Boron chloride-trimethylamine

The apparatus used is the same as that described above, except that 200 ml. of dry benzene is placed in the flask and the gas delivery tubes are adjusted to project slightly below the surface of the benzene. The boron chloride delivery tube should be at least 9 mm. in diameter. J Trimethylamine is admitted to the reaction vessel at such a rate as to produce moderate bubbling in the bubbler. Boron chloride is then admitted, and its rate of flow is adjusted as before so that no net flow of gas out of the flask results. As the reaction proceeds, the product separates from the benzene layer as white crystals. The reaction is allowed to continue until the desired quantity of product is 

Boron fluoride-trimethylamine is a white, crystalline solid melting in a closed tube at 138°.3 The vapor pressure of the solid is given by the equation4 

From these relationships, the following values are obtained 4 heat of fusion, 3.5 kcal./mol normal boiling point, 233° Trouton s constant, 25.5 cal./deg. mol. The liquid and vapor are both associated.4 Cryoscopic measurements upon benzene solutions give apparent molecular weights ranging from 158 (mol fraction = 0.0016) to 230 (mol fraction = 0.0060). At room temperature the solubility of the compound in benzene is 0.995 g./lOO g. of solvent.3 

Boron chloride-trimethylamine is a white, crystalline solid melting at 242 to 243°.6 It is insoluble in benzene but soluble in hot ethanol. It sublimes in high vacuum.6 

These two compounds are among the thermally more stable boron halide-amine compounds. Compounds derived from certain primary and secondary amines lose hydrogen halides at elevated temperatures to give condensed boron-imide or borazole (borazine) derivatives. 

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Borazole (borazine), derivatives of, from boron halide-amine coordination compounds, 5 28 Boric acid, H3BO3, esters of, 6 29 Boron bromide, 3 27, 29 Boron chloride, 3 27, 28, 29 Boron chloride-trimethylamine, 6 27... 

BC1j-(CH3)3N Boron chloride-trimethylamine, 5 27 BF3 Boron fluoride, 1 21, 23 compound with hexamethyl-... 

Trimethylamine replaces PH3 quantitatively in BH3 PH3 to give BH3 N(CH3)3. Liquid or gaseous ammonia also replaces phosphine in the compound BH3 PH3 to the extent of 52-58% or up to 75%, respectively. The hydrogen atoms bonded to boron are partially, or completely, replaced by chlorine on treatment with hydrogen chloride, depending on the reaction conditions. The first stage of the reaction with hydrogen chloride is the formation of the colourless, viscous liquid BHjCl PH3 (see below). 

The groups of Trost and coworkers and Caserio and coworkers independently developed procedures for azasulfenylation. Caserio reported that when alkenes are treated with a sulfenamide such as MeSN-Me2 in the presence of the Meerwein reagent trimethyloxonium tetrafluoroborate, azasulfenylation of the alkene is observed, presumably via the thioammonium ion MeSNMe3+ (equation 4).20 Boron trifluoride etherate can also serve as a catalyst for addition of sulfenamides to alkenes. The adduct stereochemistry is strictly anti as established by treatment of the dihydropyran methanesulfenyl chloride adduct (see Scheme 2) with AgBF4 followed by trimethylamine. 

Trimetaphosphimic acid, 6 79 Trimethylamine, coordination compounds with boron fluoride and chloride, 5 26, 27 purification of, 2 159 Trimethylamine-sulfur dioxide, 2 159... 

The addition compound of trimethylamine and monochloro-borane was first synthesized by the reaction of gaseous hydrogen chloride with trimethylamine-borane at low temperature in a vacuum line. Although boron trichloride4 or mereury(II) chloride5 can be used, the first method can easily be modified for large-scale runs by using aqueous concentrated hydrochloric acid.5 No special precautions for the exclusion of air or water are necessary. 

Borane, which is used as a complex with tetrahydrofuran [992] or dimethyl sulfide [611, 992] or generated in situ from lithium borohydride with boron trifluoride etherate [646] or sodium borohydride with aluminum chloride [184], reacts with 3 mol of an alkene to form a tertiary borane. The oxidation with alkaline hydrogen peroxide [183, 992, 1201] or with trimethylamine oxide [991, 992] yields an alcohol (equations 598 and 599). 

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