Diethyl phthalate, hydrolysis

Chemical/Physical. Under alkaline conditions, diethyl phthalate will initially hydrolyze to ethyl hydrogen phthalate and ethanol. The monoester will undergo hydrolysis forming o-phthalic acid and ethanol (Kollig, 1993). A second-order rate constant of 2.5 x lO /M-sec was reported for the hydrolysis of diethyl phthalate at 30 °C and pH 8 (Wolfe et al, 1980). At 30 °C, hydrolysis half-lives of 8.8 and 18 yr were reported at pH values 9 and 10-12, respectively (Callahan et al., 1979). 

Yim et al. (2002) studied the sonlytic degradation of diethyl phtahalate in aqueous solution. Degradation followed pseudo-first-order kinetics. Monoethyl phthalate, a hydrolysis product of diethyl phthalate, was approximately 3.3 times higher at pH 12 than at pH 7. The investigators concluded that the reaction was affected by pH of the solution. In the presence of ultrasound, the OH radical reaction, thermal reaction, and hydrolysis were all involved during the reaction. 

Modifications of the 2-Position. One of the primary objectives of the SAR at the 2-position was to prepare ester, amide, alkyl, aryl and halogen derivatives in place of the cyano functionality. A seemingly obvious route to the carboxylate compounds was tivough the hydrolysis of the 2-cyano of compound 1, but it was found to be umeactive toward hydration, which has been attributed to steric hindrance ( . To synthesize other carboxylate entities at the 2-position, we utilized a reaction analogous to that for the preparation of the carbonitrile, 27a by reacting an alkyl acetate or dimethyl acetamide with molten sodium in diethyl phthalate, to give the sodium salts of... 

Kinetic studies of the alkaline hydrolysis of dimethyl and diethyl phthalate, ethyl benzoate, benzyl cinnamate, and diethyl malonate at 298-313 K in aqueous dioxane were reported. Activation parameters were determined for the alkaline hydrolysis of ethyl octanoate in various mixtures of PrOH-water."... 

In an homologous series of phthalate diesters (7.24, R = Me, Et, allyl, 2-methoxyethyl, Bu, i-Bu, and PhCH2), hydrolysis by some human and rat liver carboxylesterases was fastest for the diethyl and diallyl esters [50], This suggested a maximal rate of hydrolysis for phthalate esters with a lipophilic-ity (log P in the octanol/water system) of 3 - 4. Interestingly, and compatible with this interpretation, monoesters were not hydrolyzed. However, that re-gioisomeric monoesters are hydrolyzed clearly indicates that factors other than lipophilicity (e.g., steric factors) are also influential. 

The disappearance of a plasticizer from water can be the result of a number of abiotic and biotic processes that can transform or degrade the compound into daughter compounds that have different physicochemical properties from the parent compound. Hydrolysis is a family of chemical reactions where a plasticizer reacts with water. Phthalate esters may hydrolyze to form monoesters and then dicarboxylic acid. It has been predicted that di-(2-ethylhexyl) sebacate will form 2-ethylhexanol and decanedioic acid. Wolfe et al experimentally measured second-order alkaline hydrolysis rate constants for dimethyl, diethyl, di-n-butyl, and di-(2-ethylhexyl) phthalates, and it appears that hydrolysis may be too slow to have a major impact on the fate of most dissolved plasticizers. The estimated hydrolysis half-lives at pH 7 for 20 plasticizers were longer than 100 days. No information was located for diallyl, ditridecyl and diundecyl phthalates. Under alkaline conditions, hydrolysis may be important for tricresyl phosphate and tri-(2-ethylhexyl) trimellitate at pH 8 their predicted half-lives are 3.2 and 12 days respectively. 

Herbicides may be determined by specific extraction, esterification, and gas chromatographic conditions. Aqueous samples are extracted with diethyl ether and then esterified with either diazomethane or pentafluorobenzyl bromide. The derivatives are determined by GC with an electron capture detector. Compound identifications should be supported by GC-MS for the qualitative confirmation. Alkaline hydrolysis and subsequent solvent wash removes many chlorinated hydrocarbons and phthalates that might otherwise interfere with the electron capture analysis. 

Oligomeric PET model compounds have been widely used to study enzymatic hydrolysis of PET, since their degradation is faster and easier to analyze compared to a polymeric substrate. Diethyl terephthalate (DET), diethyl p-phthalate (DP), h/i(benzoyloxyethyl) terephthalate (PET trimer), ethylene glycol dibenzyl ester (BEB), and hA-(p-methylbenzoic acid)-ethylene glycol ester (PET dimer) have been employed (Eig. 2). Their degradation by PET hydrolases from Fusarium solani [27, 38], T. insolens [1, 5, 48, 101], P. mendocina [25, 49], T. fusca [26, 27, 38], Burkholderia cepacia [26, 27, 38], Aspergillus oryzae [103], Bacillus spp. [87], and porcine liver esterase [109, 110] has been reported, and the corresponding hydrolysis products have been partially characterized (Table 1). 

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