having a boiling range yield based upon the diamyl diethoxysilane en of 200-246° C. and 30 gms. of diamyl diethoxy ployed) of diamyl difluorosilane having a boiling Silane above 246 C. 55 range of 193-200 C., 45 gms, of diamyl mono Eacample III fluoro monoethoxysilane boiling between 200 and 246 C., and 10% of unreacted diamyl diethoxy To a 500 ml., three-necked fiask which was equipped with a reflux condenser and a mechani silane. Eacample VI cal stirrer was added 141 gms. Of phenyl tri 60 ethoxysilane and 23 gms. of potassium polyacid 332 gms. of monolauryl triethoxysilane (pre fluoride having an available hydrogen fluoride pared in the conventional manner by the reaction content of 48.46% by weight. The contents of of ethyl orthosilicate and lauryl magnesium bro the flask were stirred and an exothermic reaction mide) was placed in a three-necked one-liter started, the reaction becoming vigorous upon 65 flask which was fitted with a glass inlet tube and touching the flask with a flame. The contents of a take-off head with a reflux condenser. Anhy the reaction fiask were then refluxed for a short drous hydrogen fluoride was passed through a period of time, after which the contents of the trap and then to the inlet tube of the flask. The flask were distilled. Phenyl trifluorosilane boils addition of the hydrogen fluoride gas was con at 101-102° C. and forms with ethyl alcohol a 70 tinued at a moderate rate and the reaction mix constant boiling mixture distilling at 77° C., and ture became quite hot (70° C.). After approxi in order to separate the silane from the alcohol mately 50 gms. of hydrogen fluoride had been the mixture was treated with cold concentrated added, the reaction may be separated into two sulfuric acid by adding the acid slowly and keep layers, the upper of which was clear and the ing the mixture in an ice bath. Since the alcohol 75 lower of Which was clear but brown in color, The

2,527,288 S 6 contents of the reaction flask were then subjected used as a fluorinating agent, or instead there may to distillation, and 130 gms. of ethyl alcohol was be used materials which under the reaction con recovered at 78° C. (theoretical quantity 138 ditions decompose to form hydrogen fluoride. It gms.). The residue remaining in the flask was is furthermore preferable to conduct the reaction then placed in a copper flask fitted with a frac under anhydrous conditions, in order to reduce tionating column and the residue Was Subjected to a minimum the hydrolysis of the alkoxy com to vacuum distillation. 171 gms. of monolauryl pound and of the fluoride products, and also to trifluorosilane was thus obtained (a 67% yield reduce to a minimum the reaction of hydrogen based upon the amount of monolauryl triethoxy fluoride upon the reaction vessel. The reaction silane employed) having a boiling range of temperature may be varied over a wide range, 98-102° C. at an absolute pressure of 6-7 mm. of as the examples show, and the reaction may be mercury and having a density of 0.9403 gm. per initiated by mild heating, in the event that it cc. at 23° C. and an in at 23° C. of 1.3910. does not initiate itself. Also, depending upon the The foregoing examples illustrate the method particular silicon fluoride which it is desired to of the present invention for the preparation of prepare, it is desirable to choose the silicon alkoxy alkyl, cycloalkyl, aryl and aralkyl silicon fluorides compound so that the alcohol and silicon fluoride by contacting a suitable Silicon alkoxy compound products vary as Widely as possible in their boil with hydrogen fluoride. ing points, thus making them more easily sepa In place of the alkoxy compounds shown in the rated. In any event, however, the Silicon fluoride examples, there may be substituted any com 20 and alcohol may be separated by known chemi pound having the generic formula, cal procedures, as the examples illustrate. RnSi(OR') 4-n I claim: in which R is a saturated acyclic hydrocarbon 1. The method of preparing a compound hav radical having from one to twelve carbon atoms, ing the generic formula a monocycloalkyl radical having from five to 5 RnSiF4-n eight carbon atoms in the ring and having a total which comprises contacting under substantially of not more than tWelve carbon atoms, an aryl anhydrous conditions hydrogen fluoride with a radical having a total of not more than twelve compound having the generic formula carbon atoms or an aralkyl radical having a total of not more than twelve carbon atoms, in 30 is an integer from one to three, and R' is a where R is a radical selected from the group saturated acyclic hydrocarbon radical having consisting of saturated acyclic hydrocarbon radi from one to five carbon atoms. Thus, when R, is cals having from one to twelve carbon atoms, an alkyl radical it may suitably be the methyl, monocycloalkyl radicals having from five to eight ethyl, n-propyl, i-propyl, n-butyl, isobutyl, n 35 carbon atoms in the ring and having a total of amyl, n-hexyl, 2-ethylhexyl, etc. group. R.' may not more than twelve carbon atoms, aryl radi be the methyl, ethyl, n-propyl, i-propyl, n-butyl, cals having a total of not more than twelve carbon n-aml, etc. radical. Hence, suitable specific alkyl atoms and aralkyl radicals having a total of not alkoxy compounds are monomethyl trimethoxy 40 more than twelve carbon atoms, n is an integer Silane, dimethyl dimethoxysilane, trimethyl from one to three, and R' is a saturated acyclic monomethoxysilane, monomethyl triethoxysilane, hydrocarbon radical having from one to five car dimethyl diethoxysilane, trimethyl monoethoxy bon atoms. silane, etc. When R is a monocycloalkyl radi 2. The process of claim 1 in which n is one. cal, it may suitably be the cyclopentyl, cyclohexyl, 3. The process of claim 1 in which n is one cycloheptyl, cyclooctyl, cyclopentylmethyl, cyclo 45 and in which R is an alkyl radical. hexylethyl, cycloheptyl-n-propyl, p-methylcyclo 4. The process of claim 1 in which n is two. hexyl (p-methylcyclohexyl)-methyl, etc. group, 5. The process of claim 1 in which m is two and and suitable Specific cycloalkyl alkoxy silanes in which R is an alkyl radical. which may be used as a reactant are monocyclo 6. The process of claim 1 in which in is three. pentyl trimethoxysilane, dicyclohexyl diethoxy 50 7. The process of claim 1 in which n is three silane, tricycloheptyl monomethoxysilane, cyclo and R is an alkyl radical. pentylmethyl triethoxysilane, di-(p-methylcyclo FRANK. J. SOWA. hexyl)-methyl dimethoxysilane, etc. When R is an aryl radical, it may suitably be the phenyl, REFERENCES CITED O-tolyl, m-tolyl, p-tolyl, O-xylyl, m-xylyl, p-xylyl, 55 The following references are of record in the p-ethylphenyl, cumenyl, mesityl, etc. group, and file of this patent: suitable specific aryl alkoxy silanes which may be used as a reactant are monophenyl trimethoxy UNITED STATES PATENTS silane, di-o-tolyl diethoxysilane, tri-m-xylyl monomethoxysilane, cumenyl tri-n-butoxysilane, 60 Number Name Date di-p-ethylphenyl di-n-propoxysilane, etc. Fur 2,382,082 McGregor ------Aug. 14, 1945 thermore, when R is an aralkyl radical it may 2,386,441 Daudt ------Oct. 9, 1945 suitably be the benzyl, phenylethyl, (p-methyl 2,398,672 Sauer ------Apr. 16, 1946 phenyl)-methyl, (p-ethylphenyl)-ethyl, (3,5-di 2,436,777 Petcher ------Feb. 24, 1948 methylphenyl)-methyl, etc. group, and Suitable 65 2,449,815 Newkirk ------Sept. 21, 1948 specific aralkyl alkoxy Silanes which may be OTHER REFERENCES used as a reactant are monobenzyl trimethoxy Pearlson, “Jour. Amer. Chem. Soc.,' vol. 6 silane, dilbenzyl diethoxysilane, monophenylethyl (1945), pages 1769-1770. tri-n-butoxysilane, tri-(p-methylphenyl)-methyl 70 Flood, “Jour. Amer. Chem. Soc.," vol. 55, (1933), monoethoxysilane, di- (gamma-phenyl) - propyl pages 1735-6. dimethoxysilane, etc. Peppard, “Jour. Amer. Chem. Soc' vol. 68 As the examples show, the hydrogen fluoride (Jan., 1946), pages 76, 77, may be derived from a variety of sources, Thus, the compound hydrogen fluoride alone may be 75 pagesSommer, 445-44 "Jour, Am. Chen, Soc' vol. 70 (1948),