United States Patent Office Patented Oct
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3,347,931 United States Patent Office Patented Oct. 17, 1967 1. 2 halogenated aromatics as benzyl chloride, phenylbromo 3,347,931 PRE PARATION OF ORGANOBORON pentane, chlorobenzene, xylyl chloride, chlorotetramethyl COMPOUNDS benzene, iodoheptylbenzene, 1 - chloro-2-phenylethylene Paul R. Wunz, Jr., Richland Township, and Albert F. and the like. Typical cycloaliphatic halides include cyclo Stang, Harmony, Pa., assignors to Callery. Chemical 5 hexyl chloride and cyclopentyl bromide, while examples Company, Pittsburgh, Pa., a corporation of Pennsyl of aliphatic halides are chloroprene, allyl bromide, vinyl vania chloride, dodecyl bromide, octadecyl chloride and the like. No Drawing. Fied Aug. 14, 1958, Ser. No. 756,058 The compounds corresponding to the foregoing but con - 17 Claims. (CI. 260-606.5) taining a plurality of halogens can also be used. For ex 0 ample we have successfully used compounds such as car This application is a continuation-in-part of our applica bon tetrachloride and 1,3-dichloropropane as a reactant tion Serial Number 484,586, filed January 27, 1955, now to obtain boron hydride derivatives. While any of the abandoned. halogens may be present in the halogenated hydrocarbons, This invention relates to the preparation of organoboron chlorides and bromides generally are preferred for reasons compounds, and in particular it relates to the preparation 5 of economics and handling considerations. of organoboron compounds upon reaction of an alkene In the process involving the hydrides and alkenes, while and halogenated organic compounds with volatile boron any alkene may be used, it is generally preferred to use hydrides having at least four boron atoms per molecule. alkenes with a maximum of about 25 carbon atoms, and . It is an object of this invention to provide a method usually not more than 15 carbon atoms, per molecule for for preparing organoboron compounds that may be classed 20 they include the most common materials. Typical alkenes as derivatives of volatile higher boron hydrides. are ethylene, propene, hexene, methylbutylene, butadiene, Another object of the invention is to provide a method 1-propyl-3-decene, octadecylene and the like. for preparing organoboron compounds such as hydrocar The reactions in accordance with this invention are bon-boron compounds in accordance with the foregoing carried out in the presence of an aluminum halide catalyst. object by which a variety of hitherto unknown boron 25 Aluminum chloride and aluminum bromide are two espe containing organic compounds can be prepared. cially suitable catalyst. These are materials of commerce A specific object is to provide an improved method for and the commercially available proprietary catalysts of preparing aliphatic hydrocarbon derivatives of volatile this general type usually may be used as such in practicing higher boron hydrides. this invention. An additional specific object is to provide new alkylated 30 boron hydrides having at least four baron atoms per mole The invention will be described further in conjunction cule. with the following examples. It should be understood that These and other objects are attained with our discovery the details disclosed are given by way of illustration. that volatile higher boronhydrides react with halogenated Example I hydrocarbons in the presence of an aluminum halide and 35 thereby from organoboron compounds. We have also dis Monoethyldecaborane (C2H5B10H13) was prepared by covered that an aluminum halide will catalyze the reaction reacting ethyl bromide and decaborane in the presence of of volatile higher boron hydrides and alkenes thereby aluminum chloride using carbon disulfide as a solvent. A forming alkyl derivatives of these boron hydrides. In the 3-necked, round bottomed flask fitted with a magnetic foregoing manner, a variety of organoboron compounds 40 stirrer, reflux condenser thermometer and dropping funnel can be readily produced. Moreover, alkyl derivatives of was charged with 13.4 g (0.11 mol) of decaborane, 6 g. volatile higher boron hydrides can be produced under of aluminum chloride and 125 ml. of carbon disulfide. more moderate conditions than was heretofore possible. The dropping funnel was charged with 10.9 g (0.10 mol) The boron containing reactants that are used in our in of ethyl bromide. The contents of the flask were warmed vention are volatile higher boron hydrides containing 4 to 45 to the reflux temperature of CS, and the CHBr was 12 boron atoms per molecule. Examples of these hydrides added dropwise. Gas was evolved during the reaction. include tetraborane, pentaborane-9, pentaborane-11, hexa The reaction was complete in 4 hours. The product was borane and decaborane. The hydrides can be used in sub cooled and poured on cracked ice to decompose the AlCls. stantially pure form. However, mixtures of the hydrides The solvent layer was removed, washed and dried and as obtained, for example, by a pyrolysis of diborane, are 50 the CS2 removed under vacuum. About 3.7 g. of unreacted generally a more economical starting material and consti decaborane were removed by filtration. The crude filtrate, tute the preferred reactant for many purposes, e.g. where which weighed 10.1 g., was analyzed and found to con the identity of the product species is not of primary im tain no aluminum, halogen or sulfur. The boron and portance, as in a fuel application. It should be understood carbon content expressed in milligram atoms per gram. that materials other than the hydrides may be present was as follows: along with this reactant as long as they do not interfere deleteriously with this invention. Calculated The halogenated organic compounds that are used in Found the invention are halogenated hydrocarbons wherein the C.H. BioEI13 (CEIs) Biodia hydrocarbon portion of the molecule can be. aromatic, cycloaliphatic or aliphatic, and combinations of the fore 66.7 56.2 62.8 going such as cyclic hydrocarbons containing one or more 13.3 22.4 16.7 side chains. These compounds can be saturated or un saturated, the latter in the rings or side chains or both. 65 This analysis indicates that a mixture of monoethyldec While the number or disposition of carbon atoms present aborane and diethyldecaborane was formed in the above is not known to affect this invention, for most purposes reaction. Distillation of this product through a falling film. compounds containing a maximum of about 25 and suit molecular still yielded two major fractions which are ably 18 carbon atoms per molecule are used. Typical halo monoethyldecaborane and diethyldecaborane, respec genated hydrocarbons include, by way of example, such tively. 3,347,931 4. 3. and the halogen from the halide reactant, hydrogen halide being split out. Fraction 1 Fraction 2 Similar reactions can be carried out with the other CH5B10H13 (C2H5)2B1012 halogenated hydrocarbons and the volatile higher boron Analysis: hydrides in the presence of aluminum halides in the Boron--------------------- 65.1 56.0 manner of the representative examples above. Where the Carbon------------------- 4.6 20.8 halogenated hydrocarbons are solid, it generally is de Density at 25 C. ing.fml ----- 0.788 0.830 sirable to use a solvent and higher temperatures to facili tate contact and speed the reaction. The temperatures used Example II should, of course, take into account the pyrolysis tem Dimethyldecaborane (CH3)2B10H12, was prepared in a O perature of the borane used, for if the temperature be fashion similar to that in Example I by the action of comes excessive some of the borane will be degraded and methyl bromide on decaborane in the presence of AlBra otherwise be unavailable for the intended reaction, there using CS2 as a solvent. A mixture of 12.2 g (0.1 mol) by decreasing the yield of the desired product. Generally of decaborane, 10 g. of AlBra and 100 ml. of CS was temperatures up to about 150 to 200° C. and higher heated to the reflux temperature of CS and sparged with 5 are used. Similarly, while subatmospheric, atmospheric or 19 g. (0.2 mol) of methyl bromide. The reaction was superatmospheric pressures can be used, this condition of complete in 3% hours after which the product was reaction also is chosen with a view to facilitating the worked up as in the previous example. A 60% yield of a reaction. For example, with the more volatile halides liquid product was obtained which analyzed 61.8 milli and boranes, it is usual to conduct the reaction under gram atoms per gram of boron and 14.4 milligram atoms 20 autogenous pressure. per gram of carbon which corresponds to the theoretical The examples also show that the reaction can be boron and carbon content of dimethyldecaborane. carried out in a solvent as well as in the absence of a Example III solvent. A practice that we have found satisfactory in 25 volves using the halogenated hydrocarbon itself as a In this run, 6 g. (0.05 mol) of decaborane, 33 g (0.30 solvent, when it is liquid at normal conditions or be mol) ethyl bromide, and 1 g. AICl were reacted to comes liquid at the conditions of reaction. This embodi gether at room temperature for six hours in the absence ment involves simply using a large excess of halogenated of solvent. A vigorous reaction took place accompanied hydrocarbon relative to the boron hydride present, or by by the evolution of gas. The reaction mixture was mixed 30 providing both an alkene and halogenated hydrocarbon with water to hydrolyze the AlCl4 present. The excess in the system. The excess then serves as the reaction ethyl bromide was removed and a liquid product obtained medium; it also facilitates consumption of all the hydride which analyzed B 43.2 mga./g. and C 34.8 mga./g. This added thereby resulting in a high efficiency. The reactants, analysis corresponds, within experimental error, to the as a rule, are used in a molar ratio of about 0.2 to 5 analysis for tetraethyldecaborane, (C2H5) BioHo.