Esterquats methyldiethanolamine

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. 

Several esterquats have been developed commercially for hair care applications [108-110]. These products are derived from alkanolamines, mainly triethanolamine, methyldiethanolamine, or dimethylamino-l,2-propanediol [111], and preferably fatty adds of vegetable origin like oleic and palmitic sources. Some examples are given in Fig. 15. 

Triethanolamine based esterquats are a mixture of mono- di- and tries-terquats. It is claimed that for softeners and hair conditioners an esterquat with at least 50% diester content is preferred [49]. Methyldiethanolamine-based esterquats are mainly diesterquats with only slight amounts of mono-esterquat. Monoesterquats are useful as cationic surfactants in hair care formulations [124]. Solid esterquats with improved dispersibility and emulsifying properties are obtained by quaternization of fatty acid triethanolamine esters in the presence of a dispersing agent or nonionic emulsifier [125-127]. Esterquats can be used in sprayable conditioning systems for hair care [128]. 

Esterquats prepared from fatty acid methyldiethanolamine esters reacted with diethyl sulfate are useful as emulsifying and consistency-providing agents in cosmetic and/or pharmaceutical preparations [162]. 

Within the last 5 to 8 years, there has developed a need for efficient fabric softening agents with better enviromnental compatability than the most extensively used softening material, dhtdmac [1,5]. Several new types of fabric softener molecules which exhibit rapid biodegradation were developed [6,7], The esterquat shown in Figure 1 is based upon triethanolamine (TEA), while similar diesterquat molecules are in use based upon methyldiethanolamine (MDEA) and l-dimethylamino-2,3-propandiol (dmapd). 

Alcohol amines such as methyldiethanolamine and triethanolamine react with fatty acids to form esteramines. The esteramines have found limited utility and are mostly quaternized to yield the corresponding quats (Figure 2.3). Esterquats are used predominantly in fabric softening, paper softening and hair conditioning applications due to their substantivity and biodegradability [16]. 

---