DE1593212C3 - Process for the preparation of maleamic acid derivatives - Google Patents

Description

H ₂ N- (CH ₂ ) ,, - N

wherein i, R ₁ and R ₂ have the abovementioned meanings, in the presence, of a solvent, which is characterized in that the solvent used is ethyl acetate or tert-butyl alcohol at temperatures up to and including 5O ⁰ C.

The preparation of such maleamic acid derivatives is already known from US Pat. No. 2,821,521 known; in the condensation described there, however, aromatic hydrocarbons are used as solvents, such as benzene, toluene, xylene, etc. are used. However, these solvents show different ones Disadvantage. For example, when Ν, Ν-diethylaminopropylamine is used, the corresponding Maleamic acid derivative obtained in the form of a colored sticky paste which crystallizes only with difficulty. The purification of the maleamic acid derivatives obtained in this way is therefore very laborious. This disadvantage has a particularly unpleasant effect when the maleamic acid derivatives directly for the synthesis of other products, such as. B. of asparagine derivatives are to be used.

It has now been found that when ethyl acetate or tert-butyl alcohol is used as the solvent, the maleamic acid derivatives precipitate in crystallized form after the reaction has ended. The reaction at temperatures up to and including 50 ^° C., preferably below 30 ^° C., is carried out. The total concentration of the reactants is advantageously 30 to 40 percent by weight. When using tert-butyl alcohol as solvent, a reaction temperature of 50 ° C. is advantageously maintained.

As can be seen from the table, compliance with the optimal reaction conditions when using the solvents mentioned depends on _{the nature of the radicals R 1} and R _2.

Tabel

CH-CONH - (CH ₂ ) - N
CH-COOH R ₂ Solution
middle Tem
temperature total
concentrate
tration of
Reaction
Attendees yield Aminst
in milliequ nitrogen
ivalcntcn / g acid
in milliequ salary
ivalcnten / g in g / 100 g calculated found calculated found R ₁ = R ₂ = C ₂ H ₅ , η = 3 ethyl
acetate O to
5 ⁰ C 38.8% 100% 4.38 4.39 4.38 4.41 tert.-
Butyl
alcohol 50 ° C 33.4% 98% 5.00 4.87 5.00 5.13 R ₁ = R ₂ ⁼ C ₂ H ₅ , /! = 2 tert.-
Butyl
alcohol 50 ⁰ C 35% 89% 4.67 4.59 4.67 4.49

The process according to the invention is explained in more detail below with the aid of further examples.

example 1

To a solution of 390 g (3 mol) of N, N-diethylaminopropylamine in 600 cm ^{3 of} ethyl acetate, 297 g of maleic anhydride, dissolved in 600 cm ^{3 of} ethyl acetate, are added with stirring and with the aid of a funnel. During the addition of the maleic anhydride, the temperature is kept between 0 and 5 ° C. The duration of this process is 2 ¹ I ₂ hours. A few minutes before the end of the entry, the Ν, Ν-diethylaminopropylmaleamic acid begins to precipitate, which is separated off by filtration after the reaction mixture has stood for several hours at room temperature. After washing with ethyl acetate, separating and drying, a white powder is obtained in 100% yield.

Example 2

204 g (2 mol) Ν, Ν-dimethylaminopropylamine are dissolved in 800 g tert-butyl alcohol and the solution at 50 ⁰ C heated. 198 g of powdered maleic anhydride are then introduced at 50 ^° C. over the course of one hour, with stirring. After the reaction mixture has stood for a few hours, the N, N-dimethylaminopropylmaleamic acid formed precipitates. After filtering off, washing with acetone and drying, a white powder is obtained in a yield of 98% (melting point = 56 to 59 ° C.).

Claims (1)

Claim: Process for the preparation of maleamic acid derivatives the formula CH - CO - NH - (CH ₂ ) ,, - N CH-COOH R, where R ₁ and R _{2 are} identical or different alkyl radicals with up to 4 carbon atoms or, taken together, also form the morpholino or piperidino radical and η denotes an integer from 2 to 5, by condensation of maleic anhydride with an alkylenediamine of the formula H ₂ N- (CH ₂ ) ,, - N 25th wherein n, R ₁ and R ₂ have the abovementioned meaning, in the presence of a solvent, characterized in that the solvent used is ethyl acetate or tert-butyl alcohol in compliance with temperatures up to 50 ⁰ C. 35 The invention relates to a process for the preparation of maleamic acid derivatives of the formula R, 40 CH - CO - NH - (CH ₂ ) "- N CH-COOH R ₂ wherein R ₁ and R _{2 are} identical or different alkyl radicals with up to 4 C atoms or together 45 taken also form the morpholino or piperidino radical and η denotes an integer from 2 to 5, by condensation of maleic anhydride with an alkylenediamine of the formula