Fatty acids reactions with alkanolamines

Reaction with Fatty Acids and Esters. Alkanolamines and long-chain fatty acids react at room temperature to give neutral alkanolamine soaps, which are waxy, noncrystaUine materials with widespread commercial appHcations as emulsifiers. At elevated temperatures, 140 —160°C, A/-aIkanolamides are the main products, at a 1 1 reaction ratio (7,8). 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Ester quats with one, two, or three fatty acid ester moieties exist in the molecule, but the dominating type are the diester quats, i.e., products that contain two fatty acid ester chains and two short alkyl groups. These are synthesized by reaction of two moles of fatty acid with one mole of alkanolamine using an acid catalyst under conditions where water is stripped off The fatty... 

Early experiments in the preparation of alkanolamides were begun by Kritchevs-ky (24, 25). It involves condensation reactions of fatty acids, triglycerides, esters, amides, anhydrides, and halides with an alkanolamine. The reaction was carried out at 100-300°C at atmospheric pressure. An important improvement was made by... 

Reaction with Fatty Acids. When alkanolamines react with fatty acids in the ratio of 1 1 at 140-160°C, A -alkylolamides are formed. 

The reaction of methyl esters of fatty acids with alkanolamines is used commercially to prepare high-purity 1 1 alkanolamide. This product, in contrast to the 1 1 alkanolamides prepared from the parent fatty acids, contains only a small quantity of the byproducts or unreacted starting material. 

Alkanolamine-Fatty Acid Condensates Made by reaction of methyl or triglyceride ester of fatty acid with equimolar amount of alkanolamine (about 90% alkanolamide content in product from methyl ester, 80% from triglyceride). Mainly based on coconut or purified coconut (lauric) esters. 

Alkanolamine-Fatty Acid Condensates Made by reaction of 2 mol alkanolamine with 1 mol free fatty acid. Contains about 60-70% alkanolamide, 25-30% alkanolamine, 3-5% fatty acid (as soap of alkanolamine). Mainly based on coconut fatty acid. 

Quatemized esteramines are usually derived from fat or fatty acid which is reacted with an alkanolamine to give an intermediate esteramine. The esteramines are then quatemized. A typical reaction scheme for the preparation of a diester quat is given in Figure 14.8. Two moles of fatty acid methyl ester are reacted with one mole of triethanolamine at 75-115°C in the presence of sodium methoxide catalyst. The resultant esteramine is then quatemized with dimethyl sulfate. Free fatty acids and glycerides have been used in place of the fatty acid methyl ester. 

Different pathways based on different raw material sources are used in technical processes. The original route as described in patents by W. Krichevsky in 1937 is based on the direct condensation of fatty acids with alkanolamines in excess. For the synthesis of diethanol amides, the reaction scheme is shown as follows ... 

The fatty acid is condensated with the alkanolamines without a catalyst. To get high yields of the product, separation of water is essential. To avoid the formation of by-products or even the decomposition of the reactants, the reaction temperature is limited to 430 K. An improved process based on fatty acid methyl esters and stoichiometric amounts of amines was proposed by E. Meade in 1949. 

Alkanolamines are versatile reagents that can be used as starting points for the synthesis of a number of industrial chemicals, including a number of important heterocyclic compounds. The most important of these are the reaction products with long-chain fatty acids to produce neutral alkanol-amine soaps used as emulsifying agents in foods, agricultural sprays, cleansers, cosmetics, and pharmaceuticals. 

Alkanolamine reaction with a long-chain fatty acid such as oleic or stearic acid yields neutral alkanolamine soaps. Soap formation as typified by the reaction of monoethanolamine with stearic acid ... 

Most often, the esterquats are prepared by reaction of a tertiary alkanolamine with a fatty acid, followed by reaction with an alkylating agent to the corresponding quaternary [6]. Other sources of the acyl chain include triglycerides, methyl esters, and acid chlorides. The reaction scheme for the preparation of the diester of bis-2-hydroxyethyldimethylammonium chloride from methyldiethanolamine and fatty acid is given in Fig. 3. 

Complete conversion to the diesteramine is usually not achieved, as this would require very long reaction times and/or an excess of fatty acid. The esterification of alkoxylated alkanolamines with fatty acid can be done in a similar way [6,7]. If the esterification has to be carried out at low temperatures, acid chlorides have to be used instead of a fatty acid [8]. Most acid chlorides will react readily below 100°C. Esterifications in which triglycerides are used are described by Hofinger [9]. 

Esterquats with improved stability and biodegradability are prepared by quaternization of a fatty acid (partially hydrogenated tallow) alkanolamine ester with an alkylating agent (dimethyl sulfate) in the presence of nonionic emulsifiers [126] or cosmetic oils [159]. This procedure avoids problems associated with the use of lower alcohols as solvents in the reaction, such as low ignition point, poor emulsifying capacity for perfume oils, poor skin compatibility, and a defatting action on the skin. Formulations of a triethanolamine-based Coco esterquat, oil, and a Ci-Cg alcohol are useful in cosmetic and sunscreen formulations [160]. 

Early experiments in the preparation of alkanolamides were begun by Kritchevsky (20, 21). It involves condensation reactions of fatty acids, triglycerides, esters, amides, anhydrides, and halides with an alkanolamine. The reaction was carried out at 100-300°C at atmospheric pressure. An important improvement was made by Meade (22), who made use of an alkali metal alkoxide as a catalyst at 100°C at atmospheric and slightly above atmospheric pressure. Fmther refinement was made by Tesoro (23), who conducted the reaction at 55-75°C and a vacuum of 4—8 kPa. Schurman (24) patented a continuous process for making alkanolamide, which makes use of a thin film reactor. It is claimed the short contact time in the reactor produces a high-purity alkanolamide (25). 

Commercial products are mixtures of homologs made by reaction of an alkanola-mine with either a fatty acid or a fatty acid ester, usually triglycerides or methyl esters. An example is the reaction of diethanolamine with coconut oil, which results chiefly in the formation of diethanolamides along with glycerin. Some esters may also be formed, with or without free amine functionality. Frequently encountered ratios of alkanolamine to acid are 2 1 (Kritchevsky type) and 1 1 (4). 

In order to prepare a diesterquat, 2 mol of fatty add is charged to 1 mol of alkanolamine. An acidic catalyst is often used to accelerate the reaction. The temperature is raised to 200°C, and stripping with an inert gas or under vacuum enhances water removal. As esterifications are equilibrium reactions, it... 

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