CS276494B6 - Process for preparing aliphatic amine oxides. - Google Patents

Abstract

The solution concerns a method of preparing aliphatic amine oxides of the above general formula, in which the aliphatic chain may be linear or branched with a number of carbon atoms of 6 to 18. The essence of the solution lies in the use of the principle of interfacial catalysis and solubilizing properties of amine oxides while minimizing undesirable side reactions, which in the case of these compounds lead to the formation of products contaminating the final amine oxide. Long-chain amine oxides have significant surface-active properties and a broad-spectrum antimicrobial effect. They are useful as multifunctional compounds, especially as detergents, with a simultaneous disinfectant and preservative effect in the light, pharmaceutical, cosmetic industries and wherever it is expedient to combine solubilizing* detergent properties and antimicrobial effect. Their detergent effects can also be used for the isolation of membrane proteins.

Description

The invention relates to a process for the preparation of aliphatic trialkylamine oxides of the general formula ⁺ (ch ₃ ) ₂ , wherein R represents an aliphatic linear or branched chain with a number of carbon atoms of 6 to 18.

Several methods are known today for the preparation of aliphatic amine oxides, of which alkyldimethylamine oxides represent the group of the most industrially produced and used compounds. . .

The laboratory approach is the complete alkylation of hydroxylamine with iodoalkanes and subsequent treatment of the alkali metal hydroxides with the resulting ammonium salt. Thus, amine oxides are prepared in relatively low yield, mostly with three identical alkyl groups. This method is not suitable for the industrial production of amine oxides.

By oxidation of tertiary amines with ozone, amine oxides can be prepared in yields of 70% and higher, but the reaction requires halogenated solvents (many of which are carcinogens), possibly methanol (toxic) and catalysts such as e.g. BF 2, AlCl 2, acetic acid and the like.

Another method of oxidizing tertiary amines to amine oxides using peroxyacids - most commonly peracetic, peroxyformic, m-chloroperoxobenzoic or diperoxodisulfur - has the disadvantage that peroxyacids are unstable, must be prepared immediately before use or in situ and are extremely corrosive.

Oxidation with organic hydrogen peroxides (cumene hydrogen peroxide, ethylbenzene hydrogen peroxide, tert-butyl hydrogen peroxide) with catalysis of metal salts V. b and VI also has similar disadvantages. b groups of the periodic table.

The most commonly used method for the preparation of amine oxides from amines is their oxidation with hydrogen peroxide of various concentrations under various conditions. In principle, they can be divided into two groups: oxidation taking place in an organic solvent or in water. For conventional non-aromatic amine oxides, oxidation in an aqueous medium is the most suitable from an industrial point of view. The disadvantage of this method is that initially the reaction proceeds very slowly and only after the formation of a certain amount of product (amine oxide) they accelerate, which in many cases leads to its uncontrolled course (the reaction is exothermic and the temperature of the reaction mixture can reach up to 90-100 ° C). . It is known that at temperatures higher than 60 to 70 ° C there is already a noticeable decomposition of amine oxides, especially to the alkene and e.g. dimethylhydroxylamine. The total reaction time often exceeds 12 hours (temperatures around 60 ° C) and requires a large excess of hydrogen peroxide, especially in the case of long chain tertiary amines.

The process of the invention overcomes the disadvantages of uncontrolled reactions using the principle of interfacial catalysis by adding a small amount of the corresponding amine oxide (e.g. (1-methyldodecyl) dimethylamine oxide) to the emulsion of a tertiary amine (e.g. (1-methyldodecyl) dimethylamine) in water. product of the reaction and which solubilizes the tertiary amine and in such a homogeneous solution the reaction proceeds in a substantially shorter time, the formation of by-products being suppressed to a minimum.

The examples illustrate but do not limit the process for the preparation of tertiary amine oxides according to the invention.

Example 1

22.7 g (0.1 mol) of (1-methyldodecyl) dimethylamine are emulsified in 50 ml of water, (1 + methyldodecyl) dimethylamine oxide is added in an amount so that its final concentration in the solution is 1 mM, the mixture is preheated to 40 ml. to 50 ° C and 22.5 g (0.2 mol) of 30% are slowly added so that the temperature of the reaction mixture does not exceed 60 ° C. It is then stirred at this temperature for a further 5 hours. After cooling, the excess hydrogen peroxide is decomposed with the required amount of 10% aqueous NaHCO 3 or Na 2 CO 3 solution and the amine oxide concentration is adjusted to the desired value by adding or distilling off water. (Isolation of the product gave (1-MECS 276 494 B6 tyldodecyl 2) dimethylamine in 90% yield, mp ¹ 9 93 ° C, _{R f} = 0.75 (silica gel, acetone-HC1, Cjjqji mol.dm = 1, detection by Dragendorf reagent in Munier modification), value of valence vibration of bond N-0 967, 941 cm ¹ (nujol suspension, KBr windows), critical concentration of micelle formation c ^ = 2.10 ^ mol.dm ^, surface tension (y>) 0.1% aqueous solution at 20 ° C is 35 mN.m ¹ ).

Example 2

24.1 g (0.1 mol) of dimethyltetradecylamine are emulsified in 50 ml of water, dimethyltetradecylamine oxide is added in an amount so that its final concentration in the solution is 10 mM and the reaction mixture is heated to 40 ° C. Another procedure is the same as in Example 1, except that hydrogen peroxide is added all at once and the reaction at 60 ° C takes only 4 hours. The yield of dimethyl tetradecylamine oxide is 87%, m.p. 126-129 ° C, (NO) 965 cm ¹ , ^c k ⁼ 2 »? ^x mol.dm3, 0.1% aqueous solution at 20 ° C = 33 mN.m ¹ .

Example 3

31.8 g (0.2 mol) of dimethyloctylamine are emulsified in 50 ml of water, dimethyloctylamine oxide is added in an amount so that its final concentration in the solution is 5 mM, 36.8 g (0.3 mol) of 28% are added all at once. of hydrogen peroxide, the mixture is heated to 40 ° C and allowed to react at this temperature for 8 hours. The other procedure is identical to that described in Example 1. The yield of final dimethylactylamine oxide is 88%, mp 125-128 ° C, V (NO) 964 cm ^-1 , c _k = 1.5 x 10 ¹ mol.dm · ^, γ 0 , 1% aqueous solution is at 20 ° C = 38.5 mN.m ¹ .

Example 4

22.7 g (0.1 mol) of fresh (1-methyldodecyl) dimethylamine or other appropriate tertiary amine and 50 ml of water. This mixture contains on average about 5 mmol of (1-methyldodecyl) dimethylamine oxide or other appropriate amine oxide (determined by polarography, gas chromatography or titration), which serves as a sollubilizer and an interfacial catalyst. After heating the reaction mixture to 40-50 ° C, 24.3 g (0.2 mol) of 28% hydrogen peroxide are added. The further procedure is the same as in Example 1. The yield of final (1-methyldodecyl) dimethylamine oxide is 92%, in the case of other amine oxides, where R = _{CgH2 to á 1g} Hjy are yields of 85 to 95%.

Claims (2)

GS 276 494 B 6 tyldodecyl) dimethylamine oxide in 90% yield, mp 91-93 ° C, R f = 0.75 (silica gel, ace-7-t-HG 1, = 1, detection by Dragendorf reagent in Munier modification), valency value bond vibration N-0 967, 941 cm -1 (nujol slurry, KBr window), critical concentration of cation = 2.10 "mole" · *, surface tension (y>) 0.1% Example 2 24.1 g (0.1 mol) of dimethyltetradecylamine are emulsified in 50 ml of water, dimethyl tetradecylamine oxide is added in an amount to give a final concentration in the water of 50 ml of water at 20 ° C. solution was 10 mM and the reaction mixture was heated to 40 ° C. The other procedure is the same as in Example 1 except that the hydrogen peroxide is added at once and the reaction at 60 ° C is only 4 hours. The dimethyltetradecylamine oxide yield is 87%, mp 126-129 ° C, V (NO) 965 cm-1, ck ~ 2Ί x 1θ ~ 4 mol.dm "0.1% aqueous solution at 20 ° G = 33 mN.m" 1. EXAMPLE 3 31.8 g (0.2 mol) of dimethyloctylamine are emulsified in 50 ml of water, and dimethyloctyl amine oxide is added to give a final concentration of 5 mM in the solution, 36.8 g (0.3%) is added in one portion. mole) of 28% hydrogen peroxide, the mixture is heated to 40 ° C and cannot be reacted at this temperature for 8 hours. The other procedure is as described in Example 1. The yield of dimethyl dimethylactylamine oxide is 88%, mp 125-128 °, V (NO) 964 cm -1, ck = 1.5 x ΙΟ1 mol.dm 3 , γ 0.1% aqueous solution at 38 ° C = 38.5 mN.m "1. Example 4 Into a non-flushed apparatus in which oxidation of (1-methyldodecyl) dimethylamine to (1-methyldodecyl) dimethylamine oxide was previously carried out or another tertiary amine to the corresponding amine oxide after the decomposition step of unreacted hydrogen peroxide, 22.7 g (0.1 mol) of fresh (1-methyldodecyl) dimethylamine or other appropriate tertiary amine and 50 ml of water are added. 5 mmol of (1-methyldodecyl) dimethylamine oxide or other appropriate amine oxide (determined by polarography, gas chromatography or titration) serving as solubilizer and interfacial catalyst, and after heating the reaction mixture to 40-50 ° C, 24.3 g ( 0.2 mol) 28% hydrogen peroxide The process is as thin as in Example 1. The yield of the final (1-methyldodecyl) dimethylamine oxide is 92%, in the case of other amine oxides, where B = CgH4 to (γ is 85 85% to 95%). PATENT CLAIMS A process for preparing aliphatic amine oxides of the general formula R - N + (CH 2) 2, Ι - Ο wherein S is a straight or branched hydrocarbon chain having from 6 to 18 carbon atoms by oxidation with excess hydrogen peroxide in water, characterized in that an emulsion of an aliphatic tertiary amine is oxidized of the formula R - N (CH3) 2, wherein R is the same as above in the presence of R-dimethylamine oxide, where R is the same as above and is always identical to R of the prepared amine oxide, in an amount of 1 to 10 mmol per 100 mmol of tertiary amine at 40-60 ° C for 4-8 hours.