DE2557456A1 - PROCESS FOR THE PRODUCTION OF AMINOXIDES - Google Patents

Description

Patent attorneys

Dipl. Incr. iTuns-rTii'-rn Müller
Dr. rar. r. U. Tlw>: \. J. ^ Uereudt

D6 Munich oQ Lu ^ iis-Gichn-SlraSe 38

Albright & Wilson Limited,

Oldbury, Warley, West Midlands, UK

Process for the preparation of amine oxides

The invention relates to a process for the preparation of amine oxides.

It is known to react tertiary amines with peroxy compounds, such as hydrogen peroxide, in the presence of water, dilute solutions of the corresponding amine oxides being obtained. The amine oxides obtained are used as surfactants and bacteriostats in shampoos and laundry detergents. The procedure is for example in "Journal of the American Oil Chemists Society", Vol. 40, (1963}, pages 268-271 and 628-631, U.S. Patent 3,316,236 and GB-PSS 992,860; 1,084,739 and 1,087.

The reaction is very easy if there is a sufficient amount of water. However, if the concentration of the mixture obtained at the end exceeds about 30% by weight of amine oxide, a highly viscous phase is formed, as a result of which the mixture forms a hard-to-work gel as the concentration increases. To counter this phenomenon

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To work it was emphasized according to the prior art that one should work with dilute solutions. However, there are in storage and transport solutions that not less than 70 wt -.% Containing water, significant economic disadvantages. The separation of amine oxides from aqueous solutions is difficult and expensive, the production of concentrated solutions was considered impossible or impracticable, since the increase in viscosity with increasing concentration was assumed to be continuous when the concentration rises to 100% by weight.

It has now surprisingly been found that when the concentration of the amine oxide increases above about 60% by weight is left, the viscosity passes through a maximum and a liquid phase is formed, after which the viscosity falls back to a minimum at about 75% by weight before increasing again with further increase in concentration. It has surprisingly been found that within the concentration range from 70 to 80% by weight aqueous solutions of amine oxides are sufficiently liquid to be poured and allow such solutions in economical feasible way to make them, even if these are too viscous to be at any other concentration above 30% by weight to be produced.

According to the invention, therefore, a process for the preparation of amine oxides is provided, which is characterized in that that you have a tertiary amine, a peroxidizing agent and sufficient water to make the product at a concentration above 60% by weight, based on the mixture, in a pourable State to keep mixed together.

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The reaction conditions according to the invention are in essentially the same as in the publications of the prior art mentioned at the beginning is the case, with the exception of the reduced proportion of water

The reaction is generally applicable to the oxidation of any aqueous solution of an oxidizable amine * whose oxides are pourable at a viscosity minimum above 60% by weight, including alkyl, alkenyl, Aralkyl, polyoxyalkylene, alkyl polyoxyalkylene amines and heterocyclic tertiary amines. The invention is particularly useful for the oxidation of amines of the general formula

R ^f

R-N

• ... ι

in which R ¹ , R ¹¹ each have lower alkyl groups (for example those with 1 to 4 carbon atoms), in particular methyl groups, and R is a higher alkyl group (for example those with 8 to 20 carbon atoms), in particular an alkyl group with 12 to 16 carbon atoms Represents atoms or an alkyl-polyoxyalkylene group, the alkyl group having, for example, 8 to 20 carbon atoms and this group having, for example, 1 to 20 oxyalkylene units (eg oxyethylene units). Any of the oxidizable tertiary amines published in the prior art mentioned at the beginning can be used, provided that the aqueous solutions of the oxides produced have a pourable phase at concentrations above 60% by weight. It is also possible to use mixtures of tertiary amines.

The peroxidizing agent is preferably an aqueous solution of hydrogen peroxide, for example a 50% aqueous solution

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Solution. Other peroxidizing agents can be used as long as the by-products formed in the oxidation do not increase the viscosity of the solution to such an extent that the formation of a pourable phase is avoided. For example, mixtures of hydrogen peroxide with peracetic acid, an aqueous ozone solution or perbenzoic acid can be used will.

The amount of water used will depend on the particular amine oxide being made. In general, it is preferred an amount of water corresponding to (m + 5) to (m - 5)% by weight, based on the finished mixture, particularly preferably m% by weight, to be used, where m is the percentage concentration of the water in% by weight, based on the mixture, at the minimum that occurs when the viscosity is plotted graphically against concentration, this minimum being below 40% by weight of water. The value of m varies slightly depending on the tertiary amine selected and can be checked by a usual routine test in each specific case. The value is generally between concentration / from 10 to 40 wt. #, E.g. 20 to 30% by weight. Preferably, the total amount of water used is calculated so that you get as close as possible to the Value m wt .-% water comes, as can be done with the finished mixture. The water can go along with however, it is preferred added with the peroxidizing agent.

According to a typical embodiment, the peroxidizing agent is added to the amine slowly and preferably with stirring. The mixture can be easily heated, as is known in the art, all other conditions of the temperature, the reaction time and the mixing conditions essentially according to the

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mentioned prior art can be selected.

According to one embodiment of the invention, this consists in the value of m as defined above for a to determine certain tertiary amine oxide and a peroxidizing agent, such as preferably an aqueous one Solution of hydrogen peroxide to be added to the corresponding tertiary amine in the presence of sufficient water, that a total concentration of (m + 5) to (m - 5) wt .-% (based on the weight of the mixture) Water is retained in the final product. The value of m can expediently be determined by the viscosity various solutions containing between 60 and 90 wt .-% of the desired amine oxide is measured and the viscosity is plotted against the concentration and the minimum is determined. The existence of the Minimum indicates that the particular amine oxide is suitable for preparation by the process of the invention is and the concentration, which corresponds to the minimum viscosity, gives the value of m.

In the usual embodiment of the invention the amine and the peroxidizing agent are essentially mixed in stoichiometric proportions, although other proportions can be used if there is an excess of one or the other Reaction participant in the product is desired or can be tolerated. In general it is preferred to use a small excess of hydrogen peroxide, preferably after the reaction is complete removed with alkali such as sodium hydroxide. Optionally, the pH can be adjusted using a small amount of a

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Mineral acid, such as hydrochloric acid, can be adjusted. The mixture is preferably left to stand for a period of from 1 to 24 hours, most preferably more than 6 hours, for example 12 hours, at ambient temperature. It is also possible to heat the mixture slightly, for example up to a temperature of about 50 ^° C.

The invention allows for the first time the preparation of concentrated aqueous solutions of amine oxides which are essentially more economical to store, transport and use compared to the diluted ones Prior art products, but providing a process that is just as easy and can be carried out inexpensively like the known manufacturing processes.

The invention is illustrated in more detail by the following examples.

example 1

The viscosities and concentrations of Dime thyldodecylamine oxide determined and plotted against each other, the curve having a minimum at about 70 wt .-% revealed.

The product was then made in the following manner.

Starting materials;

Dimethyldodecylamine: 221 g

Hydrogen peroxide: 75 g

Water: 27 g

Ethylenediaminetetraacetic acid: 0.4 g.

- ν _

Λ-

The amine and Athylendiamintetraessigsäure were mixed and heated to 6O ⁰ C. The hydrogen peroxide and water were mixed and added dropwise to the stirred mixture of the amine and ethylenediaminetetraacetic acid over a period of about 1 hour. When the addition was complete, the mixture was stirred for an additional 19 hours. The analysis of the product obtained gave the following values:

Amine oxide: 70.1% by weight

free amine: 0.03% by weight

Hydrogen peroxide: 0.12% by weight

Water: rest

Example 2

The procedure of Example 1 was _{repeated using N L} dodecyl-tri (oxyethyl) amine.

The minimum was found at 80 wt% amine oxide. It The following amounts were therefore used in the process:

Amine: 400 g hydrogen peroxide (50%): 76 g ethylenediaminetetraacetic acid : 0.8 g

The analysis of the product prepared according to Example 1 gave the following values:

Amine oxide: 75.3% by weight

free amine: 0.85% by weight

Hydrogen peroxide: 0.48% by weight

Water rest

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Removal of residues of hydrogen peroxide

The hydrogen peroxide remaining at the end of the reaction was removed by catalytic decomposition by adding sodium hydroxide. In the following example, 0.1 wt .-% and 1 wt .-% of sodium hydroxide, based on the total weight of the sample added to the product of Example 2 and the mixture stirred at 6O ⁰ C. The following peroxide concentrations were then measured.

Table I.
Peroxide concentrations (weight-96}

Time (Hours) 0, 1% NaOH V / o NaOH 0 1 , 4 1, 4th 1 0 , 86 09 24 0 , 18 O, 06

The sodium hydroxide had no adverse effect on the product and was purified by means of hydrochloric acid after Removal of the peroxide neutralized.

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Claims (9)

Claims 1. / Process for the production of amine oxides by ^ - ^ mixing a tertiary amine, a peroxidizing agent and water, characterized in that a sufficient amount of water is used to the product at a concentration above 60 wt. based on the mixture, to be kept in a pourable state. 2. The method according to claim 1, characterized in that that the tertiary amine used is a trialkylamine in which one of the alkyl groups has 8 to 20 carbon atoms and the other two alkyl groups have 1 to 4 carbon atoms each. 3. The method according to claim 2, characterized in that that a tertiary amine is used, the two lower alkyl groups of which are methyl groups. 4. The method according to claim 2 or 3, characterized in that that one uses a tertiary amine, its a higher one Alkyl group has 12 to 16 carbon atoms. 5. The method according to claim 1, characterized in that a tertiary amine is used, one of which Substituent an alkyl-polyoxyalkylene group with 8 to 20 carbon atoms in the alkyl part and 1 to 20 oxyalkylene units and its other two substituents Represent alkyl groups having 1 to 4 carbon atoms. - 10 - 609826/1 Ü26 6. The method according to claim 5, characterized in that one uses a tertiary amine, the other both lower alkyl substituents are methyl groups. 7. The method according to any one of the preceding claims, characterized in, that an aqueous solution of hydrogen peroxide is used as the peroxidizing agent. 8. The method according to the preceding claims, characterized in that that one uses an amount of water between (m + 5) and (m - 5)% by weight, where m is the concentration of water based on the weight of the mixture Is the minimum of the curve obtained graphically by plotting viscosity against concentration, where this minimum is below a concentration of 40% by weight of water. 9. The method according to claim 8, characterized in that that an amount of water is used which is essentially m% by weight, based on the weight of the mixture. Oo method according to any of the preceding claims, characterized, that the value of m is first predetermined and then a peroxidizing agent is added to a tertiary amine in the presence of an amount of water of (m + 5) to (m - 5)% by weight, based on the weight of the mixture 60982b / 1026