DK145855B - PROCEDURE FOR SULPHATING ETHOXYLERED SECONDARY ALCOHOLS - Google Patents

Description

o 1 145855

The present invention relates to a process for sulfating ethoxylated secondary alcohols of the general formula R the ethoxylate is converted into a thin flowing film maintained at a temperature not exceeding 80 ° C and contacted within a period of up to 30 seconds with a stream of a mixture of SC> 3 and diluent gas having an SC> 3 concentration of 1-4% by volume, after which the reaction mixture is neutralized.

Products of the above formula are difficult to sulfate in good yields because during the sulfation step they decompose to the original alcohol and ethylene oxide.

This degradation causes the foaming properties of the final product to deteriorate, although some sulfated products having surfactant properties are formed. Furthermore, after neutralization, these partially sulfated products are unstable when used in detergent products, e.g. liquid detergents.

It is known from US Patent No. 3,427,342 to sulfate an ethoxylated secondary alcohol such as lauryl alcohol (Example 5) with a sulfur trioxide-air mixture containing 3.5% SO of 0.1-1 sec, with the reaction mixture cooling rapidly as it emerges from the reaction zone. After a stay in a cooled collection tank, the sulfated product is recycled and reintroduced with the 5: 1 alcohol reactant. Finally, the finished sulfated product is neutralized with caustic soda.

The process according to the invention is characterized in that the mixture of SC> 3 and diluent gas is passed over the thin film at a rate of up to approx. 40 meters per second, that the molar ratio of SC> 3 to ethoxylate is less than 1.4: 1 and that the sulfated product is subjected to immediate neutralization.

35 2 145855 o

This results in sulfation to a surprisingly high degree of conversion, especially when considering how difficult secondary alcohols are to effectively sulfate. This is particularly related to the immediate neutralization 5 of the sulfated product, which has been shown to avoid the decomposition of initially added ethoxylate and sulfuric acid. Also, the above recycle as known from the US patent is saved.

In the sulphation process, a thin, 10 flowing film of ethoxylated secondary alcohol is formed which is kept at a temperature below 80 ° C and kept in contact with a stream of a SO 2 / diluent gas mixture for up to approx. 30 sec at a SO-j concentration of 1 to 4 volume percent. The gas velocity according to the invention is up to approx. 40 meters per

15 seconds and the molar ratio of SO3 to ethoxylate is less than 1.4: 1. Preferably, the SO 1 and approx. 3%. Examples of diluent gas are air, nitrogen and carbon dioxide, of which air is the commonly used gas.

Preferably, the temperature is not above 70 ° C, and in particular it is between 50 and 70 ° C. The contact time is preferably less than about. 10 seconds. The gas velocity according to the invention is preferably below 36.5 m / sec, and in particular it is between 30 and 35 m / sec, and the molar ratio of SC> 3 to ethoxylate is preferably less than ca. 1.2: 1.

According to the invention, the product is subjected to an obvious neutralization during the use of e.g. a solution of sodium, potassium or ammonium hydroxide. Immediate neutralization means that no more than 10 seconds are left before the sulfated product is brought into contact with the neutralizing agent. The sulphating apparatus may contain a puddle of the neutralizing agent into which the product falls after the sulphating. In an alternative method, the stream of the sulfated product is intimately mixed with a stream of the neutralizing agent. The instant neutralization ensures a high conversion of the ethoxylate to the sulfate. If the neutralization is postponed, the product will decompose. It has been found that neutralization stops this disintegration. This is noted in storage, because although deferred neutrality appears to achieve certain foaming properties due to the surfactant ethoxylate decomposition product being surfactant, these foaming properties are less stable and eventually fade after neutralization.

The apparatus used in the practice of the invention is e.g. a fall film reactor of the type disclosed in British Patent Nos. 1,007,994, 1,007,995 and 1,029,029, or a reactor as disclosed in British Patent Nos. 1,080,863 and 1,183,814.

Sulfation of ethoxylated secondary alcohols, hitherto considered far more difficult to sulfate than the corresponding primary products, can now be carried out quickly and efficiently by the process of the invention, which is further illustrated in the following examples.

Example 1

A stream "Tergitol® 15-S-3" (sec. Alcohol ethoxylate) from Union Carbide Co. Ltd. at ambient temperature 20 (about 20 ° C), exactly at a rate of 9.1 kg / h to the liquid feed distributor in a fall film reactor so that the molar passage per peripheral unit is 0.65 gmol / mm / hour.

The reactor consists of a stainless steel tube with a length of 2.4 m, an inside diameter of 20.3 mm and is provided with an external cooling water jacket. A diluted stream of SO ^ in air afica. atmospheric pressure and 100 ° C and with 1.9 vol.% SO 3 are passed to the top of the reactor and flow with the pre-formed liquid film at such a rate that the mole ratio of SO 2 to "Tergitol" ethoxylate is 1.2: 1. ; the surface velocity of the gas stream 30 down through the reactor is 33.5 m / sec.

Cooling water is passed through the cooling jacket of the reactor with an inlet temperature of 25 ° C, so that the temperature of the reacting liquid film is kept at its maximum just below 70 ° C.

At the bottom of the reactor, the gaseous 35 and liquid product phases are rapidly separated by a cyclone system. The liquid stream, which is essentially composed of sec. Alcohol - the ethoxylate sulfuric acid half ester, is immediately neutralized by passing directly into a container containing a calculated amount of 5 wt.% Aqueous solution of caustic soda with vigorous stirring, so that pH - the value of the neutralized paste does not fall below 8.

5 Analysis of the neutralized pasta product gives the following results (in% by weight):

Total purifying agent 31.69

Total solids content 36.72 10 Sodium sulfate 0.47

Sodium hydroxide 0.13

Unreacted sec. Alcohol ethoxylate 6.25

Conversion 79.1% 15 In the final product, only a small trace of olefinic material is found, which shows that only the minor degradation of the desired product has occurred.

A foam test performed on a detergent containing this product yields an acceptable score for commercial purposes.

Example 2

Example 1 is repeated except that the SO3 / air flow contains 4.0% by volume SO3 and has a surface gas velocity of 18.6 m / sec. down through the reactor.

Analysis of the neutralized pasta product gives the following results (in% by weight):

Total purifying active substance 34.31 30 Total solids content 38.71

Sodium sulfate 0.38

Sodium hydroxide 0.02

Unreacted sec. Alcohol ethoxylate 6.93

Conversion 79.2% 35 Only minor traces of olefinic material are found in the final product.

5 145855

ISLAND

A foam test performed on a detergent containing this product gives a score acceptable for commercial purposes.

/ / / / / / / / / / / / 6 145855 o

The presence of purifying agents in the final product is determined by CBS titration and organic differential analysis / showing that the major part of the final sulfating product is the desired sulfated ethoxylate and that only a negligible amount of alcohol sulfate is present due to degradation of the ethoxylate. during the sulphation.