Volatile esters, formation

SHALIT, M., GUTERMAN, I., VOLPIN, H., BAR, E., TAMARI, T., MENDA, N., ADAM, Z, ZAMIR, D., VAINSTEIN, A., WEISS, D., PICHERSKY, E., LEWINSOHN, E., Volatile ester formation in roses. Identification of an acetyl-coenzyme A. Geraniol/citronellol acetyltransferase in developing rose petals. Plant Phys., 2003,131, 1868-1876. 

Shalit, M., et al. (2003) Volatile ester formation in roses. Identification of an acetyl-coenzyme A Geraniol/citronellol acetylfransferase in developing rose petals. Plant Physiol. 131,... 

The preparation of -butyl bromide as an example of ester formation by Method 1 (p. 95) has certain advantages over the above preparation of ethyl bromide. -Butanol is free from Excise restrictions, and the -butyl bromide is of course less volatile. and therefore more readily manipulated without loss than ethyl bromide furthermore, the n-butyl bromide boils ca. 40° below -butyl ether, and traces of the latter formed in the reaction can therefore be readily eliminated by fractional distillation. 

The ultimate levels of esters in fresh and stored apples are determined by the amount of precursors for ester formation, e.g. lipids, which are influenced by cultivar, growing conditions, harvest maturity and storage conditions [47]. In Fuji apples, acetate ester concentrations increase during maturation, 2-methyl-butyl acetate being the major ester component in the volatile compound profile... 

Nordstrom, K., Studies on the Formation of Volatile Esters in Fermenta-... 

Ramey, D.D. Ough, C.S. (1980). Volatile ester hydrolysis or formation during storage of model solutions and wines. J. Agric. Food Chem., 28, 928-934. 

The investigation of poly-ester formation has been carried out using equi-molecular proportions of 1,3 2,4 5,6-tri-0-methylene-n-glucitol and adipic acid in excess trifluoroacetic anhydride, the latter serving as the solvent. After 3 hr. at room temperature, the volatile constituents were removed, and the reaction mixture was treated with an aqueous sodium bicarbonate... 

Plasticizers. Plasticizers are organic liquids of oily consistency and low volatility. Esters of polyamides such as dioctyl phthalate are the most commonly used plasticizers for aiding the film formation of the resin. 

De Footer et al. (1987) demonstrated the ability of Golden Delicious apples to produce aldehydes from exogenously supplied carboxylic acids, which led to the formation of volatile esters. Cold-stored apples efficiently transformed the aldehydes into volatile esters, but controUed-atmosphere (CA) stored fruits seemed to be unable to handle increased concentrations of aldehydes, probably because of changes in the ADH activity in the fruit (De Footer et al. 1987). 

Yamashita I, Nemoto Y, Yoshikawa S (1975) Formation of volatile esters in strawberries. Agric Biol Chem 39 2303-2307... 

Low humidity storage of apples was found to increase the emission of hexyl, isopentyl, and butyl acetate and decrease the corresponding alcohols. The low humidity favored ester formation. Illumination of the apples increased volatile producdion during storage. This increase in volatiles is postulated to be due to the light catalyzing lipid oxidation in the peel. The lipid oxidation products then are metabolized to... 

Esters are quite important to the flavor of both natural foods (e.g., fresh fruit) and fermented foods. Of the fermented foods, esters probably are most important to the flavor of some of the alcoholic beverages. The TNO-CIVO [85] compilation of volatiles in foods lists 94 esters that had been identified in beer. Most of the esters found in beer are formed via primary fermentation. They are produced intracellularly in yeast by enzymatic action [86]. Lipid metabolism by the yeast provides a large number of acids and alcohols that may undergo esterification to yield a variety of esters. While pure chemical reactions can lead to ester formation, this reaction is... 

The ester and catalj st are usually employed in equimoleciilar amounts. With R =CjHs (phenyl propionate), the products are o- and p-propiophenol with R = CH3 (phenyl acetate), o- and p-hydroxyacetophenone are formed. The nature of the product is influenced by the structure of the ester, by the temperature, the solvent and the amount of aluminium chloride used generally, low reaction temperatures favour the formation of p-hydroxy ketones. It is usually possible to separate the two hydroxy ketones by fractional distillation under diminished pressure through an efficient fractionating column or by steam distillation the ortho compounds, being chelated, are more volatile in steam It may be mentioned that Clemmensen reduction (compare Section IV,6) of the hj droxy ketones affords an excellent route to the substituted phenols. 

The question as to whether a flame retardant operates mainly by a condensed-phase mechanism or mainly by a vapor-phase mechanism is especially comphcated in the case of the haloalkyl phosphoms esters. A number of these compounds can volatilize undecomposed or undergo some thermal degradation to release volatile halogenated hydrocarbons (37). The intact compounds or these halogenated hydrocarbons are plausible flame inhibitors. At the same time, thek phosphoms content may remain at least in part as relatively nonvolatile phosphoms acids which are plausible condensed-phase flame retardants (38). There is no evidence for the occasionally postulated formation of phosphoms haUdes. Some evidence has been presented that the endothermic vaporization and heat capacity of the intact chloroalkyl phosphates may be a main part of thek action (39,40). 

Phosphoric acid [7664-38-2] and its derivatives are effective catalysts for this reaction (60). Reverse alcoholysis and acidolysis can, in principle, also be used to produce polyamides, and the conversion of esters to polyamides through their reaction within diamines, reverse alcoholysis, has been demonstrated (61). In the case of reverse acidolysis, the acid by-product is usually less volatile than the diamine starting material. Thus, this route to the formation of polyamide is not likely to yield a high molecular weight polymer. 

Volatiles or Aroma. The essential oil, or aroma, of tea provides much of the pleasing flavor and scent of green and black tea beverages. Despite this, volatile components comprise only - 1% of the total mass of the tea leaves and tea infusions. Black tea aroma contains over 300 characterizing compounds, the most important of which are terpenes, terpene alcohols, lactones, ketones, esters, and spiro compounds (30). The mechanisms for the formation of these important tea compounds are not fully understood. The respective chemistries of the aroma constituents of tea have been reviewed... 

Esters of high volatility, such as methyl formate, methyl acetate, and ethyl formate, have lower boiling points than those of the corresponding alcohols, and therefore can be readily removed from the reaction mixture by distillation. 

Esters of medium volatility are capable of removing the water formed by distillation. Examples are propyl, butyl, and amyl formates, ethyl, propyl, butyl, and amyl acetates, and the methyl and ethyl esters of propionic, butyric, and valeric acids. In some cases, ternary azeotropic mixtures of alcohol, ester, and water are formed. This group is capable of further subdivision with ethyl acetate, all of the ester is removed as a vapor mixture with alcohol and part of the water, while the balance of the water accumulates in the system. With butyl acetate, on the other hand, all of the water formed is removed overhead with part of the ester and alcohol, and the balance of the ester accumulates as a high boiler in the system. 

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