Carboxylic acids esterifications

Yield ketones after oxidation with Mn02 Yield methyl esters after esterification carboxylic acids... 

Esterification. Carboxylic acids can be esterified by reaction with alkyl halides and DBU in benzene at 25 or 80° (equation I). The reaction is widely applicable to hindered or unstable acids and to BOC- or CBZ-protected amino atids. Yields are invariably high. Triethylamine is of less value as the base. Presumably the hydrogen-bonded complex of DBU and the acid plays a significant role in the reaction. The DBU can be recovered by treatment of the hydrohalide with sodium hydroxide. ... 

Esterification. Carboxylic acids react with alkyl (-butyl ethers in the presence of catalytic amounts of sulfuric acid or p-toluenesulfonic acid to form esters.1 Yields are generally good to excellent. The reaction is carried out by heating the reactants either under reflux or on a steam bath for several minutes until the evolution of isobutylene ceases. 

Esterification. Carboxylic acids are converted into their ethyl esters when heated with an excess of the reagent. Even hindered acids such as 2,4,6-trimethylbenzoic acid are esterified. An acid catalyst usually is not necessary and may be deleterious however, esterification of nicotinic acid and of hippuric acid was accomplished with p-toluenesulfonic acid in dimethylformamide. 

Esterification. Carboxylic acids can be converted into methyl esters in high yield with dimethyl sulfate in the presence of this base as the proton acceptor (10-20% excess amine).1 Ethyl esters can be prepared in the same way using diethyl sulfate. Dicyclohexylethylamine is equally elfective but is not available commercially. The method is simple and rapid and is useful when strongly acidic conditions must be avoided. 

Esterification. Carboxylic acids in the sodium salt form are esterified by various alcohols on heating with the title reagent and BU4NI, Et3N in DMF. 

Esterification. Carboxylic acids react with (1) in CHCI3 or acetonitrile in the presence of 1 eq. of triethylamine to form an active ester (2), which can be isolated if desired. The esters (2) react with an alcohol, again in the presence of 1 eq. of base, to form an ester of the carboxylic acid. The reaction can be carried out in one step by mixing the acid, the alcohol, the coupling reagent, and 2 eq. of base in ether. In either case, the reaction takes place at 20°. Yields are generally in the range of 65-85%. 

Esterification. Carboxylic acids can be esterified by oxidation of a hydra-zone with peracetic acid with a trace of iodine as catalyst (equation I). This... 

An ester is a compound that, on hydrolysis, yields an alcohol R OH and an organic or an inorganic acid (Fig. 1). The reverse reaction is called esterification. Carboxylic acids (R C02H) and phosphoric acid (H3PO4) are examples of common acids that participate in esterification in nature. In spite of mechanistic similarities, ester hydrolysis and esterification should not be mixed with the term transesterification. 

In a process called the Fischer esterification, carboxylic acids are converted into esters when treated with an alcohol in the presence of an acid catalyst. This process is reversible. Esters can also be prepared by treating an acid chloride with an alcohol in the presence of pyridine. 

Esterification Carboxylic acid -1- alcohol — > ester + water 3 Fatty acids + glycerol —-—> triacylglycerol (fat) + 3 water... 

In a process called the Fischer esterification, carboxylic acids are converted into esters when treated with an... 

Acid catalyzed condensation of an alcohol and a carboxylic acid yields an ester and water and IS known as the Fischer esterification... 

Fischer esterification is reversible and the position of equilibrium lies slightly to the side of products when the reactants are simple alcohols and carboxylic acids When the Fis cher esterification is used for preparative purposes the position of equilibrium can be made more favorable by using either the alcohol or the carboxylic acid m excess In the following example m which an excess of the alcohol was employed the yield indicated IS based on the carboxylic acid as the limiting reactant... 

The acyl group of the carboxylic acid acyl chloride or acid anhydride is trans ferred to the oxygen of the alcohol This fact is most clearly evident m the esterification of chiral alcohols where because none of the bonds to the chirality center is broken m the process retention of configuration is observed... 

Although the term ester used without a modifier is normally taken to mean an ester of a carboxylic acid alcohols can react with inorganic acids m a process similar to the Fis cher esterification The products are esters of inorganic acids For example alkyl nitrates are esters formed by the reaction of alcohols with nitric acid... 

Esterification with carboxylic acid anhydrides (Section 15 8) Car... 

The most apparent chemical property of carboxylic acids their acidity has already been examined m earlier sections of this chapter Three reactions of carboxylic acids—con version to acyl chlorides reduction and esterification—have been encountered m pre vious chapters and are reviewed m Table 19 5 Acid catalyzed esterification of carboxylic acids IS one of the fundamental reactions of organic chemistry and this portion of the chapter begins with an examination of the mechanism by which it occurs Later m Sec tions 19 16 and 19 17 two new reactions of carboxylic acids that are of synthetic value will be described... 

Esterification (Section 15 8) In the pres ence of an acid catalyst carboxylic acids and alcohols react to form esters The reac tion IS an equilibrium process but can be driven to favor the ester by removing the water that is formed... 

The answer to this question is critical because it tells us whether the carbon-oxygen bond of the alcohol or a carbon-oxygen of the carboxylic acid is broken during esterification... 

The results of the Roberts-Urey experiment tell us that the C—O bond of the alco hoi IS preserved during esterification The oxygen that is lost as a water molecule must come from the carboxylic acid... 

Hydroxy acids compounds that contain both a hydroxyl and a carboxylic acid function have the capacity to form cyclic esters called lactones This intramolecular esterification takes place spontaneously when the ring that is formed is five or six membered Lac tones that contain a five membered cyclic ester are referred to as 7 lactones, their six membered analogs are known as 8 lactones... 

Esterification of carboxylic acids involves nucleophilic addition to the carbonyl group as a key step In this respect the carbonyl group of a carboxylic acid resembles that of an aldehyde or a ketone Do carboxylic acids resemble aldehydes and ketones m other ways Do they for example form enols and can they be halogenated at their a carbon atom via an enol m the way that aldehydes and ketones can ... 

Section 19 14 The mechanism of acid catalyzed esterification involves some key fea tures that are fundamental to the chemistry of carboxylic acids and then-derivatives... 

From carboxylic acids (Sections 15 8 and 19 14) In the pres ence of an acid catalyst alco hols and carboxylic acids react to form an ester and water This IS the Fischer esterification... 

Fischer esterification m which a phenol and a carboxylic acid condense m the pres ence of an acid catalyst is not used to prepare aryl esters... 

Section 27 5 Ammo acids undergo reactions characteristic of the ammo group (e g amide formation) and the carboxyl group (e g esterification) Ammo acid side chains undergo reactions characteristic of the functional groups they contain... 

Fingerprint region (Section 13 20) The region 1400-625 cm of an infrared spectrum This region is less character istic of functional groups than others but varies so much from one molecule to another that it can be used to deter mine whether two substances are identical or not Fischer esterification (Sections 15 8 and 19 14) Acid cat alyzed ester formation between an alcohol and a carboxylic acid... 

One of the most sensitive tests of the dependence of chemical reactivity on the size of the reacting molecules is the comparison of the rates of reaction for compounds which are members of a homologous series with different chain lengths. Studies by Flory and others on the rates of esterification and saponification of esters were the first investigations conducted to clarify the dependence of reactivity on molecular size. The rate constants for these reactions are observed to converge quite rapidly to a constant value which is independent of molecular size, after an initial dependence on molecular size for small molecules. The effect is reminiscent of the discussion on the uniqueness of end groups in connection with Example 1.1. In the esterification of carboxylic acids, for example, the rate constants are different for acetic, propionic, and butyric acids, but constant for carboxyUc acids with 4-18 carbon atoms. This observation on nonpolymeric compounds has been generalized to apply to polymerization reactions as well. The latter are subject to several complications which are not involved in the study of simple model compounds, but when these complications are properly considered, the independence of reactivity on molecular size has been repeatedly verified. 

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