IMPROVED METHOD FOR SYNTHESISING PARTIALLY N-HYDROXYETHYLATED TERTIARY 1,6-HEXANEDIAMINES

Abstract

The invention relates to a synthesis method for at least one nitrogen compound belonging to the family of partly N-hydroxyethylated tertiary 1,6-hexanediamines with general formula (I) as follows:

##STR00001##

wherein radicals R.sub.1, R.sub.2, R.sub.3 are each selected indiscriminately among a methyl radical and a hydroxyethyl radical, and at least one radical among R.sub.1, R.sub.2, R.sub.3 is a methyl radical,
comprising at least a first reaction between a first halogen atom-free precursor compound and a second halogen atom-free precursor compound.

The first precursor compound comprises a carbon skeleton consisting of a linear sequence of 6 carbon atoms with the 4 central carbon atoms bonded each to 2 hydrogen atoms and the carbon atoms in alpha and omega position not bonded to a halogen atom.

Claims

1) A synthesis method for at least one nitrogen compound belonging to the family of partly N-hydroxyethylated tertiary 1,6-hexanediamines with general formula (I) as follows: ##STR00034## wherein radicals R.sub.1, R.sub.2, R.sub.3 are each selected indiscriminately among a methyl radical and a hydroxyethyl radical, and at least one radical among R.sub.1, R.sub.2, R.sub.3 is a methyl radical, comprising n reaction steps, n ranging from 1 to 3, and comprising at least a first reaction between a first halogen atom-free precursor compound and a second halogen atom-free precursor compound, said first precursor compound comprising a carbon skeleton consisting of a linear sequence of 6 carbon atoms with the 4 central carbon atoms bonded each to 2 hydrogen atoms and the carbon atoms in alpha and omega position are not bonded to a halogen atom, and wherein none of the n reaction steps comprises a halogenated reactant.

2) A method as claimed in claim 1, for forming at least N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine with formula (I.sub.2) as follows: ##STR00035##

3) A method as claimed in claim 1, wherein the first precursor compound is 1,6-hexanediamine and the second precursor compound 2 PET-3256 is ethylene oxide, said method comprising: a first reaction step between the 1,6-hexanediamine and the ethylene oxide so as to form at least one intermediate compound selected from the list including N-(2-hydroxyethyl)-1,6-hexanediamine, N,N-di(2-hydroxyethyl)-1,6-hexanediamine, N,N-di(2-hydroxyethyl)-1,6-hexanediamine and N,N,N-tri(2-hydroxyethyl)-1,6-hexane-diamine; a second step of methylation of the primary or secondary amine functions of said at least one intermediate compound so as to form at least one compound according to general formula (I).

4) A method as claimed in claim 3, wherein the second methylation step is carried out by reaction between said intermediate compound, formaldehyde and hydrogen in the presence of a hydrogenation catalyst, or by reaction between said intermediate compound, formaldehyde and formic acid according to the Eschweiler-Clarke reaction.

5) A method as claimed in claim 3, wherein the residual 1,6-hexanediamine that has not reacted at the end of the first reaction step is recycled to said first reaction step, after separation by distillation of said 1,6-hexanediamine from said at least one intermediate compound.

6) A method as claimed in claim 3, wherein the molar ratio of ethylene oxide to 1,6-hexanediamine is less than or equal to 3/1, and preferably less than or equal to 2.5/1.

7) A method as claimed in claim 3, further comprising, at the end of the first reaction step, at least one separation step, preferably by distillation, of at least one intermediate compound so as to form a specific compound meeting general formula (I) or a combination of specific compounds meeting general formula (I) at the end of the second methylation step.

8) A method as claimed in claim 2, wherein the first precursor compound is 1,6-hexanediol and the second precursor compound is methylamine, said method comprising: a first step of a condensation reaction between the 1,6-hexanediol and the methylamine, preferably in the presence of hydrogen and of a hydrogenation catalyst so as to form N,N-dimethyl-1,6-hexanediamine; a second reaction step between the N,N-dimethyl-1,6-hexanediamine and the ethylene oxide so as to form N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine.

9) A method as claimed in claim 2, wherein the first precursor compound is adipaldehyde and the second precursor compound is methylamine.

10) A method as claimed in claim 9, comprising the following three reaction steps: a first reaction step of condensation between the adipaldehyde and the methylamine, leading to 1,6-bis(methylimino)-hexane; a second reaction step of reduction of the 1,6-bis(methylimino)-hexane so as to form N,N-dimethyl-1,6-hexanediamine; a third reaction step of ethoxylation of the N,N-dimethyl-1,6-hexanediamine with ethylene oxide so as to form N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine.

11) A method as claimed in claim 9, comprising a step of condensation of the adipaldehyde with the N-methyl-2-aminoethanol in the presence of hydrogen and of a hydrogenation catalyst so as to lead to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine.

12) A method as claimed in claim 2, wherein the first precursor compound is adipic acid or an adipic acid diester.

13) A method as claimed in claim 12, wherein the second precursor compound is N-methyl-2-aminoethanol, said method comprising the following two steps: a first reaction step of condensation of the N-methyl-2-aminoethanol with adipic acid or an adipic acid diester, said adipic acid diester being preferably dimethyl adipate or diethyl adipate, so as to form N,N-dimethyl-N,N-di(2-hydroxyethyl)-adipamide; a second step of reduction of the amide functions of the N,N-dimethyl-N,N-di(2-hydroxyethyl)-adipamide to tertiary amine functions so as to lead to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine.

14) A method as claimed in claim 12, wherein the second precursor compound is methylamine, said method comprising the following three steps: a first step of condensation of the methylamine with adipic acid or an adipic acid diester, said adipic acid diester being preferably dimethyl adipate or diethyl adipate, so as to form N,N-dimethyl-N,N-adipamide; a second step of reduction of the amide functions of the N,N-dimethyl-N,N-adipamide to tertiary amine functions so as to lead to N,N-dimethyl-1,6-hexanediamine, preferably by catalytic hydrogenation or through the action of hydrides, preferably lithium and aluminium hydride; a third step of ethoxylation of the secondary amine functions of the N,N-dimethyl-1,6-hexanediamine with ethylene oxide so as to lead to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine.

15) A method as claimed in claim 1, wherein the first precursor compound is 1,6-hexanediamine and the second precursor compound is formaldehyde, said method comprising: a first step of partial methylation of the 1,6-hexanediamine by reaction with formaldehyde and hydrogen, in the presence of a hydrogen catalyst, so as to form at least one intermediate compound selected from the list comprising N-methyl-1,6-hexanediamine, N,N-dimethyl-1,6-hexanediamine, N,N-dimethyl-1,6-hexane-diamine and N,N,N-trimethyl-1,6-hexanediamine; a second reaction step between ethylene oxide and at least one intermediate compound so as to form at least one compound with general formula (I).

Description

BRIEF DESCRIPTION OF THE FIGURES

[0056] Other features and advantages of the invention will be clear from reading the description hereafter of embodiments given by way of non limitative example, with reference to the accompanying figures wherein:

[0057] FIG. 1 shows a synthesis method for compounds of general formula (I) from 1,6-hexanediamine according to an embodiment of the invention,

[0058] FIG. 2 shows the synthesis of N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine from 1,6-hexanediol according to an embodiment of the invention,

[0059] FIG. 3 shows the synthesis of N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine from adipaldehyde according to an embodiment of the invention (3 steps),

[0060] FIG. 4 shows the synthesis of N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine from adipaldehyde according to another embodiment of the invention (1 step),

[0061] FIG. 5 shows the synthesis of N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine from dimethyl adipate or adipic acid according to an embodiment of the invention (2 steps),

[0062] FIG. 6 shows the synthesis of N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine from dimethyl adipate or adipic acid according to another embodiment of the invention (3 steps), and

[0063] FIG. 7 shows a synthesis method for compounds of general formula (I) from 1,6-hexanediamine according to another embodiment of the invention.

[0064] In the figures, the abbreviation cat stands for catalyst and the arrows represent reaction steps. These are reaction schemes. The illustrations of the synthesis method according to the invention do not comprise all of the components required for implementing it. Only the elements necessary for understanding the invention are shown, the person skilled in the art being able to supplement this representation for implementing the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0065] The present invention relates to the synthesis of partly N-hydroxyethylated tertiary 1,6-hexanediamines with general formula (I) as follows:

##STR00005## [0066] wherein: [0067] radicals R.sub.1, R.sub.2, R.sub.3 are each selected indiscriminately among a methyl radical and a hydroxyethyl radical, and [0068] at least one radical among R.sub.1, R.sub.2, R.sub.3 is a methyl radical.

[0069] Preferably, radicals R.sub.1 and R.sub.3 are methyl radicals and radical R.sub.2 is a hydroxyethyl radical, or radicals R.sub.2 and R.sub.3 are methyl radicals and radical R.sub.1 is a hydroxyethyl radical.

[0070] At least one of the following partly N-hydroxyethylated tertiary 1,6-hexanediamines can be advantageously synthesized according to the invention: [0071] N,N,N-trimethyl-N-(2-hydroxyethyl)-1,6-hexanediamine with formula (I.sub.1) as follows:

##STR00006## [0072] N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine with formula (I.sub.2) as follows:

##STR00007## [0073] N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine with formula (I.sub.3) as follows:

##STR00008## [0074] N-methyl-N,N,N-tri(2-hydroxyethyl)-1,6-hexanediamine with formula (I.sub.4) as follows:

##STR00009##

[0075] Synthesis from 1,6-hexanediamine

[0076] FIG. 1 illustrates the synthesis of at least one compound of general formula (I) from 1,6-hexanediamine, of formula (III).

[0077] The method consists of the succession of two reaction steps from 1,6-hexanediamine.

[0078] The first step consists in reacting the 1,6-hexanediamine with ethylene oxide (formula IV) in suitable amount and conditions so as to obtain either a partly ethoxylated 1,6-hexanediamine such as N-(2-hydroxyethyl)-1,6-hexanediamine (formula II.sub.2) or NN-di(2-hydroxyethyl)-1,6-hexanediamine (formula II.sub.2) or NN-di(2-hydroxyethyl)-1,6-hexanediamine (formula II.sub.3) or NNN-tri(2-hydroxyethyl)-1,6-hexanediamine (formula II.sub.4), or a mixture of these molecules. These partly ethoxylated 1,6-hexanediamines of formula (II.sub.1) to (II.sub.4) are intermediate products in this synthesis mode.

[0079] The reaction conditions are suited in order not to obtain N,N,N,N-tetra(2-hydroxyethyl)-1,6-hexanediamine and to minimize the amount of residual 1,6-hexanediamine. It is therefore advantageous to operate with a molar ratio of ethylene oxide to 1,6-hexanediamine not exceeding 3/1, preferably not exceeding 2.5/1. The selection of the molar ratio between the ethylene oxide and the 1,6-hexanediamine conditions the composition of the products obtained.

[0080] When residual 1,6-hexanediamine is present, it can be removed from the medium by distillation for example and optionally recycled.

[0081] When N,N,N,N-tetra(2-hydroxyethyl)-1,6-hexanediamine is obtained, it can be removed from the medium by distillation for example.

[0082] When a mixture of intermediate compounds is obtained, it can be used as it is to carry out the second step or it can be subjected to separation, by distillation for example, in order to obtain one of the compounds of general formula (I) or a combination of these compounds (formulas I.sub.2 to I.sub.4) at the end of the second step.

[0083] The second step consists in the methylation of the primary or secondary amine functions of the intermediate compounds (of formulas II.sub.2 to II.sub.4) obtained in the first step in order to lead to N,N,N-dimethyl-N-(2-hydroxyethyl)-1,6-hexanediamine (formula I.sub.1) and/or N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine (formula I.sub.2) and/or N,N-dimethyl-NN-di(2-hydroxyethyl)-1,6-hexanediamine (formula I.sub.3) and/or N-methyl-NNN-tri(2-hydroxyethyl)-1,6-hexanediamine (formula I.sub.4).

[0084] Methylation of the amine functions can be achieved using any means known to the person skilled in the art, notably by reaction of formaldehyde (HCHO) and hydrogen (H.sub.2) in the presence of a suitable catalyst (as shown in FIG. 1) or for example by reaction of formaldehyde and formic acid according to the reaction known as Eschweiler-Clarke reaction.

[0085] According to an alternative synthesis pathway from 1,6-hexanediamine, the ethoxylation and methylation steps can be reversed in relation to the pathway described above and illustrated in FIG. 1. In this case, a first step of partial methylation of the 1,6-hexanediamine, by reaction with formaldehyde and hydrogen in the presence of a hydrogenation catalyst, leads to N-methyl-1,6-hexanediamine (formula (II.sub.4)) and/or to N,N-dimethyl-1,6-hexanediamine (formula (II.sub.3)) and/or to N,N-dimethyl-1,6-hexanediamine (formula (II.sub.2)) and/or to N,N,N-trimethyl-1,6-hexanediamine (formula (II.sub.1)). Then, in a second step, the primary and secondary amine functions are ethoxylated by reaction with ethylene oxide (formula (IV)). This variant of this first synthesis method is illustrated in FIG. 7.

[0086] Synthesis from 1,6-hexanediol

[0087] A compound of general formula (I) can be synthesized from 1,6-hexanediol (formula (V)).

[0088] FIG. 2 illustrates the synthesis of an example of a compound with general formula (I), N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2), from 1,6-hexanediol of formula (V).

[0089] The synthesis consists of the succession of two reaction steps: the condensation of 1,6-hexanediol with methylamine (MeNH.sub.2) generally used in excess in the presence of hydrogen and of a suitable catalyst for leading to N,N-dimethyl-1,6-hexanediamine (formula (VI)) which is subsequently converted to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine (formula (I.sub.2)) through an ethoxylation reaction with ethylene oxide (formula (IV)).

[0090] Synthesis from Adipaldehyde

[0091] A compound of general formula (I) can be synthesized from adipaldehyde.

Synthesis in 3 Reaction Steps

[0092] A compound of general formula (I) can be synthesized in three reaction steps from adipaldehyde (formula (VII)).

[0093] FIG. 3 illustrates the synthesis of an example of a compound with general formula (I), N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2), from adipaldehyde of formula (VII), according to a synthesis method in three reaction steps.

[0094] The synthesis consists of the succession of three reaction steps.

[0095] The first step consists in a condensation reaction of the adipaldehyde (formula (VII)) with methylamine (MeNH.sub.2) leading to 1,6-bis(methylimino)-hexane (formula (VIII)).

[0096] A second reaction step consists in the reduction of the 1,6-bis(methylimino)-hexane (formula (VIII)) to N,N-dimethyl-1,6-hexanediamine (formula (VI)).

[0097] A third reaction step consists in the ethoxylation of the N,N-dimethyl-1,6-hexanediamine (formula (VI)) with ethylene oxide (formula (IV)) so as to form N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine (formula (I.sub.2)).

Synthesis in 1 Reaction Step

[0098] A compound of general formula (I) can be synthesized in a single reaction step from adipaldehyde (formula (VII)).

[0099] FIG. 4 illustrates the synthesis of an example of a compound with general formula (I), N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2), from adipaldehyde (formula (VII)), according to a synthesis method in a single reaction step.

[0100] The synthesis consists in the condensation of the adipaldehyde (formula (VII)) with N-methyl-2-aminoethanol (formula (IX)) in the presence of hydrogen and of a suitable hydrogenation catalyst leading to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexane-diamine (formula (I.sub.2)).

[0101] This transformation, also referred to as reductive amination, results from the succession of two reactions which are the condensation of a secondary amine with an aldehyde leading to an amine, then the hydrogenation thereof to a tertiary amine.

[0102] Synthesis from Adipic Acid or from an Adipic Acid Diester

[0103] A compound of general formula (I) can be synthesized from adipic acid or from an adipic acid diester.

Synthesis in 2 Reaction Steps

[0104] A compound of general formula (I) can be synthesized in two reaction steps from adipic acid (formula (XI)) or from an adipic acid diester such as dimethyl adipate (formula X)).

[0105] FIG. 5 illustrates the synthesis of an example of a compound with general formula (I), N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2), from adipic acid (formula (XI)) or from an adipic acid diester, such as dimethyl adipate (formula (x)), according to a synthesis method in two reaction steps.

[0106] A first step consists in the condensation reaction of N-methyl-2-aminoethanol (formula (IX)) with either adipic acid (formula (XI)) or an adipic acid diester such as, by way of non limitative example, dimethyl adipate (formula (x)) or diethyl adipate. The condensation product obtained is a diamide, N,N-dimethyl-N,N-di(2-hydroxyethyl)-adipamide (formula (XII)).

[0107] The second step consists in the reduction of the amide functions of the N,N-dimethyl-N,N-di(2-hydroxyethyl)-adipamide (formula (XII)) to tertiary amine functions leading to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine (formula (I.sub.2)).

[0108] This reduction can be carried out by any known means such as reduction by catalytic hydrogenation or the action of hydrides such as lithium and aluminium hydride.

Synthesis in 3 Reaction Steps

[0109] A compound of general formula (I) can be synthesized in three reaction steps from adipic acid (formula (XI)) or from an adipic acid diester such as dimethyl adipate (formula X)).

[0110] FIG. 6 illustrates the synthesis of an example of a compound with general formula (I), N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2), from adipic acid (formula (XI)) or from an adipic acid diester, such as dimethyl adipate (formula (x)), according to a synthesis method in three reaction steps.

[0111] A first step consists in the condensation of methylamine (MeNH.sub.2) with either adipic acid (formula (XI)) or an adipic acid diester such as, by way of non limitative example, dimethyl adipate (formula (x)) or diethyl adipate. The condensation product obtained is a diamide: N,N-dimethyl-N,N-adipamide of formula (XIII).

[0112] A second step consists in the reduction of the amide functions of the N,N-dimethyl-N,N-adipamide of formula (XIII) to tertiary amine functions leading to N,N-dimethyl-1,6-hexanediamine (formula (VI)). This reduction can be carried out by any known means such as reduction by catalytic hydrogenation or the action of hydrides such as lithium and aluminium hydride.

[0113] A third step consists in ethoxylating the secondary amine functions of the N,N-dimethyl-1,6-hexanediamine (formula (VI)) with ethylene oxide (formula (IV)) leading to N,N-dimethyl-N,N-di(2-hydroxyethyl)-1,6-hexanediamine of formula (I.sub.2).

APPENDIX: LIST OF THE COMPOUND NAMES AND THEIR FORMULAS APPEARING IN THE FIGURES

[0114]

TABLE-US-00001 Ref. Name Formula (I.sub.1) N,N,N-trimethyl-N-(2-hydroxyethyl)- 1,6-hexanediamine of formula (I.sub.1) as follows [00010] (I.sub.2) N,N-dimethyl-N,N-(2-hydroxyethyl)- 1,6-hexanediamine [00011] (I.sub.3) N,N-dimethyl-N,N-di(2-hydroxyethyl)- 1,6-hexanediamine [00012] (I.sub.4) N-methyl-N,N,N-tri(2-hydroxyethyl)- 1,6-hexanediamine [00013] (II.sub.1) N-(2-hydroxyethyl)-1,6- hexanediamine [00014] (II.sub.2) N-N-di(2-hydroxyethyl)-1,6- hexanediamine [00015] (II.sub.3) N,N,-di(2-hydroxyethyl)-1,6- hexanediamine [00016] (II.sub.4) N-N-N-tri(2-hydroxyethyl)-1,6- hexanediamine [00017] (III) 1,6-Hexanediamine [00018] (IV) Ethylene oxide [00019] (V) 1,6-Hexanediol [00020] (VI) N,N-dimethyl-1,6-hexanediamine [00021] (VII) Adipaldehyde [00022] (VIII) 1,6-bis(methylimino)-hexane [00023] (IX) N-methyl-2-aminoethanol [00024] (X) Dimethyl adipate [00025] (XI) Adipic acid [00026] (XII) N,N-dimethyl-N,N-di(2- hydroxyethyl)-adipamine [00027] (XIII) N,N-dimethyl-N,N-adipamide [00028] (II.sub.1) N,N,N-trimethyl-1,6-hexanediamine [00029] (II.sub.2) N,N-dimethyl-1,6-hexanediamine [00030] (II.sub.3) N,N-dimethyl-1,6-hexanediamine [00031] (II.sub.4) N-methyl-1,6-hexanediamine [00032] [00033]