CS209055B1 - Process for preparing 4-pentenal imines - Google Patents

Abstract

Synthesis of 4-pentenal imines of the general formula I from R1 CH2=CH-CH2-CH2-CH=N-CH< (I), XR2 where R1 and R2 together form a pentamethylene or tetramethylene chain, or R1 and R2 are alkyls with 1 to 2 carbon atoms, consisting in condensing 4-pentenal with primary amines of the formula II H2N-CH R1 R2 (U), where R1 and R2 have the same meaning, at temperatures of -10 to +10 °C, preferably at 0 °C, and after the reaction is complete, a dehydrating agent is added, e.g. sodium or potassium hydroxide, or potassium carbonate.

Description

(54) A method for producing 4-pentenal imines

Synthesis of imines of 4-pentenal of formula I x ^{R 1}

CH ₂ = CH-CH ₂ -CH ₂ -CH = N-CH <(I), ^X R ² where R ¹ and R ² together form a pentamethylene or tetramethylene chain, or R ¹ and R ² are both C ¹ -C 2 alkyl comprising condensing 4-pentenal with primary amines of formula II

H ₂ N-CH

R ¹

R ² (U), wherein R ¹ and R ² have the same meaning, at temperatures of -10 ° C to + 10 ° C, preferably at 0 ° C, after which the water-scavenger, e.g. sodium or potassium hydroxide, is added, or potassium carbonate.

The present invention relates to a process for the preparation of the 4-pentenal imines of formula (I)

R ¹

CH ₂ = CH-CH ₂ -CH ₂ -CH = N-CH <(I), R ² wherein R ¹ and R ² together represent a pentamethylene or tetramethylene chain, or both R ¹ and R ² denote alkyl having 1 to 2 carbon atoms.

The compounds of formula I are all novel and are intermediates for the production of pharmacologically active substances.

The process according to the invention is characterized in that the 4-pentenal of the formula II is used

CH ₂ = CH-CH ₂ -CH ₂ -CH = O (II), * condenses preferably with a stoichiometric amount of the primary amine of formula III

wherein R ¹ and R ² together represent a pentamethylene or tetramethylene chain, or both R ¹ and R ² denote alkyl having 1 to 2 carbon atoms, at -10 to + 10 ° C, preferably at 0 ° C!

After completion of the reaction, a water scavenger, preferably an alkali metal hydroxide such as sodium or potassium hydroxide, or an alkali metal carbonate such as potassium carbonate is added to the mixture.

The following examples illustrate but do not limit the generality of the process of the invention.

Examples

Example 1

To 84.3 g (0.85 mol) of cyclohexylamine (ΙΠ: R ¹ + + R ² = CH ² CH ² CH ² CH ² CH ² ), 71.5 g ( 0.85 mol) of 4-pentenal (Π) over 1.5 h. The reaction mixture is allowed to stand at 0 ° C for 20 minutes. Approximately 10 g of crushed sodium hydroxide is then added and the mixture is stirred occasionally for 15 minutes. The organic phase was separated and dried in a refrigerator over crushed potassium hydroxide overnight. The liquid fraction was separated and distilled in a water pump vacuum. Yielding 104.7 g of N- (4-pentenyliden) cyclohexylamine (I:: ^R + R ² = CH2.CH ₂ .CH ₂ .CH ₂ .CH ₂₎ having a melting point in the range 87 to 88.5 ° C at 1100 Pa. Yield 74.5% of theory.

Example 2

To 11.8 g (0.2 mol) of 2-propylamine (III: R ¹ = R ² = CH 3) was added dropwise with stirring 16.8 g (0.2 mol) of 4-pentenal (II) over 1 h at temperature 0 ° C. The reaction mixture is allowed to stand for 15 minutes at the same temperature and crushed potassium hydroxide is added. At> 0.5 h standing the organic phase is decanted and allowed to stand overnight in the refrigerator over potassium carbonate. After the desiccant is filtered off, the product is distilled. 16.0 g (63.8%) of N- (4-pentenyHden) -2-propylamine (I: R ¹ - R ² = CH 3). The boiling point of the substance is in the range of 131-135 ° C.

Claims (1)

SUBJECT A process for the preparation of 4-pentenal imines of the general formula I / ^R ' CH ₂ = CH-CH ₂ -CH ₂ -CH = N-CH <(I), wherein R ¹ and R ² together represent a pentamethylene or tetramethylene chain, or both R ¹ and R ² denote alkyl having 1 to 2 atoms characterized in that the 4-pentenal of formula (II) CH ₂ = CH-CH ₂ -CH ₂ -CH = O (II), OF THE INVENTION preferably condenses with a stoichiometric amount of the primary amine of formula III A .. ...... ^R \ i> CH-NH _2! (III), rX. ...her· . .. in which both R ¹ and R ² are as defined above, at a temperature of -10 ° C to + 10 ° C, preferably at 0 ° C, wherein at the end of the reaction a water scavenger is added, preferably sodium or potassium hydroxide or potassium carbonate.