Acidolysis process

Different chemical procedures may be used for the synthesis of alkyd re si ns. The choice is usually dictated by the selection of the starting ingredients. Procedures include the alcoholysis process, the fatty acid process, the fatty acid-oil process, and the acidolysis process. 

A fifth factor is certainly ease of preparation and in this characteristic the melt prepared thermotropic polymers are particularly favored. All of the polymers described thus far may be made in a conventional melt acidolysis process starting with the acetoxy derivatives of the hydroxyl containing monomers used. A typical polymerization scheme is shown in Figure 8, the preparation of the two component polyester derived from the acetylated hydroxybenzoic and hydroxynaphthoic acids. The polymerization may be carried out with or without added catalysts. The poly(ester-amides) commented on here, and the more recently reported aromatic, thermotropic poly(ester-carbonates) and poly(ester-imides), may all be synthesized in a similar manner. 

The acidolysis process, another less commonly used method of forming alkyd resins, is based on the reactions... 

Alkyds are made by different processes, depending upon the available raw materials, final product properties and cost. The alcoholysis process (also called the monoglyceride process) or acidolysis process is used when oil is one of the starting materials, while direct esterification uses fatty acids as starting materials, with better control of final resin properties, but generally at higher cost. 

Figure 2.9 Schematic representation of acidolysis process for alkyd resins 2.3.1.3 Fatty acid process...

The hydrolysis option suffers from the requirement for expensive high-pressure equipment, whilst the lower energy (and capex) acidolysis process suffers from progressive poisoning of the phosphoric acid catalyst by impurities. Reaction with ammonia is quite versatile and can be used to recycle mixtures of both nylon 6 and nylon 6,6. From this, caprolactam, hexamethylene diamine, aminocapronitrile and adiponitrile can all be recovered by distillation. 

Formic acid is currently produced iadustriaHy by three main processes (/) acidolysis of formate salts, which are ia turn by-products of other processes (2) as a coproduct with acetic acid ia the Hquid-phase oxidation of hydrocarbons or (3) carbonylation of methanol to methyl formate, followed either by direct hydrolysis of the ester or by the iatermediacy of formamide. 

The reaction of formate salts with mineral acids such as sulfuric acid is the oldest iadustrial process for the production of formic acid, and it stiU has importance ia the 1990s. Sodium formate [141-53-7] and calcium formate [544-17-2] are available iadustriaHy from the production of pentaerythritol and other polyhydric alcohols and of disodium dithionite (23). The acidolysis is technically straightforward, but the unavoidable production of sodium sulfate is a clear disadvantage of this route. 

It is generally accepted that transamidation is not a concerted reaction, but occurs through the attack of a free end on the amide group via aminolysis (eg, eq. 4) or acidolysis (eg, eq. 3) (65). Besides those ends always present, new ends are formed by degradation processes, especially hydrolysis (eq. 5), through which the amide groups are in dynamic equiUbrium with the acid and amine ends. 

Figure 10.4 Four major polyester depolymerization processes (hydrolysis, alcoholysis, acidolysis, and aminolysis).

The ester (72) (with the OH group appropriately protected) has been transformed into the phosphacyclohexane (75) by way of (73) and (74) by processes of reduction, acidolysis, and peroxide oxidation. Variations of this procedure are also... 

As an alternative process, the nitrone (138 R Cl OCl Ph) yields a mixture of diastereoisomeric (benzyloxymethyl)phosphonic derivatives of which (141) is the main component acidolysis and hydrogenolytic debenzylation lead to phosphoserine (143), the (S) chirality of which was demonstrated by )(-ray analysis of the derivative (144). In a further variation, the di-tert-butyl... 

Transesterification. When esters are heated with alcohols, acids, or other esters in (he presence of a catalyst, the alcohol or acid groups are exchanged. This process is called transesterificaiion. It is accelerated by the presence of a small amount of acid or alkali. Three types of transesterilication are known (/) exchange of alcohol groups (alcoholysis). (2 i exchange of acid groups (acidolysis). and (3) ester-ester interchange. Sec also Esterification. 

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