Esters from acetals

Esters from acetals. Aldehydes are converted to methyl esters by sequential... 

Example Acetic Ester from Acetic Acid and Ethyl Alcohol1... 

Example Acetacetic Ester from Acetic Ester and Sodium1... 

The formation of acetacetic ester from acetic ester, discovered by Geuther in 1863, takes place in accordance with the following equation, r... 

Write the equation for the formation of an ester from acetic acid (CH3GOOH) and ethanol (CgHgOH), and give its name. 

Frankland had a beneficial influence on the teaching of chemistry in England. He wrote some good text-books, one in collaboration with Japp. Frankland s papers were collected and edited by himself but unfortunately the text of the originals is sometimes modified. His researches on organo-metallic compounds, the synthesis of esters from acetic ester, acetoacetic ester, and flame and combustion, and his theory of valency will be dealt with in the... 

It was explained (see p. 528) that two formulae for acetoacetic ester had been proposed, one by Frankland and Duppa and another by Geuther. The formation of acetoacetic ester from acetic ester may be effected either by the action of sodium or sodium ethoxide. Claisen supposed that sodium ethoxide is formed by the action of sodium on traces of alcohol in acetic ester. With ethyl acetate it first forms a derivative of orthoacetic acid, which reacts with ethyl acetate to form the sodium compound of acetoacetic ester ... 

Syntheses with titanium tetrachloride d-Alkoxy-/ -ketocarboxylic acid esters from acetals... 

Zinc-copper titanium tetrachloride p-Alkoxycarboxylic acid esters from acetals Reformatskii-type synthesis with addition of two C-atoms... 

In this experiment, we prepare an ester from acetic acid and a C-4 or a C-5 alcohol. This experiment is a conventional-scale preparation, but it is similar to the microscale preparation of isopentyl acetate, which is described in Experiment 14. However, for the experiment, either your instructor will assign, or you will pick, one of the following C-4 or C-5 alcohols to react with acetic acid ... 

Waldi [181] has separated the esters on silica gel G, using carbon tetrachloride-chloroform (95 + 5). Kauemann et al. [96] have used either tetraUn-hexane (25 + 75) or (50 + 50) for adsorption TLC or paraffin/methyl ethyl ketone-acetonitrile (70 + 30) as reversed phase partition system. All the esters from acetate to stearate yield thus a series of spots like a string of beads. Acetic acid is also a suitable mobile phase, as in PC [125]. Unsaturated fatty acid esters can be differentiated from the saturated esters only with difficulty in this way success is more likely when an adsorption chromatographic separation is carried out... 

Furfuryl acetate. Reflux a mixture of 39 2 g. (34-8 ml.) of redistilled furfuryl alcohol, 48 g. of glacial acetic acid, 150 ml. of benzene and 20 g. of Zeo-Karb 225/H in a 500 ml. bolt-head flask, using the apparatus described under iaoPropyl Lactate. After 3 hours, when the rate of collection of water in the water separator is extremely slow, allow to cool, separate the resin by suction filtration, and wash it with three 15 ml. portions of benzene. Remove the benzene, etc., from the combined filtrate and washings under reduced pressure (water pump) and then collect the crude ester at 74-90°/10 mm. a small sohd residue remains in the flask. Redistil the crude ester from a Claisen flask with fractionating side arm pure furfuryl acetate passes over at 79-80°/17 mm. The yield is 14 -5 g. 

Methylene derivatives ate readily formed in the vapor phase with compounds having a hydrogen in the alpha position to an electron-withdrawing group. Acryhc (40,41) and methacrylic (42) acids (or esters) are produced at 300—425°C from acetic and propionic acids (or esters), respectively, using alkafl and... 

Acidic Cation-Exchange Resins. Brmnsted acid catalytic activity is responsible for the successful use of acidic cation-exchange resins, which are also soHd acids. Cation-exchange catalysts are used in esterification, acetal synthesis, ester alcoholysis, acetal alcoholysis, alcohol dehydration, ester hydrolysis, and sucrose inversion. The soHd acid type permits simplified procedures when high boiling and viscous compounds are involved because the catalyst can be separated from the products by simple filtration. Unsaturated acids and alcohols that can polymerise in the presence of proton acids can thus be esterified directiy and without polymerisation. 

The primary and secondary alcohol functionahties have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undergoes most of the typical alcohol reactions, such as reaction with a free acid, acyl hahde, or acid anhydride to form an ester reaction with alkaU metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial appHcation of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. 

The stringency of the conditions employed in the unmodified cobalt 0x0 process leads to formation of heavy trimer esters and acetals (2). Although largely supplanted by low pressure ligand-modified rhodium-catalyzed processes, the unmodified cobalt 0x0 process is stiU employed in some instances for propylene to give a low, eg, - 3.3-3.5 1 isomer ratio product mix, and for low reactivity mixed and/or branched-olefin feedstocks, eg, propylene trimers from the polygas reaction, to produce isodecanol plasticizer alcohol. 

Treatment of (89) with lead tetraacetate generates the unstable open-ring aldehyde (90) which is quickly converted to a dimethylacetal (91). Following basic hydrolysis of the methyl ester and acetates, the acetal is cleaved with aqueous acid to produce TxB2. A number of other approaches, including one starting from the Corey aldehyde, have been described (58). 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

Alkali metal alkoxides, r-butyl acetate neat, 45°, 30 min, 98% yield of r-butyl ester from methyl benzoate. The rate constant for the reaction increases with increasing ionic radius of the metal and with decreasing polarity of the solvent. Equilibrium for the reaction is achieved in <10 sec. Other examples eire presented. " ... 

From empirical observation, ILs tend to be immiscible with non-polar solvents. They can therefore be washed or brought into contact with diethyl ether or hexane to extract non-polar reaction products. Among solvents of greater polarity, esters (ethyl acetate, for example) exhibit variable solubility with ILs, depending on the nature of the IL. Polar or dipolar solvents (including chloroform, acetonitrile, and methanol) appear to be totally miscible with all ILs (excepting tetrachloroaluminate IL and the like, which react). Among notable exceptions, [EMIMJCl and [BMIMJCl are insoluble in dry acetone. 

Conversion of Acid Anhydrides into Esters Acetic anhydride is often used to prepare acetate esters from alcohols. For example, aspirin (acetylsalicylic acid) is prepared commercially by the acetylation of o-hydroxybenzoic acid (salicylic acid) with acetic anhydride. 

The potassium salt of ethyl o-nitrophenylpyruvate is prepared essentially according to the method of Wislicenus and Thoma.14 However, the isolation of ethyl o-nitrophenylpyruvate has been eliminated by liberating the ester from its potassium salt in the acetic acid used as solvent for the hydrogenation. Catalytic... 

The submitters obtained N-Boc-4-hydroxyproline methyl ester from Synthetech, Inc. [Albany, OR, (503) 967-6575] or Bachem California [Torrance, CA, (310) 530-1571] and dried THF over 4A molecular sieves for two days prior to use (Karl-Fischer titration gave 145 pg/mL water). The checkers purchased N-Boc hydroxyproline methyl ester (97%) and fert-butyl acetate (99+%) from Aldrich Chemical Co. and obtained THF (HPLC grade) from Fisher Scientific. 

A chemist is studying the mechanism of the following hydrolysis reaction of the organic ester methyl acetate CH.COOCI I, + H,0 - CH,COOH + CH,OH. The question arises whether the O atom in the product methanol comes from the methyl acetate or from the water. Propose an experiment using isotopes that would allow the chemist to determine the origin of the oxygen atom. 

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