Manufacture of substituted glycinonitriles

R²

R¹

R-

NH

(II)

Environmental protection and wastewater treatment, unsatisfactory. It has now been found that N-alkylglycinnitriles of the general formula

in

in the R¹ and R² may be the same or different and each represents an optionally substituted by alkoxy groups having 1 to 4 carbon atoms substituted alkyl group having 1 to 10 carbon atoms and R² also may denote a hydrogen atom, by reacting amines of the general formula

15

20

25

The invention relates to a process for the preparation of N-alkylglycinnitriles by reacting alkylamines with formaldehyde and hydrogen cyanide under certain reaction conditions with respect to temperature, reaction time and hydrogen cyanide concentration.

It is known from DE-PS 6 56 350 that it is possible to convert glycolsitrile with an excess of methylamine 4 * 3 in aqueous solution under pressure to sarcosine nitrile. In order to achieve good yields of sarcosine nitrile, an excess of up to 10 moles of methylamine per mole of oxyacetonitrile is recommended (DE-PS 6 56 350). When stoichiometric amounts are used, the difficult to remove nitrile of methyl diglycolamide acid is produced in considerable quantities.

Another way to prepare N-alkyl substituted glycine nitriles is from formaldehyde in the presence of sodium bisulfite compounds and reacting the aldehyde with sodium cyanide and aliphatic amines. The procedure with sodium cyanide and sodium bisulfite provides by-products for environmental engineering problems by the formation of alkali salts, which may contain residual cyanides, as by-products._b0 It is also known that the amines used in the form of salts, for. As chloride, use (Jean M a thieu and Jean Weil Raynal, Formation of CC bonds, Vol I, pages 442 to 446 [Georg Thieme Verlag Stuttgart 1973]).

All of these methods are in terms of simple and economical operation, good yield of end product and easy workup, especially with respect to R¹

N-CH.-CN

(D

R²

in the R¹ and R^J may be the same or different and each represents an optionally substituted by alkoxy groups having 1 to 4 carbon atoms substituted alkyl group having 1 to 10 carbon atoms and R² also may denote a hydrogen atom, by reacting amines of the general formula

R¹

NH

(H)

R²

in the R¹ and R² have the abovementioned meanings, with formaldehyde and hydrocyanic acid in the presence of water, characterized in that the reaction during 0.1 to 4 _J0 Hours at a temperature of 0 to 40⁰C passes while the concentration of hydrogen cyanide during the reaction to not more than 0.1 percent by weight, based on the reaction mixture, holds 3;

in the R¹ and R² the above meanings, with formaldehyde and hydrocyanic acid in the presence of water, mentioned advantageous, if the reaction for 0.1 to 4 hours at a temperature of 0 to 40⁰C while maintaining the concentration of hydrogen cyanide during the reaction to not more than 0.1 percent by weight, based on the reaction mixture

The reaction can be represented by the following formulas in the case of using dimethylamine:

CH,

H₂CO + Ν-Η + HCN CH₃

'N-CH₂-CN + H₂O

CH₃

Compared with the known processes, the process according to the invention provides N-alkylglycinnitriles in better yield and purity in a simpler and more economical way. The process is comparatively straightforward for large-scale operation and for continuous operation, offers no significant wastewater issues and is environmentally friendly , By-products, eg. B. Nitriles of alkyl diglycolamic acids or methylamines due to the presence of formaldehyde do not occur to any appreciable extent. All these advantageous properties are surprising in view of the prior art.

Formaldehyde can be used in liquid form or as a gas, generally in the form of its aqueous, suitably from 10 to 50, preferably from 30 to 40gewichtsprozentigen solution. Hydrocyanic acid is suitable as a gas or expediently in liquid form. The starting amine II can be used alone or expediently in solution, preferably in aqueous solution; are appropriate 40 to 60gewichtsprozentige

Solutions, You can react the three starting materials in stoichiometric amount or each of the components in each case in excess, preferably in an amount of 0.1 to 2 moles of amine and / or from 0.01 to 0.1 moles of hydrogen cyanide per mole of formaldehyde (calculated 100 %), Preferred starting materials II and accordingly preferred end substances I are those in whose formulas R 'and R² may be the same or different and each represents an alkyl radical having 1 to 8, in particular 1 to 4, carbon atoms, R² in addition, can also denote a hydrogen atom.

It come z. B. as starting materials II into consideration: Methyl, ethyl, n-propyl, isopropyl, η-butyl, isobutyl, selc-butyl, tert-butyl, pentyl, pentyl (2), pentyl (3), n -Hexyl, iv-heptyl, n-octyl, n-nonyl, n-decyl, 2-ethylhexyl, ^, e-trimethyl-n-pentyl - ^ - ethylpentyl, 3-ethylpenty! -, 2 ^ -dimethyl-n-butyl, ^ -dimetbj-n-butyl-methylpentyl, 3-methylpentyl, ZAE-trimethylpentyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 3-ethylhexyl , 2'-dimethylhexyl, 23-dimethylhexyl, 2,4-dimethylhexyl, 2'-dimethyl-hexyl, 33-dimethylhexyl, 3,4-dimethylhexyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, 2,23-trimethylpentyl, 2,2,4-trimethylpentyl, 2A3- Trimethylpentyl, 23,4-trimethylpentyl, 2ä33-tetraethyl-butyl-amine; di (methyl), di (ethyl), di (n-prop...), Di-friopropyl), di-methyl (n-butyl) -, di- (isobutyl) -, di- (selc-butyl) -, di- (tert-butyl) di- (pentyl) -, di- (pentyl) - (2) -, di - (pentyl) - (3) -. Di- (n-hexyl) -, di (n-heptyl) -, di- (n-octyl) -, di (n-nonyl) -, di- (n-decyl) -, di- {2-ethylhexyl ), Di (2,2,6-trimethyl-n-pentyl), di (2-ethylpentyl), di (3-ethylpentyl), di (2,3-dimethyl-n-butyl) ), Di- (2,2-dimethyln-butyl) -, di- (2-methylpentyl) -, di (3-methylpentyl) -, di- (2,2,4-trimethylpentyl) -, di- ( 2-methylheptyl) -, di- (3-methylheptyl) -, di- (4-methylheptyl) -, di- (3-ethylhexyl) -, di- {2 ^ -dimethylhexyl) -, di- (2,3- dimethylhexyl}, di (2,4-dimethylhexyl), di (2,5-dimethylhexyl) *, Di- (3,3-dimethylhexyl) -, di- (3,4-dimethylhexyl) -, di- (2-methyl-3-ethyl-pentyl) -, di- (3-methyl-3-ethylpentyl) -, Di (2,2,3-trimethylpentyl), di (2,2,4-trimethylpentyl), di (233-trimethylpentyl), di- (23,4-trimethylpentyl), di (2 '33' tetramethylbutyl) -amine; corresponding amines with 2 aforementioned, but different radicals, for. B. methylethylamine.

The reaction is carried out at a temperature of 0 to 40, preferably from 15 to 25 ° C, with reduced pressure or overpressure or preferably without pressure, discontinuously or preferably continuously. Water is used, expediently in the form of aqueous formaldehyde solution and / or amine solutions; in addition, water itself forms in the reaction; a total of from 1 to 6, preferably from 3 to 4, moles of water, based on formaldehyde, is considered, hydrocyanic acid is added to the starting mixture before and during the reaction in such an amount that the concentration during the reaction is not more than 0, 1, preferably from 0.01 to 0.1, in particular from 0.05 to 0, l% by weight of hydrocyanic acid, based on the reaction mixture is. The reaction time (in continuous operation residence time) is from 0.1 to 4, preferably 1 to 2, males. Water is preferably used alone as solvent, if appropriate also inert under the reaction conditions, organic solvents. B. in question: aromatic hydrocarbons, eg. Toluene, benzene, ethylbenzene, o-, m-, p-xylene, isopropylbenzene, methylnaphthalene; aliphatisehe or cycloaliphatic hydrocarbons, eg Heptane, pinene, pinane, nonane, o-, m-, p-cymene, gasoline fractions within a boiling point interval from 70 to 190⁰C, cyclohexane, methylcyclohexane, petroleum ether, decalin, hexane, ligroin, 2A4-trimethylpentane, 2,23-trimethylpentane, octane; and corresponding mixtures. The solvent is expediently used in an amount of from 40 to 10 000% by weight, preferably from 50 to 1500% by weight, based on starting materials II.

The reaction may be carried out as follows: A mixture of formaldehyde, water, hydrogen cyanide and starting amine II, optionally together with an organic solvent, is maintained at the reaction temperature during the reaction time. It gives proportions of hydrogen cyanide in the starting mixture and during the reaction in portions or continuously so that the aforementioned hydrocyanic acid concentration is maintained throughout the reaction time. The ongoing measurement of hydrocyanic acid concentration

It is expedient to use J5 via a silver calomel electrode. Then from the reaction mixture of the end product in a conventional manner, for. B. by distillation or extraction with z. As cyclohexane and distillation of the solvent isolated

The N-alkylglycinnitriles obtainable by the process of the invention are valuable starting materials for the preparation of dyes, fungicides, bactericides, textile auxiliaries, auxiliaries in the field of dental cosmetics, gas purification and water repellency. With respect to the use of the aforementioned publications and Ullmann's Encyclopedia of Industrial Chemistry, Volume 8, pages 212 and 213, referenced.

The parts listed in the following examples

so mean parts by weight.

example 1

196 parts of a 30 weight percent aqueous formaldehyde solution, 54 parts of liquid hydrocyanic acid and 214 parts of a 42gewichtsprozentigen dimethylamine solution are slowly added at 18 ° C per hour, wherein during the reaction, the hydrocyanic acid concentration does not exceed 0.1 percent by weight, based on the total mixture. The hydrocyanic acid concentration is on average 0.08 to 0.09 weight percent. Then the reaction mixture is distilled. 330 parts (98% of theory) of N, N-dimethylglycynitrile, bp 63 ° C., πS "1.4107, are obtained per hour.

Example 2

In a stirred tank are analogously to Examples 1 at 18 ° C per hour 400 parts 30gewichtsprozentiger molding

5 6

aldehyde, J 08 parts liquid hydrogen cyanide and 458 parts centrntion below 500 ppm, based on the total

40 weight percent methylamine solution was added, mixed. The hydrocyanic acid concentration is average

wherein in the reaction space the hydrocyanic acid concentration lends at 0.04 weight percent Every hour 966 are obtained

0.1 percent by weight is not exceeded. After parts of a reaction mixture, from which one hourly

a mean residence time of 30 minutes, the 5 by azeotropic dehydration with toluene 270 parts

The reaction mixture passed into a reactor whose (96.4% of theory) of N-methylglycinnitrile ICp₂O

Temperature at 20 ° C Hegt Here sinks the cyanide 65 ° C receives