The adducts 2D,B,C14 are formed by direct reaction of diboron tetrachloride with D = Me,N, C,H,N, MeCN, and HCN; these are involatile and thermally stable and do not react with olefins. Addition of hydrogen chloride can give diborates, e.g., ~e,NH], [B,Cl,], and the methyl cyanide adduct adds trimethylamine with only partial displacement of the cyanide, suggesting formation of [Me,N],[B,Cl,(CN),]. With D = (CH,*NMe,),, a 1: 1 adduct is formed which is polymeric; with D = N,H4, NH,*NMe,, and (CH,*NH,) 2, elimination of hydrogen chloride as the hydrochloride follows donation and polymeric B-N compounds containing boron-boron bonds are formed. D = Me,NH gives a mixture of B(NMe,),, B,(NMe,),, and polymeric BNMe,.PREVIOUS studies of the reactions of diboron tetrachloride with ammonia and amines and with cyanogen have shown that both boron atoms act as acceptors, giving 2 : 1 adducts. When the donor molecule contains reactive hydrogen, elimination of hydrogen chloride as the hydrochloride of the donor base follows, e.g. :We now report the reactions of diboron tetrachloride with both mono-and bi-dentate nitrogen-donor molecules. EXPERIMENTALDonor substances were prepared (where necessary) by conventional methods and purified by fractionation in the vacuum-system. In a typical reaction, measured amounts of diboron tetrachloride and the donor were mixed a t liquid-nitrogen temperature and the mixture was allowed to warm until reaction was observed (usually at the m. p. of the donor) ; the reaction temperature was kept as low as possible to minimise decomposition of the unchanged diboron tetrachloride. Decomposition was, however, often catalysed by the donor, and hence precise reaction ratios could not always be observed. When reaction was complete, the excess of donor was removed and measured, together with any volatile products which were separated and identified. The reaction product was examined (a) by hydrolysis in a sealed tube (evolved hydrogen and chloride ion were determined, but accurate boron determinations were usually nullified by interference of the donor base in the titrations), (b) by heating it in a sealed tube, volatile products being removed as before, (c) by addition of ethylene or but-2-ene, and ( d ) by addition of hydrogen chloride or trimethylamine. The decomposition of diboron tetrachloride during reaction with a donor yielded boron trichloride and polymeric BCl, the latter being red or yellow; separate experiments indicated that the rate of reaction of (BCl). with a donor was negligibly slow under the conditions used. Hence the main product was contaminated with small amounts of the donor-boron trichloride adduct and with (BCl),. Reaction of an excess B,CI, + 8Me,NH + B,(NMe,), + 4Me,NH,HCI Diboron tetrachloride was prepared and purified as previously described .3Urry, Wartik, Moore, and Schlesinger,

Diboron tetrachloride is stabilised by addition of trichloroethylene ; the nuclear magnetic resonance spectrum of the mixture indicates adduct formation, but no adduct was isolated. Diboron tetrachloride causes polymerisation of isobutene but forms stable 1 : 1 adducts with cis-and trans-but-2-ene. Both of these react with trimethylamine and ammonia in the same way as the ethylene adduct, but oxidation gives 2-chlorobutane and no free olefin. The wide melting ranges of these adducts are attributed to mixtures of rotational isomers, on the basis of their nuclear magnetic resonance spectra.

No abstract

IN the course of an investigation on the halogen derivatives of benzene, we have had occasion to prepare in quantity all the modifications of its di-derivatives containing chlorine and bromine.W e find that orthochlorobromobenzene has not hitherto been described, and the object of the present communication is merely to place its properties on record, The starting point of its preparation was orthonitrobromobenzene ; this was made by nitrating bromobenzene in the cold in the manner described -by Coste and Parry (Bey., 1896, 29, i, 788); this gave very satisfactory results, but we found it most convenient to separate the ortho-and para-compounds by grinding them up in a mortar with small quantities of cold methylated spirits and filtering, repeating the operation until the filtrate became colourless. The orthonitrobromobenzene dissolved, and after the solvent had evaporated was obtained in long needles which melted at 42' after recrystallisation.On reducing the orthonitrobromobenzene to the corresponding bromaniline, Hubner and Alsberg (Anmlen, 1870, 158, 316), and later Fittig and Mager (Bey., 1874, 7, 1179), found great difficulty in obtaining the latter in the solid state; we experienced the same difficulty, which was completely overcome, however, when we added the nitrobromobenzene in alcoholic solution, instead of in the solid state, to the slightly warmed reducing mixture of stannous chloride and hydrochloric acid. On shaking vigorously, the reduction proceeded with development of heat, and after cooling, adding excess of caustic soda and distilling with steam, the oil which came over solidified in the receiver ; after recrystallising, it melted at 32'. To convert the orthobromaniline into orthobromochlorobenzene, it was diazotised in the usual manner, and the solution of the diazocompound added to a warm solution of cuprous chloride. The oil which separated was then distilled over with steam, the distillate

The mother liquors contain oxalic acid and a small qiixntit,y of a We shall now describe in detail the inethod of operating and the nitrogenous acid melting a t 208'. various products obtained, Coiydaline iVit riite. Two litres of dilute nitric acid (1 of acid, sp. gr. 1.42, t o 20 of water) are heated on the water bath and 10 grams of the powdered alkaloid gradually added. The sparingly soluble nitrate which is immediately formed is very insoluble in cold, and soluble with difficulty in hot water, but more readily in the presence of frec nitric acid. It forms thick, tabular crystals without water of crystallisation. Dried a t 1 OW, it yielded the following results on analysis : C = 60.53 ; IT = 7.09. I. 0.2015 gave 0.4472 CO, and 0.12S7 II,O. 11. 0.1659 ,, 9.5 C.C. nitrogen a t 10" a i~d 75s nim. N = 6-92.