Formation of esters

The formation of phenolic esters, including those of nonylphenol is much improved by the employment of phosphorous acid as a catalyst. Thus the octanoate ester was obtained in both high conversion and in 95% yield with octanoic acid whereas although sulphuric acid and boric acid afforded almost equal conversions, lower yields (72% and 75% respectively) resulted in both 

2-hydroxybenzophenone can be obtained, a compound of value as a uv absorber in thermoplastics and in packaging material. 

Optically active esters of value in liquid crystal display device applications have been formed from 4-octylphenol with a chiral alkoxybenzoic acid.  

By far the most significant applications of esters derived from nonylphenol have been with the phosphorus oxyacids, namely phosphorous and phosphoric acids, which afford a range of arylphosphites and arylphosphates respectively and with sulphuric acid resulting in the sulphate esters. The salts of these derivatives have found wide industrial usage. 

Tris-4-nonylphenyl phosphite is an important additive useful as an antioxidant for rubber and in lubricating oil as for example in polyesters derived from neopentyl polyol (ref.33) in conjunction with a (Cg or Cg) dialkyidiphenylamine. It has found a use as an additive in radiation-resistant polypropene compositions (ref. 34). 

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Another way to shift the position of equilibrium to favor the formation of ester is by removing water from the reaction mixture This can be accomplished by adding benzene as a cosolvent and distilling the azeotropic mixture of benzene and water... 

Formation of esters of inorganic acids (Section 15 9) Alkyl nitrates dialkyl sulfates trialkyl phos phites and trialkyl phosphates are examples of alkyl esters of inor game acids In some cases these compounds are prepared by the direct reaction of an alcohol and the inorganic acid... 

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. 

Formation of Esters. RBr RCOOCH3 proceeds in 1—2 h by heating a concentrated CH COOK solution with the haUde, with or without... 

Possible uses for these polyhydroxy compounds include the preparation of alkyd-type resins with polybasic acids, the formation of ester plasticizers, and the preparation of surface-active agents. 

Benzoyl Chloride.—The formation of esters by ibe action of benzoyl chloride or othei acid chloride on an alcohol or ]ohcnol in presence of caustic soda is known as the Schotten- 13riumann reaction. The reaction may also be employed in the preparation of deri ati es of the aromatic amines containing i.n acid radical, like benzanilide, CjjH NH.CO... 

THE USE OF POLYSTYRYLSULFONYL CHLORIDE RESIN AS A SOLID SUPPORTED CONDENSATION REAGENT FOR THE FORMATION OF ESTERS SYNTHESIS OF N-[(9-FLUORENYLMETHOXY)CARBONYL]-L-ASPARTIC ACID a tert-BUTYL ESTER, P (2-ETHYL[(lE)-(4-NITROPHENYL)AZO] PHENYL]AMINO]ETHYL ESTER... 

Formation of Ester Intermediates. A number of oxidations involve the formation of an ester intermediate (usually of an inorganic acid), and then the cleavage of this intermediate ... 

Each functional group of an amino acid exhibits all of its characteristic chemical reactions. For carboxylic acid groups, these reactions include the formation of esters, amides, and acid anhydrides for amino groups, acylation, amidation, and esterification and for —OH and —SH groups, oxidation and esterification. The most important reaction of amino acids is the formation of a peptide bond (shaded blue). 

Ester enolates are somewhat less stable than ketone enolates because of the potential for elimination of alkoxide. The sodium and potassium enolates are rather unstable, but Rathke and co-workers found that the lithium enolates can be generated at -78° C.69 Alkylations of simple esters require a strong base because relatively weak bases such as alkoxides promote condensation reactions (see Section 2.3.1). The successful formation of ester enolates typically involves an amide base, usually LDA or LiHDMS, at low temperature.70 The resulting enolates can be successfully alkylated with alkyl bromides or iodides. HMPA is sometimes added to accelerate the alkylation reaction. 

Ozonolysis in the presence of NaOH or NaOCH3 in methanol with CH2C12 as a cosolvent leads to formation of esters. This transformation proceeds by trapping both... 

Nucleophilic Attack at Halogen.- Further applications of tertiary phosphine-tetrahalogenomethane and related "reagents" have been described. The reactions of primary and secondary alcohols with potassium carboxylates in the presence of the triphenylphosphine-tetrachloromethane reagent lead to the formation of esters in good yield. However, application of this procedure... 

The monomeric metaphosphate ion itself commands a fair amount of attention in discussions of metaphosphates. It is postulated as an intermediate of numerous hydrolysis reactions of phosphoric esters 52 S4,S5) and also of phosphorylation reactions S6> kinetic and mechanistic studies demonstrate the plausibility of such an assumption. In addition, the transient formation of ester derivatives of meta-phosphoric acid — in which the double-bonded oxygen can also be replaced by thio and imino — has also been observed they were detected mainly on the basis of the electrophilic nature of the phosphorus. 

Catalytic amounts of I fCl4-AgC104 and Hf(OTf)4 are used for activation of acid halides and acid anhydrides for Friedel -Crafts acylation (Scheme 42) 178 the reactions of both reactive and unreactive aromatic substrates proceed smoothly in the presence of Hf(OTf)4. Furthermore, the Fries rearrangement179,180 and direct C-acylation of phenolic compounds181,182 take place using Hf(OTf)4. Formation of esters and Mannich-type reactions and allylation of imines have been also reported.152... 

Kinetic studies. HERON reactions of 7V-acyloxy-/V-alkoxyamides, which can be conveniently followed by NMR in <74-methanol by monitoring the disappearance of the mutagen or aniline and formation of ester and tetrazene, conform to classical bimolecular kinetics being first order in both mutagen and TV-methyl-aniline.41 43,46,105 Arrhenius parameters and bimolecular rate constants (308 K) for a range of /V- a cy 1 o x y - TV- a 1 k o x y a m i de s 25-30 are collated in Table 5. 

Formation of ester 108 could involve dimerisation of alkoxyamidyls 102 and thermal rearrangement of the hydrazines 107 to esters and nitrogen according to Scheme 12, although a HERON reaction (Scheme 21, pathway (iii)) cannot be discounted under these conditions (vide infra). Anhydrides 101 are almost certainly formed by a HERON reaction (Scheme 21, pathway (ii)). 

In a lipase-catalyzed reaction, the acyl group of the ester is transferred to the hydroxyl group of the serine residue to form the acylated enzyme. The acyl group is then transferred to an external nucleophile with the return of the enzyme to its preacylated state to restart the catalytic cycle. A variety of nucleophiles can participate in this process. For example, reaction in the presence of water results in hydrolysis, reaction in alcohol results in esterification or transesterification, and reaction in amine results in amination. Kirchner et al.3 reported that it was possible to use hydrolytic enzymes under conditions of limited moisture to catalyze the formation of esters, and this is now becoming very popular for the resolution of alcohols.4... 

VI. Reaction of Aldonolactones with Alcohols 1. Formation of Esters... 

At the end of the polymerisation, when species IA has disappeared and ions are present, the addition of styrene makes the ions vanish instantaneously and they remain absent whilst polymerisation proceeds. Moreover, this polymerisation has the same rate constant as the first. This means that it cannot have been initiated only by the acid that was free at that time and that the acid bound as ions must also have become available. These facts are represented by the reaction paths leading to esters IB and IC, which complete the cycle whereby eventually ions are formed again, and can be destroyed again by addition of more monomer. Of course, reaction of the freshly added monomer with the then free acid leads to formation of ester IA. The maximum concentration of carbonium ions increases after each addition because of the increasing double bond concentration, as the polymer concentration increases. Thus the final value of the equivalent conductance and... 

We wish to emphasise that the formation of esters (E) from alkenes (M) and acids (HA), the catalysis of the reactions of E by HA or MtXn, and the activation of E, such as organic chlorides, by the co-ordination of a Lewis acid, such as A1C13, are all very familiar chapters in conventional organic chemistry. It follows that the pseudo-cationic theory is nothing more than a generalisation of conventional organic-chemical ideas and a revival of some pre-Whitmore interpretations which had become occulted by the usefulness and novelty of the carbenium ion concept. 

The alkyl group of the salt of the alkylsulphuric acid can also be made available for esterification if the temperature is raised sufficiently. The formation of esters from acid chlorides or anhydrides need only be recalled here. This method also has practical importance. 

The formation of ester via reaction (11) of Figure 12.10 deserves some further attention as it is not one of the elementary steps discussed in Chapter 2. One possible mechanism is the direct, outer-sphere attack of an alcohol or alkoxide at the acyl carbon atom, similar to the reaction of acid halides and alcohols (17-18 in Figure 12.13). This reaction is accessible for both cis and trans diphosphine complexes 12 and 13. Since monophosphines give mainly trans acyl complexes 13, not suited for insertion reactions, they were thought to have a preference for making esters or low molecular weight products. Trans complexes do form esters in reactions with alcohols or alkoxides, but this does not give direct information about the mechanism [42,43,44],... 

A very efficient pathway to formation of esters by reaction of a carboxylic acid... 

Condensation polymerization is a reaction in which monomers are joined together by the formation of ester or amide bonds. A second smaller product, usually water, is produced by this reaction. For condensation polymerization to occur, each monomer must have two functional groups (usually one at each end of the molecule). 

Anionicallv Activated Alumina. At this time we had also developed an interest in anionically activated alumina. These basic reagents were active in promoting alkylation(42), condensation(43) and hydrolysis(44) reactions. Thus, we impregnated alumina with sodium hydroxide and used this combination both with and without a phase transfer catalyst (benzyltriethyl ammonium chloride). When BTEAC was added, the conversion to ether was decreased and the formation of ester was noted. In the absence of a phase transfer catalyst, the ether became a minor product and methyl phenylacetate became the major product with coproduction of phenylacetic acid. This ester does not result from esterification of the acid as simple stirring of phenylacetic acid with Na0H/A1203 in methanol does not produce methyl phenylacetate. 

A bigger effect for H2O than OH is very unusual and is a behavior certainly not shown by the uncoordinated amide. The effect is ascribed to a benefit from cyclization and concerted loss of protonated amide, without formation of the tetrahedral intermediate. Although the coordinated OH is some 10 times less effective than coordinated HjO (Table 6.4), it is still about 10 times faster with 15 than via external attack by OH at pH 7 on the chelated amide 13. Early studies showed that complexes of the type CoN4(H20)OH can promote the hydrolysis of esters, amides and dipeptides and that this probably arises via formation of ester, amide or peptide chelates. These then hydrolyze in the manner above. 

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