Acetals of esters

Methyl, ethyl, n-propyl, isopropyl, n-hutyl, benzyl, cyclohexyl esters of formic, acetic, oxalic, succinic, tartaric, citric, benzoic, salicylic (and other substituted benzoic acids), phthalic and cinnamic acids phenyl esters of acetic, benzoic and salicylic acids. 

Methyl ketones give esters of acetic acid that is oxygen insertion occurs between the carbonyl carbon and the larger of the two groups attached to it... 

Vinyl acetate [108-05-4] (VAc), CH2=CHOOCCH2, the ethenyl ester of acetic acid, is primarily use for the manufacture of poly(vinyl acetate) [9003-20-7] (PVAc) and vinyl acetate copolymers. Poly(vinyl acetate) homo- and copolymers are found as components in coatings, paints and sealants, binders (adhesives, nonwovens, constmction products, and carpet-backing), and miscellaneous uses such as chewing gum and tablet coatings. AppHcations have grown over the years in a number of areas (1 4). 

You will see, by examining this structure, that aspirin is an ester of acetic acid. Aspirin is mankind s most widely used drug. Somewhat over 20 million pounds of aspirin are manufactured each year in the United States alone This amounts to something like ISO five-grain tablets for every person in the country ... 

Acetylcholine (Ach) is an ester of acetic acid and choline with the chemical formula CH3COOCH2CH2N+ (CH3)3. ACh functions as a chemical transmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in a wide range of organisms, humans included. Neurotransmitter involved in behavioral state control, postural tone, cognition and memory, and autonomous parasympathetic (and preganglionic sympathetic) nervous system. 

The most frequently encountered hydrolysis reaction in drug instability is that of the ester, but curtain esters can be stable for many years when properly formulated. Substituents can have a dramatic effect on reaction rates. For example, the tert-butyl ester of acetic acid is about 120 times more stable than the methyl ester, which, in turn, is approximately 60 times more stable than the vinyl analog [16]. Structure-reactivity relationships are dealt with in the discipline of physical organic chemistry. Substituent groups may exert electronic (inductive and resonance), steric, and/or hydrogen-bonding effects that can drastically affect the stability of compounds. A detailed treatment of substituent effects can be found in a review by Hansch et al. [17] and in the classical reference text by Hammett [18]. 

C-N.m.r. spectroscopy is useful in determining the position(s) of substitution, as esters of acetic and malonic acid, in polysaccharides. This topic is covered in Section VI,6, 8, and 10. 

Acetates are esters of acetic acid. Remember from Chapter 1 that an ester has a signature group... 

Synonyms Acetic acid, propyl ester Acetic acid, /3-propyl ester 1-Acetoxypropane AI3-21456 BRN 1740764 EINECS 203-686-1 FEMA No. 2925 NSC 72025 PrAc //-PrAc Propyl acetate 1-Propyl acetate /3-Propyl acetate Propyl ester of acetic acid /3-Propyl ethanoate UN 1276. 

Synonyms Acetic acid, ethenyl ester Acetic acid, ethylene ester Acetic acid, vinyl ester 1-Acetoxyethylene AI3-18437 BRN 1209327 CCRIS 1306 EINECS 203-545-4 Ethenyl acetate Ethenyl ethanoate Everflex 81L NSC 8404 UN 1301 Unocal 76 Res 6206 Unocal 76 Res S-55 VAc VAM Vinnapas 850 Vinyl acetate H.Q. Vinyl A monomer Vinyl ester of acetic acid Vinyl ethanoate Zeset T. 

Propylbenzene, see Propylbenzene Propyl carbinol, see 1-Butanol Propylene aldehyde, see Acrolein, Crotonaldehyde Propylene chloride, see 1,2-Dichloropropane Propylene dichloride, see 1,2-Dichloropropane a,p-Propylene dichloride, see 1.2-Dichloropropane 1,2-Propylene oxide, see Propylene oxide Propyl ester of acetic acid, see Propyl acetate Propylethylene, see 1-Pentene 5-Propylhexane, see 4-Methyloctane Propyl hydride, see Propane Propylic alcohol, see 1-Propanol Propyl iodide, see 1-Iodopropane n-Propyl iodide, see 1-Iodopropane Propylmethanol, see 1-Butanol Propyl methyl ketone, see 2-Pentanone n-Propyl nitrate, see Propyl nitrate... 

Vinyl ester of acetic acid, see Vinyl acetate... 

Later investigators alcoholyzed imidate salts of other monobasic acids to obtain ortho esters of acetic [13, 14], propionic [15], butyric, valeric, caproic, isocaproic, benzoic [16], and phenylacetic acids [17]. For the latter alcoholysis reactions, the reaction time varies from a few days for the production of methyl orthopropionate to six weeks for ethyl orthobenzoate. McElvain reported that the reaction time is drastically cut by carrying out the reaction in boiling ether [18] or petroleum ether [19]. These conditions provide a reaction temperature below the decomposition point of the imidate salt to the amide. 

Cellulose acetate, which is used in textiles and photographic film, is produced by reacting cellulose with acetic acid and acetic anhydride in the presence of sulfuric acid. Other esters of acetic acid, such as ethyl acetate and propyl acetate, are used in a variety of applications. 

The biosynthesis of the polyketide moiety is thought to involve the condensation of coenzyme A esters of acetic acid with malonyl coenzyme A to give thiol esters of 3-keto acids. Further Claisen condensations with malonyl coenzyme A add further ketone units, leading to 3,5-diketo, 3,5,7-triketo acids and so on as their thiol esters. Intramolecular condensations subsequently afford heterocyclic or aromatic structures (Scheme 275). 

Acetyl-CoA. Acetyl-coenzyme A, a high-energy ester of acetic acid that is important both in the tricarboxylic acid cycle and in fatty acid biosynthesis. 

Diphenyl Malonate and Diphenyl Oxalate. Above 200°C, the half ester of malonic acid decomposes to carbon dioxide and an ester of acetic acid, and the half ester of oxalic acid decomposes to carbon dioxide and an ester of formic acid. Diphenyl malonate and diphenyl oxalate are chain extenders that decrease the terminal PET COOH content by these decomposition reactions. 

Acetylesterase Citrus fruits Ester of acetic acid Alcohol + acetic acid... 

Sucrose Acetate Isobutyrate occurs as a clear, pale yellow, viscous liquid. It consists of a mixture of sucrose esters of acetic and isobutyric acid, with sucrose diacetate hexaisobu-tyrate being the predominant sucrose ester. It is produced through the controlled esterification of sucrose with acetic anhydride and isobutyric anhydride. It is very soluble in essential oils such as orange oil, soluble in ethanol and in ethyl acetate, and very slightly soluble in water. 

The hydrolyses of p-nitrophenyl esters of acetic acid (PNPA), diei lpropionic acid (P ), and lauric acid (PNPL) by Cyclo-(Leu-His), Cyclo-(D-LarfDs), and Cyclo-(Gly-His) as catalyst were carried out (94,103). Following the optical density of p-nitrophenolate ion liberated in the acylation of the imidazole group by the substrate, the seoind-order rate constant (M min ) were determined, and are summarized in Table 16. 

PROP Extract of Acorns calamus L., (Fam. Araceae). Containing asarone, eugenol esters of acetic and heptylic acids. Volatile oil. Yellow to yellowish-brown liquid (viscid) aromatic odor, bitter taste. D 0.960-0.9707 20°/20°. Very sidy sol in water misc with ale. Keep well closed, cool, and protected from light. 

It is exactly this protocol that resolved the lack of selectivity control in the crossed Claisen ester condensation of dissimilar esters, as is shown below for coupling of the esters of acetic and propionic acids ... 

Jencks WP, Gilchrist M. Free energies of hydrolysis of some esters and thiol esters of acetic acid. J. Am. Chem. Soc. 1964 86 4651-4654. 

A-Alkyl-2-methyl-l, 3-benzotellurazolium tetrafluoroborates condense with ortho esters of acetic or propionic acid at 140° to yield A-alkyl-2-(2 -ethoxyalk-r-en-r-yl)-l,3-benzo-tellurazolium tetrafluoroborates, that are converted upon boiling with concentrated hydrochloric acid to A-alkyl-2-(2 -oxo-r,T-alkylidene)-2,3-dihydro-l,3-benzotellurazoles. On heating with phosphorus oxychloride and subsequent treatment with tetrafluoroboric acid these compounds formed 77-alkyl-2-(2 -chloroalk-r-en-T-yl)-l,3-benzotellurazolium tetrafluoroborates. ... 

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