DE1216870B - Process for the preparation of cyclohexylamine diborate - Google Patents

Description

Process for the preparation of cyclohexylamine diborate A process for the preparation of cyclohexylamine diborate by reacting cyclohexylamine with boric acid according to the equation has already been described in US Pat. No. 2,710,401 CGHiiNH2 -f- 2 H, B03 -> C6HiiNH2 ' B203 - H20 + 2 H20 described. This process has proven to be unsuitable for large-scale production for a number of reasons. So it is necessary to use a large excess of cyclohexylamine and also an organic diluent, e.g. B. toluene to be used to facilitate the filtration of the reaction product. However, the water formed during the reaction is found in the filtrate together with excess amine and the diluent. Although it would be economically very desirable to reuse the filtrate for further batches in order to recycle the unreacted reactants, this prevents the continuous formation of water.

Cyclohexylamine diborate is used as an anti-corrosive agent.

The invention therefore provides a process for the production of Diborates of cyclohexylamine, which does not have these disadvantages.

According to the invention, cyclohexylamine diborate is made by heating cyclohexylamine with a mixture of boric anhydride and boric acid in an almost equimolecular ratio or made with metaboric acid (H, B204).

The reaction taking place when using equimolecular amounts of boric anhydride and boric acid can be given by equation 3 C, H "NH2 - (- 2 li, BO3 - (- 2 B203 -> 3 C6Hr, NH2 ' B203 ' H20 being represented.

The cyclohexylamine is preferably in excess, e.g. B. in 1.5 to 6 times, preferably 2 to 6 times, the theoretical for the reaction with the Mixture of boric anhydride and boric acid required to produce a diborate Crowd present. If you use significantly less than twice the theoretical Amount, then the product often contains more than the theoretical amount of boric anhydride, mostly in bound form. In the reaction with metaboric acid there is a smaller excess of amine required, and the cyclohexylamine is preferably used in one Amount up to 2 times, preferably up to about 1, lfold the theoretical for the Reaction with metaboric acid amount required to produce a diborate.

The process is preferably carried out in a liquid reaction medium by, especially in the approximate minimum amount required, to the reactants be able to mix effectively and easily with a stirrer or the like. This is preferably used an aliphatic or aromatic hydrocarbon or a chlorinated hydrocarbon, especially a light petrol. The liquid medium used is usually sufficient volatile to easily formed by distillation and condensation of the cyclohexylamine diborate to be separated and reclaimed.

The temperature used is not critical, one often works expediently at the reflux temperature of the reaction medium. In general are temperatures between about 20 and about 150 ° C, in particular between about 60 and about 100 ° C.

After the reaction has largely ended, the volatile constituents can of the mixture, in particular unchanged amine and the liquid reaction medium, removed by heating the product in vacuo and by condensation in a Cold trap to be caught. Since these are largely free of water, you can them after the addition of the stoichiometric amounts of amine, boric anhydride and boric acid and or or. Metaboric acid can be returned to the process. The process according to the invention is explained in more detail using the following examples.

Example 1 Cyclohexylamine C, H "NH2, boric anhydride and boric acid in a molar ratio of 3: 1: 1 were mixed with light gasoline (b.p. 60 to 80 ° C.) and heated to moderate boiling for 2 hours with stirring and reflux. The reaction vessel was then heated The temperature was then increased again to about 70 ° C. in order to distill off the volatile substances. These were condensed in a cold trap. The solid residue of cyclohexylamine diborate gave the following analysis values: CBH "NH2 51.36 0/0 , B203 37.72 0/0, H20 10.92 0/0. 1.0: 1.4: 1.17 molar ratio.

Yield (based on B203): 96.5%.

The unchanged cyclohexylamine and the light gasoline became quantitative recovered and could after the addition of amine, boric anhydride and boric acid. in the molar ratios 1: 0.66: 0.66 in a new approach to the production of cyclohexylamine diborate be used.

Example 2 198.3 g (2 mol) of cyclohexylamine and 87.44 g (1 mol) of metaboric acid were mixed with 150 ml of light petrol (boiling point 80 to 100 ° C.). The mixture was heated to 70.degree. C. for 1/2 hour with stirring, whereupon the mixture suddenly reacted and solidified. After adding a further 150 ml of light gasoline, the mixture could be stirred again and was heated to moderate boiling for 21/2 hours with stirring and under reflux. The volatile substances were removed in vacuo. The product was finally dried at 80 ° C. in a drying cabinet. The analysis of the residue was as follows: CsH11NH2 51.170 / 0, B203 37.830 / 0, H20.110 / 0 molar ratio 1: 1.05: 1.18.

Yield: 176 g (94.2%). Example 3 275 g (2.78 moles) of cyclohexylamine and 221 g (2.52 moles) of metaboric acid were mixed in a flask equipped with a stirrer and reflux condenser, and then the slurry was heated with stirring in an oil bath. At a bath temperature of 75 ° C., the slurry quickly became thick and could not be stirred any further. A very violent reaction started and the cyclohexylamine boiled violently. The reaction mixture was heated to 80 to 90 ° C. for a further 2 hours, after which the reaction product was removed from the flask and dried at 90 ° C. in a drying cabinet. The analysis. this product gave the following values: C6H11NH2 52.810 / 0, B203 38.89%, H20 8.300 / 0. Molar ratio 1: 1.06: 0.88.

Yield: 455 g (97.20 / 0). Example 14 825 g (8.32 moles) cyclohexylamine and 633 g (7.55 mol) of metaboric acid were in a with stirrer and reflux condenser equipped flask and mixed into the slurry 584 g of the reaction product registered. The mass became so thick that the metaboric acid remained even after it had been interrupted of stirring is sufficient.

The mixture was then heated in a water bath with stirring, with the slurry thickened very quickly at 70 ° C and could no longer be stirred could. A vigorous reaction set in, with the cyclohexylamine being slightly underdeveloped. Refluxed. The flask was heated to 90 to 95 ° C for an additional 2 hours, whereupon the reaction product was removed from the flask and placed in a drying cabinet at 80.degree dried.

The analysis of the reaction product gave the following values: C, H "NII2 52.93 0/0, B203 28.14 0/0, H20 8.93 0/0. Molar ratio 1: 1.03: 0.90.

Yield: 1346 g (95.30 / 0).

Claims (4)

Claims: 1. Process - for the production of cyclohexylamine diborate by reacting preferably excess cyclohexylamine with boric acid, if desired in the presence of an organic diluent, thereby g e k e n n nz e i c h n e t that almost equimolecular mixtures of boric acid are used instead of boric acid and boric anhydride or metaboric acid is used. 2. The method according to claim 1, characterized in that 2 to 6 times the theoretical for the reaction with the mixture of boric anhydride and boric acid to produce a diborate required amount of cyclohexylamine or about twice the theoretical for the reaction with metaboric acid required to produce the diborate used on cyclohexylamine. 3. The method according to claim 1 and 2, characterized in that that up to about 1, lfold the theoretically required amount of cyclohexylamine used. 4. The method according to claim 1 to 3, characterized in that as Diluent used an aliphatic hydrocarbon.