Transesterification phosphorous acid ester

Phosphoric acid esters of the type depicted in 51 were described in a Polish patent. 33 Isomannide and isosorbide bis[2,5-(dipropylphosphite)] (52a and 52b) have been obtained134 by transesterification of propyloxydipropyl-phosphane (53) or dipropylamidodipropylphosphane (54) with the isohex-ide for 5 h at 150° and 142 kPa. 

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. 

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 alkoxy-lated alkylphenols, and neutralizing with phosphoric acid. The product was used as an emulsifying agent for oils and waxes [60]. 

Transesterification (also known as ester exchange, ester interchange, or ester alcoholysis) is the most important of the esterification reactions. Polyesters of relatively low molecular weight (around 2000) prepared from aliphatic dicarboxylic acids and glycols are most commonly made by direct esterification (Section 5.2) with or without addition of an external acidic catalyst. Phosphoric acid, p-toluenesulphonic acid, and antimony pentafluoride have been used as catalysts. The preparation of PET by the direct esterification of TA with ethylene glycol was not practical until the... 

An ester is a compound that, on hydrolysis, yields an alcohol R OH and an organic or an inorganic acid (Fig. 1). The reverse reaction is called esterification. Carboxylic acids (R C02H) and phosphoric acid (H3PO4) are examples of common acids that participate in esterification in nature. In spite of mechanistic similarities, ester hydrolysis and esterification should not be mixed with the term transesterification. 

Thermo-oxidation of PET is catalysed by the metal ions (Zn, Mn etc.) used as catalysts in transesterification of dimethyl terephthalate. Compounds which form complexes with these metal ions inhibit their catalytic action in general and improve the stability of PET towards oxidation. These compounds are mainly esters of phosphoric acid, e.g. triphenyl phosphate (see Table 1). 

Protection of PET from thermal degradation is obtained by removal or deactivation of transesterification catalysts present in PET. Esters of phosphoric acid such as trialkyl or triaryl phosphates can be used for this purpose. Organic phosphites, which are well known to decompose hydroperoxides as secondary antioxidants, are also reported to deactivate metal ions (traces and/or catalyst residues) in polyolefins [4]. In PET, it is suspected that they also deactivate the metal species that catalyse the transesterification reaction. 

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