WO2022133851A1

WO2022133851A1 - Processes for producing amine oxides

Info

Publication number: WO2022133851A1
Application number: PCT/CN2020/138827
Authority: WO
Inventors: Wenjuan ZHOU; Stephane Streiff; Alexander Lerch
Original assignee: Rhodia Operations
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2022-06-30

Abstract

The method relates to a tertiary amine oxide by reacting an aliphatic tertiary amine with oxygen or oxygen-containing gas, wherein the process is carried out in the presence of aldehydes with or without ketones. It is described that high yield and selectivity and discarded metal catalyst can be realized by the amine oxidation of gaseous oxidizer. The process steps are relatively simple, which improves economic efficiency.

Description

[Title established by the ISA under Rule 37.2] PROCESSES FOR PRODUCING AMINE OXIDES

TECHNICAL FIELD

The invention relates to a process for oxidation of fatty dimethyl amine to synthesize fatty-dimethyl amine oxide. The oxidation is carried out with oxygen or oxygen-containing gas in the presence of aldehydes with or without ketones.

BACKGROUND

The following discussion of the prior art is provided to place the invention in an appropriate technical context and enable the advantages of it to be more fully understood. It should be appreciated, however, that any discussion of the prior art throughout the specification should not be considered as an express or implied admission that such prior art is widely known or forms part of common general knowledge in the field.

Amine oxides are amphoteric surfactants and commonly used in many commercial products, such as laundry detergents, fabric softeners, and shampoos, served as stabilizers, thickeners, emollients, emulsifiers, and conditioners with active concentrations.

Fatty tertiary amine oxides are industrially prepared by oxidation of tertiary amines with hydrogen peroxide in the presence of metal catalysts, such as RuCl ₃ or Fe (acac) ₂. The general cycle time is between 6-8 hours, even longer around 10-24 hours for hydrogen peroxide as oxidant, when the yield reaches above 85%. Many methods above mentioned need metal catalyst and/or produce undesired side reactions and/or high metal salts or catalysts residue. And, using hydrogen peroxide as oxidant requires for a relative higher temperature. However, hydrogen peroxide is unstable, easy to decompose, and has high requirements for transportation and storage. Higher temperatures, such as equal to or above 80 ℃, are not favorable because of the apparent tendency of decomposition of both hydrogen peroxide and the amine oxide at such high temperatures.

Therefore, there is still a need in the industry and it would be desirable to find alternative, recyclable and mild conditions, salt free waste and metal free process that are effective with shorter reaction time than that of conventional hydrogen peroxide reaction system reaction system. Such process steps are relatively simple, which improves economic efficiency.

SUMMARY OF THE INVENTION

The present invention concerns a process for producing an amine oxide by reacting an aliphatic tertiary amine with oxygen or oxygen-containing gas in the presence of aldehydes with or without ketones under the temperature from 40 to 75℃.

We have surprisingly found that such process using oxygen or oxygen-containing gas in the presence of aldehydes with or without ketones needs shorter reaction time and lower reaction temperature. It also appears that the process of the present invention permits to obtain very good final product, higher yield, and lower cost and environmentally friendly outcomes in comparison with other N-oxides preparation in the state of the art.

Other characteristics, details and advantages of the invention will emerge even more fully upon reading the description which follows.

DEFINITIONS

For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

The articles “a” , “an” and “the” are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

The term “and/or” includes the meanings “and” , “or” and also all the other possible combinations of the elements connected to this term.

It should be noted that in specifying any range of concentration, weight ratio or amount, any particular upper concentration, weight ratio or amount can be associated with any particular lower concentration, weight ratio or amount, respectively.

The terms “comprise” and “comprising” are used in the inclusive, open sense, meaning that additional elements may be included. Throughout this specification, unless the context requires otherwise the word “comprise” , and variations, such as “comprises” and “comprising” , will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

The term “including” is used to mean “including but not limited to” . “Including” and “including but not limited to” are used interchangeably.

The term “consisting of” means the embodiment necessarily includes the listed components only and no other unlisted components are present.

Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a temperature range of 40℃ to 65℃ should be interpreted to include not only the explicitly recited limits of 40℃ to 65℃, but also to include sub-ranges, such as 40℃ to 55℃, 45℃ to 55℃, 40℃ to 60℃, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 40.3℃, 50.5℃, and 54.9 ℃, for example.

The term “between” should be understood as being inclusive of the limits.

It is specified that, in the continuation of the description, unless otherwise indicated, the values at the limits are included in the ranges of values which are given. It should be noted that in specifying any range of concentration, any particular upper concentration can be associated with any particular lower concentration.

As used herein, the terminology " (C _n-C _m) " in reference to an organic group, wherein n and m are each integers, indicates that the group may contain from n carbon atoms to m carbon atoms per group.

DETAILS OF THE INVENTION

Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively and any and all combinations of any or more of such steps or features.

A preferred embodiment of this invention is a process for oxidizing an aliphatic tertiary amine with oxygen or oxygen-containing gas to form a tert-amine oxide, said process comprising contacting said aliphatic tertiary amine with oxygen or oxygen-containing gas in the presence of aldehydes with or without ketones. Without wishing to be bounded by any theory, the reaction time is reduced and free of metal salts or catalysts.

The aliphatic tertiary amines in the process according to the present invention may have the general formula (I) :

Wherein R ₁, R ₂ and R ₃, independently from each other, represent a C ₁-C ₃₀ straight, branched or cyclic alkyl, alkenyl, alkynyl group and preferably represent a C ₁-C ₂₀ straight alkyl group. Preferably, the total amount of carbon atoms in R ₁, R ₂ and R ₃ is 10 to 90, more preferably 10 to 60, more preferably 10 to 50, and most preferably 10 to 40.

Preferred aliphatic tertiary amines are the amines of formula I wherein R ₁ is a straight alkyl group having about 1-20 carbon atoms, R ₂ is a alkyl group having 1-10 carbon atoms, such as methyl, ethyl or octyl, or even extended to 1-20 carbon atoms, and R ₃ is methyl or ethyl.

R ₁, R ₂ and R ₃ can be different.

In some embodiments, R ₁ and R ₂, independently from each other, are C1-C20 straight alkyl group. R ₃ is a methyl or ethyl. Representative examples of these are n-octyldimethylamine, n-decyldiethylamine, n-dodecyldiethylamine, n-dodecyldimethylamine, n-tridecyldimethylamine, n-dimethytetradecyllamine, n-cetyldimethylamine, n-octadecyldimethylamine, n-eicosyl dimethylamine, n-octyl n-dodecylmethylamine, n-decyl n-eicosylethylamine, and the like.

In some embodiments, R ₁, R ₂ and R ₃, independently from each other, are C1-C10 straight alkyl group. Representative example is n-octadecyl di- (n-butyl) amine.

In some embodiments, R ₁, R ₂ and R ₃, independently from each other, are C10-C20 straight alkyl group. Representative example is n-eicosyl di- (n-decyl) amine.

R ₁, R ₂ and R ₃ can be same.

Representative examples of these are trimethylamine, triethylamine, trimethylamine, tri-n-pentylamine, tri-n-dodecylamine, trieicosylamine.

Representative examples of aliphatic tertiary amine include but are not limited to, n-octadecyl di- (n-butyl) amine, n-eicosyl di- (n-decyl) amine, N-tridecyl-dodecylmethylamine, docosyldioctylamine, triacontylbutylamine and the like.

In one embodiment, a preferred aliphatic tertiary amine is n-dodecyldimethylamine.

In one embodiment, a preferred aliphatic tertiary amine is n-tridecyldimethylamine.

In one embodiment, a preferred aliphatic tertiary amine is n-tetradecyldimethylamine.

In one embodiment, a preferred aliphatic tertiary amine is n-cetyldimethylamine.

In one embodiment, a preferred aliphatic tertiary amine is n-octadecyldimethylamine.

In one embodiment, a preferred aliphatic tertiary amine is N, N-dimethyldodecylamine (MDA) .

According to the present invention, with oxygen or oxygen-containing gas (such as notably air, O ₂-N ₂ or O ₂-Ar) the oxidation is carried out.

The O ₂ pressure is generally comprised between 1 and 5 bar, preferably 1 to 3 bar.

The mode of adding the reactants is variable. The amine can be added to the solvent with insert of oxygen or oxygen-containing gas. Or the solvent can be added to the amine with insert of oxygen or oxygen-containing gas. It was proposed to gradually insert oxygen or oxygen-containing gas, under agitation of the amine and the solvents at 40 to 75℃, continuing the agitation and maintaining the temperature of the mixture within this range until substantially complete conversion to the oxide was effected.

The reaction is conducted at a temperature in a mild condition to cause the desired reaction to proceed but not so high as to cause excessive decomposition of the products. A useful temperature range is 40 ℃ to 75℃. A preferred range is 40℃ to 70℃ with a more preferred range of 40℃ to 65 ℃, even more preferred range of 40℃ to 60℃. The reaction should be conducted for a time sufficient to achieve the desired degree of completion of the reaction. A feature of the present process is that it achieves a higher reaction rate with reaction time reduced apparently than that achieved under the same conditions but with NaHCO ₃ or metal complex as catalyst. Good results can be obtained in 1 to 5 hours with the preferable range being between 1.5 to 4.5 hours, more preferable being 2 to 4.5 hours and even preferably being 2 to 4 hours.

It is preferred the aldehydes can be selected from aliphatic aldehydes or the mixture thereof, such as isobutyraldehyde. A preferred amount of tertiary amine to aldehydes is about 1: 1 to 5: 1 moles. A more preferred amount of tertiary amine to aldehydes is 1: 1 to 4: 1 moles, more preferably 1: 1 to 3: 1.

While the reaction can take place further in the presence of ketones, wherein the ketones can be selected from trifluoroacetophenone or its derivatives, such as substituted by halogen on the ring or side chain. Apreferred amount of aldehydes to ketones is about 0.5: 1 to 2: 1 moles. A more preferred amount of aldehydes to ketones is 0.5: 1 to 1.5: 1 moles.

The reaction can take place with a solvent, it is preferred that a solvent for the reactants be employed. Illustrative solvents are such as water, CH ₃CN, CH ₂CH ₂Cl ₂. It is preferred the reaction does not contain alcohols as solvents, such as methanol, ethanol, and the like. The solvent is conveniently employed in an amount to just dissolve all the reactants, but larger or smaller amounts of solvent can be used if desired.

No theory is bounded to the reaction mechanism. It is to be understood that oxygen reacts with aldehydes, such as isobutyraldehyde, to form isobutyr-peroxyacid, then the peroxide reacts with tertiary amine, such as N, N-dimethyldodecylamine (MDA) , to form amine oxide and isobutyric acid. The reaction takes much faster than that of H ₂O ₂ as oxidant under similar reaction temperature.

While ketones is applied to the reaction, it is to be understood that oxygen reacts with aldehydes, such as isobutyraldehyde, to form isobutyr-peroxyacid, then the peroxide react with ketones, such as trifluoroacetophenone, to form perhydrate, which reacts with tertiary amine, such as N, N-dimethyldodecylamine (MDA) , to form amine oxide and isobutyric acid.

Since no inorganic unfriendly environment salts employed or produced in the reaction, another benefit of the present process is that it provides the amine oxides with high purity and environmental friendly thereby giving a more marketable product.

EXPERIMENTAL PART

The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Other examples are also possible which are within the scope of the present disclosure.

Reference products:

N, N-dimethyldodecylamine (Fentamine DMA 1214L) : > 97.1 wt. %, CAS: 112-18-5, Solvay;

Isobutyraldehyde: ≥ 98 %, CAS: 78-84-2, J&K;

2, 2, 2-Trifluoroacetophenone: 98 %, CAS: 434-45-7, J&K;

O ₂: purity ≥99 %, CAS: 132259-10-0, air liquid.

Analytical method

NMR Spectroscopy

The product was analyzed by NMR on a Bruker Avance III 300 MHz spectrometer operating at 300 MHz resonance frequencies, equipped with a BBO probe.

Example 1 Preparation of N, N-dimethyldodecylamine amine oxide (MDAO)

1.1 CH ₃CN used as solvent

N, N-dimethyldodecylamine (Fentamine DMA 1214L) (MDA, 0.22 g) and isobutyraldehyde (0.21 g) and CH ₃CN (2.06 g) were sequentially added into a high-pressure batch reactor. The reactor was pressurized with oxygen to a pressure of 2 bar and then sealed. The mixture was heated to the reaction temperature of 60℃ under a magnetic stirring (400-600 rpm) for 4 h. The end solution were taken from reactor to quantify the yield of N, N-dimethyldodecylamine amine oxide (MDAO) by 1H NMR. The results are shown in Table 1.

1.2 CH ₂CH ₂Cl ₂ used as solvent

Reaction conditions in §1.2 are similar as §1.1 of the embodiment, except for the solvent here used as CH ₂CH ₂Cl ₂ and reaction temperature of 70 ℃.

1.3 CH ₃OH used as solvent

Reaction conditions in §1.3 are similar as §1.1 of the embodiment, except for the solvent here used as CH ₃OH and reaction temperature of 70 ℃.

1.4 CH ₃CH ₂OH used as solvent

Reaction conditions in§1.4 are similar as §1.1 of the embodiment, except for the solvent here used as CH ₃CH ₂OH and reaction temperature of 70 ℃.

Table 1 Effect of different solvent

Solvents	Temperature (℃)	MDAO yield %
CH ₃CN	60	100
CH ₂CH ₂Cl ₂	70	100
CH ₃CN	30	28
CH ₂CH ₂Cl ₂	30	20
CH ₃OH	70	0
CH ₃CH ₂OH	70	0

Reaction condition: MDA: Isobutyraldehyde= 1: 3 (molar ratio) ; O ₂: 2 bar; 4 h.

Table 2 Reaction time to reach 100%yield using CH ₃CN or CH ₂CH ₂Cl ₂ as solvent

Reaction condition: 0.22g MDA, 2.06 g solvent, 50 ℃.

Results indicate that reaction with CH ₃CN or CH ₂CH ₂Cl ₂ as the solvent can achieve excellent yield of amine oxides within 4 hours at low temperature, which is much efficient than that of H ₂O ₂ as oxidant (more than 6 hours) .

Example 2 Preparation of N, N-dimethyldodecylamine amine oxide in presence of isobutyraldehyde and trifluoroacetophenone

N, N-dimethyldodecylamine (Fentamine DMA 1214L) (MDA, 0.22 g) and isobutyraldehyde (shown as Table 3) , trifluoroacetophenone (shown as Table 3) and CH ₃CN (2.06 g) were sequentially added into a high-pressure batch reactor. The reactor was pressurized with oxygen to the pressure (shown as Table 3) and then sealed. The mixture was heated to the reaction temperature of 70 ℃ under a magnetic stirring (400-600 rpm) for 4 h. The end solution were taken from reactor to quantify the yield of N, N-dimethyldodecylamine amine oxide (MDAO) by 1H NMR. The results are shown in Table 3.

Table 3 Effect of isobutyraldehyde and trifluoroacetophenone

Reaction condition: 0.22gMDA, 2.06 g CH ₃CN, 70 ℃, 4h.

It can be seen that the present invention can obtain the yield of the tertiary amine oxide is equal to or higher than 99%. The final product is free of salt residues.

Claims

A process for producing an amine oxide by reacting an aliphatic tertiary amine with oxygen in the presence of aldehydes under the temperature from 40-75℃, preferably 40℃ to 70℃.
The process according to claim 1, wherein reacting an aliphatic tertiary amine with oxygen is carried out for 1 to 5 hours, preferably 1.5 to 4.5 hours, more preferably 2 to 4.5 hours, even more preferably 2 to 4 hours.
The process according to claim 1 or 2, wherein O ₂ pressure is comprised between 1 and 5 bar, preferably 1 to 3 bar.
The process according to any one of claims 1 to 3, wherein the aliphatic tertiary amine has the general formula (I) :

wherein R ₁, R ₂ and R ₃, independently from each other, represent a C ₁-C ₃₀ straight, branched or cyclic alkyl, alkenyl, alkynyl group and preferably represent a C ₁-C ₂₀ straight alkyl group.
The process according to claim 4, wherein R ₁ is a primary alkyl having about 1-20 carbon atoms, R ₂ is a primary alkyl having either 1-2 carbon atoms or having 1-20 carbon atoms and R ₃ is methyl or ethyl.
The process according to claim 4, wherein the aliphatic tertiary amine is selected from the group comprising n-dodecyldimethylamine, n-tetradecyldimethylamine, n-cetyldimethylamine, n-octadecyldimethylamine or N, N-dimethyldodecylamine.
The process according to any one of claims 1 to 6, wherein the mole ratio of tertiary amines to aldehydes is 1: 1 to 5: 1, preferably 1: 1 to 4: 1, even more preferably 1: 1 to 3: 1.
The process according to claim 1, wherein it is in the presence of ketones.
The process according to claim 7, wherein the ketone can be selected from the trifluoroacetophenone or its derivatives.
The process according to claim 1, wherein the aldehydes can be isobutyraldehyde.
The process according to any one of claims 8 to 10, wherein the mole ratio of aldehydes to ketones is 0.5: 1 to 2: 1, preferably 0.5: 1 to 1.5: 1.
The process according to claim 1, wherein producing an amine oxide further in the presence of at least one solvent, such as CH ₃CN or CH ₂CH ₂Cl ₂.
The process according to any one of claims 1 to 12, wherein the yield of the tertiary amine oxide is equal to or higher than 99%.