Hexyl acetate, hydrolysis

Ethyl 2-methylbutanoate, 2-methylbutyl acetate and hexyl acetate contribute most to the characteristic aroma of Fuji apples [49]. In Red Delicious apples, ethyl butanoate, ethyl 2-methylbutanoate, propyl 2-methylbutanoate and hexyl acetate contribute to the characteristic aroma as determined by Charm-Analysis and/or AEDA [50, 51]. In a comparative study of 40 apple cultivars, the highest odour potency or Charm value was found for -damascenone [52]. This compound usually occurs in a glycosidically bound form and is present primarily in processed products owing to hydrolysis of the glycoside bond after crushing fruit cells [53]. -Damascenone has a very low odour threshold with a sweet, fruity, perfumery odour and is not typical of apple aroma in gen-... 

Alkylthio, arylthio, and thioxo. The thioxo group in pyrimidine-2,4-dithione can be displaced by amines, ammonia, and amine acetates, and this amination is specific for the 4-position in pyrimidines and quinazolines. 2-Substitution fails even when a 5-substituent (cf. 134) sterically prevents reaction of a secondary amine at the 4-position. Acid hydrolysis of pyrimidine-2,4-dithione is selective at the 4-position. 2-Amination of 2-thiobarbituric acid and its /S-methyl derivative has been reported. Under more basic conditions, anionization of thioxo compounds decreases the reactivity 2-thiouracil is less reactive toward hot alkali than is the iS-methyl analog. Hydrazine has been reported to replace (95°, 6 hr, 65% 3deld) the 2-thioxo group in 5-hexyl-6-methyl-2-thiouracil. Ortho and para mercapto- or thio- azines are actually in the thione form. ... 

Fig. 19- The efficiency, q, of the Amberlite IR-120 ion exchanger catalyst in ester hydrolysis as a function of the entropy, S, of the parent hydrocarbon RH or R H of the substituents, (a) Hydrolysis (at 25—45°C) of methyl esters RCOOCH3 [366] 1, acetate 2, chloroacetate 3, benzoate 4, cyclopentanecarboxylate 5, phenylacetate 6, a-naphthylacetate 7, 1-octanoate. (b) Hydrolysis (at 35°C) of acetates CH3COOR [480] 1, methyl 2, ethyl 3, cyclopentyl 4, cyclohexyl 5, 1-butyl 6, 2-pentyl 7, 1 -pentyl 8, 1 -hexyl 9, 1 -octyl,...

A great variety of chemical reactions can be advantageously carried out in microemulsions [860-862]. In one of the first papers in this field, Menger et al. described the imidazole-catalyzed hydrolysis of 4-nitrophenyl acetate in water/octane microemulsions with AOT as an anionic surfactant [=sodium bis(2-ethyl-l-hexyl)-sulfosuccinate] [864]. The solubilized water, containing the imidazole eatalyst, is confined in spherical pools encased by surfactant molecules, which have only their anionic head groups (-SOb ) immersed in the aqueous droplets. When the ester, dissolved in water-insoluble organic solvents, is added to this water/octane/AOT/imidazole system, it readily undergoes the catalysed hydrolysis under mild reaction conditions (25 °C). 

The kinetic data in Table 1 demonstrates that S-4 anchimeric assistance is not important in the hydrolysis of acyclic alkyl chlorides [e.g., n-hexyl chloride solvolyzes 1.8 times faster than PhS(CH2)3Cl in 20 mole % aqueous dioxane at 100°C ]. Some data on cyclic systems will be presented here to demonstrate that proximity effects can drastically affect S-4 participation. The formation of (35) and (36) from treatment of 3j -methanesul-fonyloxy-5-a-methylthiocholestane (34) with tetrapropylammonium acetate was rationalized in terms of S-4 participation as shown. Ireland and Smith found that the rates of solvolysis of (37) and (38) were slower [/Crei(77°C) = 0.46 and 0.21, respectively] than the rate for trans-4-t-huty ... 

A wide variety of other specialty monomers are also used to provide specialized performance properties for coating applications. For example, amine functional monomers can be used to improve adhesion to aged alkyd substrates. Specialized monomers can also be used to improve exterior durability, for example VEOVA (vinyl ester of vesatic acid) monomers can improve the hydrolysis resistance of vinyl acetate polymers, and n-butyl methacrylate can be used to enhance the durabiHty of BA-MMA acrylics. Polymer hydrophobicity can be fine tuned by varying the levels of hydrophobic and hydrophilic monomers in the composition and styrene or ethyl hexyl acrylate are used to increase film hydrophobicity and reduce water permeability in BA-MMA systems. Specialty monomers are also used to provide specific chemical functionality to polymer compositions. For example, hydroxyethyl methacrylate can be used to provide hydroxyl functionality to acrylic resins, allowing these polymers to be used in cross-linkable thermoset coatings which cure via melamine chemistry. While specialty monomers are used at relatively low levels in polymer compositions, they frequently provide the performance features needed for the successful application of emulsion polymers in many coating areas. 

---