DE1139822B - Process for the production of organic sub-boric acid esters - Google Patents

Description

Process for the preparation of organic subboric acid esters The invention relates to a process for the preparation of organic subboric acid esters, that have boron-boron bonds.

Subboric acid esters B2 (0 R) 4 have already been implemented by E. Wiberg of chloroboric acid esters with sodium amalgan (see K. A. Hofmann, Inorganic Chemie, 1955, p. 403, last paragraph.) In contrast, the process exists for the production of organic subboric acid esters containing a boron-boron bond, according to the present invention in that a tetraalkylaminodiboron or tetraarylaminodiboron, which is derived from a primary or secondary amine, with an alcohol, a phenol or an 8-oxyquinoline is reacted. Reactions of those just mentioned Art can be represented by the following equation: 4 R'OH + B2 (NR "2) 4 = B2 (0R ') 4 + 4 R "2NH In this R 'OH represents an alcohol or a phenol or 8-hydroxyquinoline and B2 (NR "2) 4 is a dibortetraalkylamine or a dibortetraarylamine, which is derived from a primary or secondary amine. The organic subboric acid esters, which are formed by reactions of the type mentioned are subboric acid tetraalkyl esters, Suboric acid tetraaryl ester or suboric acid tetra-8-quinoline ester, and the invention also refers to the last-mentioned compounds as well as additionally to the subboric acid tetraphenyl ester, which are new as such.

Some specific examples of the boron-containing reactants B2 (N R "2) that can be used are those that can be used as NR" 2 groups as follows Groups contain: methylamino, ethylamino, isopropylamino, n-hexylamino, dimethylamino, Diethylamino, diisopropylamino, di-n-hexylamino, anilino, p-toluidino, l-naphthylamino and diphenylamino groups. For reasons of cheapness and easy availability however, dibortetraalkylamino compounds whose amino groups differ from secondary ones are preferred Derive alkylamines and their alkyl groups contain 1 to 6 carbon atoms, Dibortetradimethylamine is particularly mentioned.

The other reactant can be any primary, secondary or tertiary alcohol, any phenol, or an 8-hydroxyquinoline. It should be on it it should be noted that the phenol, as it is here in the present specification used also include fused ring phenols and mononuclear phenols target. Some specific examples of hydroxy compounds that act as reactants can be used are: all alcohols with 1 to 8 carbon including atoms of matter all isomers of alcohols above ethanol, phenol, cresols, xylenols, Mesitol, catechol, o; -naphthol and 8-hydroxyquinoline.

It has been found that the yields from the general given above Response can be increased considerably and that responses in much less time can be terminated and carried out at considerably lower temperatures can be if an anhydrous hydrogen halide such as anhydrous H Cl, H Br or HF is added.

It has also been found that the addition of any of the above anhydrous hydrogen halides weakens the bond between boron and nitrogen thus making it easier for the hydroxyl radical to replace the amino radical. Of the Hydrogen halide combines with the amine (R "2NH in the above-mentioned equation), which is set free in the reaction in question, so that a substituted Ammonium halide forms as a by-product in place of a free amine.

Preferably, the reactants involved should essentially be in stoichiometric amounts can be used. By this it is meant that although that Exact molar ratio does not have to be given, the reactants only in a small amount Excess or a small deficit are to be used.

An excess of alcohol, phenol or 8-hydroxyquinoline or of hydrogen halide causes a Cleavage of the boron-boron bond, and the greater the excess the greater the cleavage, thereby reducing the yield of the desired product is reduced. In the opposite sense, a deficit of the reactants has the effect that the reaction does not end.

It is therefore advantageous to use 1 mol in the reaction according to the invention of the reactant containing the boron bond with essentially 4 moles of that of the hydroxy compound containing reactants and optionally 4 moles of hydrogen halide to be used.

The sub-boric acid alkyl esters or sub-boric acid aryl esters and sub-boric acid 8-quinoline esters can be in the process according to the present invention with good yields and obtained in an economical and effective manner. You will, among other things used as herbicides and as intermediates in chemical synthesis. aside from that they can be converted into polymeric substances by heating, at least contain five boron-boron bonds and resinous - B (O R) groups.

The following examples are intended to illustrate the invention.

Example I 4.27 g = 21.6 millimoles of dibortetradimethylamine were added to a solution of 3.97 g = 86.4 millimoles of absolute ethanol in 25 ml of hexane. The reaction mixture is heated to 40 to 50 ° C. while stirring vigorously, and the dimethylamine which forms is with a stream of dry nitrogen in a Rinsed 0.5N hydrochloric acid solution. After essentially all of the dimethylamine after about 135 hours has volatilized and recovered, the hexane becomes removed by distillation under reduced pressure. The residue then becomes fast distilled at about 43 to 53 "C and 2 mm pressure.

The distillate obtained, consisting of a mixture of ethyl borate and subboric acid tetraethyl ester, was then slowly at room temperature and 10-6 mm pressure fractionated in vacuo, with pure subboric acid tetraethyl ester with a Boiling point of 20 to 21 "C at 0.1 to 0.2 mm and n204 = 1.3960.

The analysis for B2 (eth) is: Calculated ... B 10.70, C 47.60, H 9.99o1o; found ... B 10.50, C 47.56, H9.91% A cryoscopic molecular weight determination in benzene in an atmosphere of dry nitrogen gave a molecular weight which substantially agrees with the calculated molecular weight, 201.7.

The above-mentioned subboric acid tetraethyl ester forms after about 6 hours Heating to 50 "C a polymeric, viscous, yellow liquid, which with further heating solidifies to about 100 "C.

Example II 4.2058 g = 21.27 millimoles of dibortetradimethylamine cooled to 800 C and treated with 5 ml = 85.8 millimoles of ethanol. This mixture will be with vigorous stirring 29.8 ml = 85.08 millimoles of a previously prepared solution of hydrochloric acid in diethyl ether added. Stirring continues for about 1 hour, whereupon the mixture solidifies. The mixture is then slowly warmed to O "C and stirred for about another hour, after which the Reaction mass filtered will. All of the dimethylamine was found to be essentially dimethylamine hydrochloride dejected at the end of that time.

It should be noted that in Example I the dimethylamine approximately It took 135 hours to evaporate, which is the case in the present example the presence of H Cl causes the dimethylamine to be essentially complete precipitates as the hydrochloride in only about an hour at 0 ° C.

The pure subboric acid tetraethyl ester is then fractionated by vacuum of the filtrate obtained as in Example 1.

Example III The reaction of dibortetradimethylamine with methanol in a molar ratio of 1: 4 was, as described above, in the presence of 4 moles of anhydrous HBr carried out. The reaction was kept at -80 ° C. for 1 hour and the resulting precipitate is then filtered. The filtrate was as above in the Examples I and II distilled. The resulting fabric was essentially purer Subboric acid tetramethyl ester.

Example IV A diethyl ether solution of 4.00 g = 20.21 millimoles of dibortetradimethylamine and 4.85 g = 80.84 millimoles of isopropyl alcohol was cooled to -85 "C and 80.84 Millimoles of anhydrous hydrochloric acid in 37.6 ml of diethyl ether solution within 15 minutes added.

Precipitates formed and the resulting pulp was used for stirred for about another 45 minutes.

The mixture was then warmed to 0 ° C and stirring for about 1 hour continued. The precipitates were then filtered off. The solvent was removed from the filtrate by rapid distillation at 2 mm so that a Yield of 71.6% tetraisopropyl subborate, n2D = 1.3970.

The analysis for C12 H28 04B2 is: Calculated ... B = 8.39 01o; Molecular weight 258.0; found ... B = 8.22%; Molecular weight 261.5.

Example V A solution of 0.46 g = 2.32 millimoles of dibortetradimethylamine and 1.35 g = 9.31 millimoles of 8-hydroxyquinoline in 30 ml of benzene was heated to 75 to 80 "C warmed up. The resulting dimethylamine was blown with a stream of dry nitrogen converted into normal H Cl. About 930 per cent of the theoretical amount of the amine was obtained so in about 6 hours away.

During this time the remaining reaction mass transformed from a yellow solution to an orange-brown solid-liquid mixture. The mixture was cooled and filtered. The orange solid obtained was shown through the analysis as subboric acid tetra-8-quinoline ester, C38 H24 04 N4 B2.

Example VI A solution of 6.14 grams = 63.0 millimoles of phenol and 3.23 g = 16.0 millimoles of dibortetradimethylamine in 75 ml of toluene was heated to 100.degree and the resulting dimethylamine with a stream of dry nitrogen in normal H Transferred to Cl. After about 6 hours there was essentially all of the dimethylamine removed. The solvent was distilled off in vacuo, whereupon a brown Ö1 remained. By treating the brown oil (boiling range 20th up to 40 "C) with petroleum ether, tetraphenyl subboric acid was obtained.

Claims (3)

PATENT CLAIMS: 1. Process for the production of organic subboric acid esters, which contain a boron-boron bond, characterized in that a dibortetraalkylamine or dibortetraarylamine, which is derived from a primary or secondary amine, preferably a dibortetradialkylamine whose alkyl radicals have 1 to 6 carbon atoms contain, in particular dibortetradimethylamine with an alcohol, a phenol or 8-Hydroxyquinoline, preferably implemented in a substantially molar ratio of 1: 4 will. 2. The method according to claim 1, characterized in that in addition to the two reactants mentioned in claim 1 an anhydrous hydrogen halide except hydrogen iodide is used, preferably in a ratio of 4 moles per mole of the reactant containing the boron. 3. The method according to claim 1 and 2, characterized in that the the reactants containing the hydroxy compound, ethanol, methanol, isopropanol or phenol. Publications considered: K. A. Hofmann, textbook of inorganic chemistry, 1955, p. 403.