Process for the preparation of amphoacetate surfactants

Details Process for the preparation of amphoacetate surfactants Process for the preparation of amphoacetate surfactants

1995-11-22

2001-05-15

Lovering, Richard D. (Department: 1721)

Organic compounds -- part of the class 532-570 series

Organic compounds

Carboxylic acids and salts thereof

C516S203000, C562S565000, C548S300100, C548S352100

Reexamination Certificate

active

06232496

ABSTRACT:

This invention relates to the preparation of amphocetate surfactants.
Amphoacetate surfactants, e.g. those sold under the registered Trade Mark “Miranol”, are customarily made by reacting long chain fatty acids, e.g. in the form of the mixture known as “coconut fatty acids”, with aminoethylethanolamine (AEEA), and reacting the product with a haloacetic acid or salt thereof in the presence of an alkali (see, for example, Kirk-Othmer's Encyclopedia of Chemical Technology Third Edition (Wiley & Sons) Vol. 22, pages 385 and 386 and U.S. Pat. Nos. 2,528,378 or 2,773,068). These reactions may be represented as follows:
RCOOH+H
2
NCH
2
CH
2
NHCH
2
CH
2
OH→RCONHCH
2
CH
2
NHCH
2
CH
2
OH  (I)
and/or
HOCH
2
CH
2
N(COR)CH
2
CH
2
NH
2
  (II)
where RCOOH is the long chain fatty acid. The diamide:
RCONHCH
2
CH
2
N(CH
2
CH
2
OH)COR  (III)
is formed as a by-product.
Both of products I and II may then undergo ring-closure with formation of an imidazoline of formula:
It is preferably to convert this product into the open chain compound of formula I before (or simultaneously with) the reaction with the haloacetic acid in the presence of alkali, e.g. sodium hydroxide, which proceeds as follows:
The product of formula V, obtained in the form of a salt with the alkali used, is amphoteric and constitutes the desired amphoacetate surfactant.
Amphoacetate surfactants may function as anionic, cationic or nonionic surfactants, depending on the pH of the medium in which they are present. They are widely used in cosmetic formulations such as shampoos or cleansing detergents, because of their mildness, safety and lack of irritating effects on skin and eyes. They also have excellent surface active properties such as surface tension reduction, as measured for example by the pC-20 value (i.e. the amount needed to lower the surface activity by 20 units), and excellent foaming and wetting properties. They are compatible with both cationic and anionic surfactants. Because of their biodegradability, lack of skin irritation and unique ability to reduce the irritancy of more aggressive surfactants, such as ether sulfates, amphoacetate surfactants have gained wide use as secondary surfactants in the personal care industry. Furthermore, because of their hydrolytic stability and compatibility with electrolytes, they are also used in household and industrial cleaner formulations.
The haloacetic acid or salt thereof used in making such surfactants, generally sodium chloroacetate, may be involved in a number of side reactions, e.g.
1. Further reaction with amino functions of starting materials or products to produce polycarboxymethylated compounds;
2. Reaction with water to produce glycolic acid derivatives or with glycolic acid derivatives to produce diglycolates; and
3. Reaction with hydroxyethyl groups of starting materials or products to produce the corresponding carboxymethyl ethers.
Of these reactions, reactions of type 2 give rise to undesirable by-products (i.e. glycolates and/or diglycolates), which reduce the amount of haloacetic acid available for the desired reaction to produce the amphoacetate product.
We have found that commercially available coco/lauro amphoacetates contain as impurities (in addition to sodium chloride) the following major organic components:
diamide of formula (III)
Unalkylated amido-amine of formula (I)
Glycolate/diglycolate
sodium monochloracetate, and
Sodium dichloroacetate
The diamide is essentially inert (apart from a small amount of hydrolysis) to the reactions used to form the amphoacetate and so it is present in the product as an impurity. Its presence may be minimised by using an excess of AEEA in the first reaction. The presence of the diamide is undesirable because it causes poor long term stability with hazing and separation of the product.
The following Table shows the glycolic acid content obtained by analysing three commercial amphoacetates:
GLYCOLIC ACID
%
COMMERCIAL PRODUCT I
2.6
COMMERCIAL PRODUCT II
2.4
COMMERCIAL PRODUCT III
2.0
This by-product glycolic acid is present as sodium glycolate. Its presence is undesirable because it does not contribute to the surface active properties of the product.
Sodium monochloroacetate and sodium dichloroacetate are both potential skin irritants and their presence is also undesirable.
The present invention provides a process for the preparation of an amphoacetate surfactant of significantly higher purity than that obtained by previously known methods. The new process comprises reacting a compound of formula
RCONHCH
2
CH
2
NHCH
2
CH
2
OH  (I)
where R is a aliphatic radical of 5 to 19 carbon atoms, with formaldehyde and a cyanide of formula: R
1
CN, wherein R
1
represents a hydrogen atom or an alkali metal, and, where R
1
represents a hydrogen atom, hydrolysing the nitrile obtained with an alkali.
This process may be represented (when hydrogen cyanide and an alkali metal hydroxide are used) as follows:
where R is as defined above and M represents an alkali metal, preferably sodium.
In one embodiment of the process, an alkali metal cyanide is used, normally in aqueous solution. In this embodiment the starting material of formula I may be reacted simultaneously with the formaldehyde and the alkali metal cyanide or first with the formaldehyde and then with the cyanide. The latter method has the advantage of minimising formation of nitrilotriacetic acid (NTA) impurity.
Alternatively, in either of these two methods, the cyanide compound used is hydrogen cyanide itself, and alkali is added subsequently.
The process of the invention is preferably carried out under atmospheric pressure to avoid excessive foaming of the product formed during the reaction. The use of atmospheric pressure, however, prevents the ammonia formed from boiling off. Accordingly, the reaction product is preferably subjected to a distillation step to remove excess water and ammonia. The excess ammonia may also optionally be removed by electrodialysis.
The alkali used in the process of the invention is preferably sodium hydroxide.
The molar ratio of the cyanide and the formaldehyde to the compound of formula I is at least 1:0:1.0 in each case, preferably from 1.2:1.0 to 1.0:1.0.
The starting materials of formula I generally contain mixtures of different R radicals within the range defined above. R is preferably a mixture of saturated and unsaturated aliphatic radicals derived from coconut oil or similar natural oil sources such as palm kernel oil or animal fat sources such as tallow. R is more preferably the residue of mixed coconut oil fatty acids, palm kernel oil fatty acids, a mixture of 70% C
12
-alkyl and 30% C
14
-alkyl fatty acids, or capric, caproic, caprylic, hexadecadienoic, lauric, linoleic, linolenic, margaric, myristic, myristoleic, oleic, palmitric, palmitoleic, or stearic acid, or a mixture thereof. More preferably R is derived from mixed coconut oil fatty acids with the following distribution by weight:
C6 
≦1
C8 
 2-10
C10
4-7
C12
47-55
C14
17-21
C16
 7-13
C18
 7-14
>C18 
  ≦0,5
The reaction is generally conducted at a temperature from about ambient temperature up to as high as about 100° C., preferably between 50° C. and 95° C. After the main reaction is considered complete, a higher temperature may be used to ensure completeness of reaction. The temperature during this portion of the reaction can range as high as 105° C. Suitable reaction times can be easily determined by a skilled artisan.
The product of the process of the invention contains substantially no alkali metal dichloroacetate or alkali metal monochloroacetate. It normally comprises less than 5% by weight, preferably less than 2% by weight, of alkali metal halide, less than 1% by weight of alkali metal glycolate and less than 0.5% of the diamide of formula (III). This unexpected reduction in the amount of diamide allows the possibility of lowering the AEEA: fatty acid radio used in the preparation of compounds of formula (I) and (II) thus reducing the amount of AEEA wasted.
The pr

Affiliated with

Also associated with

Rating

Process for the preparation of amphoacetate surfactants does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for the preparation of amphoacetate surfactants, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of amphoacetate surfactants will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2495746