DE1768321C3 - - Google Patents

Description

I. R • C s N + H ₈ -> R • CH =

II. R · C ξ N + 2H ₈ -► R · CH ₂ NH ₈ III. R CH = NH + R CH ₈ NH ₈ -► R CH ₈ NHCH R -> R CH ₈ N = CH R + NH,

NH ₈

This results in summary sizing to be removed. Higher molecular weight compounds

2R · C = N + 3H ₈ ^ R · CH ₈ N = CH · R + NH, genes are only formed in minor amounts and

45 remain in the residue from the distillation.

The ammonia formed can be exhausted by the Schiff's bases obtained in this way

would be removed. With higher molecular weight are valuable intermediate compounds.

Nitriles are worked under normal pressure; short chain. . Nitriles, e.g. B. propionitrile, require the Hy- B e 1 s ρ 1 e 1 1

A slight overpressure drift, if necessary at 5 °. 550 g of propionitrile are placed in an autoclave

Presence of an inert gas, such as nitrogen, around the (= 10 mol) together with 30 g of propionitrilfeuchtem

to reach the required reaction temperature. Raney nickel submitted. Then you press 15 M9I

In unsaturated nitriles, such as tallow hydrogen, and heated to 165 ^° C. for 1 hour

fatty nitrile, the olefinic double bond remains when the contact is separated and the

Hydrogenation practically preserved. 55 ammonia formed over a 50 cm column The reaction was surprising in that about 22% pure propylamine is not obtained as a forerun

It was to be expected that the nitrile group was selectively and 70% of a main fraction, which was made up of 80 parts

can be hydrogenated without the double bond of the di-C ₃ -Schiff base; the remaining 20 parts

Schiff's base, as well as the olefinic base, are propionitrile and dipropylamine. 8% higher mol-

Double bond, is noticeably attacked. 60 kular connections remain in the arrears. Through After the hydrogenation, the contact that can be used for fine fractionation of the main fraction is the pure

several approaches can be used, separated N-propylidene-propylamine, which at bp _7M 100 to

and the reaction mixture obtained is distilled. Un- 102 ⁰ C boils, given off by the nitrile-amine azeotrope

reacted nitrile and primary amine are considered to be separated.

Preliminary cut and can be in the next approach 65.

will be reinstated · !. The B e ι s ρ 1 e I 2 is then distilled

Schiff base in high purity over; possibly in front of 543 g of lauryl nitrile in a glass flask

Existing secondary amine can be moistened by recrystalline (= 3 mol) together with 27 g of cyclohexane

Submitted Raney nickel and hydrogenated at 165 ° C while passing in about 341 hydrogen per hour. In about 4 _^3/4 hour 99.0 normal liters of hydrogen are added (theory for 4.5 mol = 100.8 1) and 19.5 g of ammonia (theory 25.5 g) with the exhaust gas discharged. After the contact has been separated off, the distillation through a Claisen attachment gives 28% first run, consisting of about 42 parts of unreacted nitrile and 58 parts of laurylamine and 66% of the main run, 90% of the Schiff base (N-laurylidene-laurylamine) and 10% of dilaurylamine contains. 6% higher molecular weight compounds remain in the residue.

Example 3

540 g Stearylnitril (= 2.04 mol) are combined with 27 g Raney nickel in a glass flask cyrlohexanfeucht vessel and treated under vigorous stirring with about 301 hydrogen at atmospheric pressure and 165 ^C C, 64.8 normal liters of hydrogen are added in about 5 hours (Theory for 3.06 mol = 68.41) and 132 g of ammonia discharged with the exhaust gas (theory: 17.3 g). The catalyst is filtered off and the filtrate is distilled in an oil pump vacuum through a Claisen attachment. After a preliminary run of about 25%, consisting of 40% unreacted stearyl nitrile and 60% stearylamine, 70% pass at 267 to 330 ° C./0.3 to 0.4 mm, 90% of which consists of Schiff base (N-stearylidene -steai-ylamin) exist. The remainder is distearylamine, which can be removed by recrystallization ·. At a pot temperature of 360 ⁰ C 5% higher molecular weight substances, remain as residue.

Example 1 4.

700 g of a pure C _lg fraction of tallow fatty nitrile (= 2.65 mol) (iodine number: 74) are placed in a flask together with 35 g of Raney nickel cyclohexane and treated at 165 ° C. with about 40 liters of hydrogen per hour with vigorous stirring . In 4 _^3/4 hour 93.7 normal liters of hydrogen are added (3.98 mol theory = 89.11) and 18.1 g

ίο ammonia discharged with the exhaust gas (theory: 22.5 g). After separating the contact, the Claisen distillation yields 26% foreshot, consisting of 35% unreacted nitrile and 65% primary amine and 66% main run, consisting of 90% Schiffscher Base of iodine number 64 and 8% residue.

Example 5

704 g of a mixture of
a) 322 g of fresh stearyl nitrile and
b) 269 g of stearylamine and
lOg stearyinitrile

(both from the forerunner of the previous hydrogenation)

are presented moist together with 35 g of Raney nickel cyclohexanes in a flask and while introducing hydrogenated by about 16.51 hydrogen per hour at 165 ° C. 45.0 normal liters of hydrogen were achieved in 4 hours added and 15.9 g of ammonia discharged with the exhaust gas. After disconnecting the contact the Claisen distillation gives 32% first runnings, consisting of 28% unreacted stearyl nitrile and 72% stearylamine, as well as 63% main run, which consists of 90% Schiff base and 10% distearylamine. The distillation residue is 5%.

Claims (2)

To be able to maintain response. Side reaction claims, such as trimerization and aldol condensation (Ber. 82, p. 316 [1949]) or the formation of higher un- 1. Process for the preparation of Schiff's saturated Schiff's bases (J. Am. Chem. Soc. 63, Basen durch incomplete catalytic hydration 5 p. 872 [1941]; US Pat. No. 2,498,419; Chem. Tion of nitriles in the presence von Raney-Abstr. 44, p. 7865 [1950]), reduce the yield. Nickel, characterized in that Schiff bases also occur in the catalytic! saturated and unsaturated, straight-chain such as production of secondary amines from primary branched nitriles with 1 to 20 carbon atoms amines as intermediates. Is heated, for example in a reaction vessel with vigorous stirring: o a primary amine using Raney nickel, as observed at 100 to 200 ⁰ C as long as hydrogen is behan- an elevating punched in addition to the elimination of ammonia, to 1.5 moles of hydrogen per mole of used borrowed hydrogen evolution; are added in addition to the secondary nitrile. Amin forms the Schiff base (K. Kindler 2. The method according to claim 1, characterized and employees. Ann. 644, pp. 23-30, 1961). Analog is characterized in that hydrogenation is carried out at 150 to 180 ⁰ C. 15 should be the Schiff base in the hydrogenation of the Form nitriles to amines. So far, however, it has not been possible to direct the reaction in such a way that it leads to a economic production of Schiff's bases could be exploited. The invention now relates to a method for the production of Schiff bases by incomplete Schiff bases are used in organic chemistry for the catalytic hydrogenation of nitriles in counter-often as intermediates. They are produced in the manner of Raney nickel, which is generally characterized by the conversion of aldehydes and is characterized by the fact that saturated and unsaturated ketones are combined with primary amines. In order to obtain good yields of straight-chain as well as branched nitriles with 1 to 20 carbon atoms, it is necessary to work lenstoffatomen in a reaction vessel under vigor at low temperature (J. Am. Chem. Soc. 66, p. 93 [1944]). While stirring at 100 to 20O ^{0 C, preferably 150 to 180 0} C in the production of the lower members is hydrogenated in this way, as long as treated with hydrogen does not cause any difficulty, the synthesis must be up to 1.5 moles of hydrogen per mole higher compounds used, which are solid at room temperature, nitrile are added. be worked in the presence of solvents. The following reaction mechanism can be used around the required low temperature during which can be assumed: