The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected am inoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

A base polyamide composition comprising a nylon mixture having caprolactam units from 1 wppb to 50 wppm catalyst composition; and greater than 0.75 wt % residual caprolactam, wherein the base polyamide composition has a delta end group level ranging from 30 neq/gram to 90 neq/gram.

The invention provides a continuous preparation method of 2,3,3,3-tetrafluoropropene, comprising the following steps: carrying out liquid-phase catalytic telomerization reaction on ethylene and carbon tetrachloride serving as initial raw materials in the presence of a composite catalyst to obtain a reaction product; performing two-stage membrane separation and purification on the reaction product, and then sequentially performing a primary high-temperature cracking reaction, a gas-phase chlorination reaction, a secondary high-temperature cracking reaction, a primary gas-phase catalytic fluorination reaction and a secondary gas-phase catalytic fluorination reaction to obtain a reaction product; condensing and rectifying the secondary gas-phase catalytic fluorination reaction product to obtain the 2,3,3,3-tetrafluoropropene product.

Provided herein are immobilized chiral phosphoric acids and methods of using immobilized chiral phosphoric acids as catalysts for protecting group reactions.

Chemical processes are disclosed that act to both regenerate and create new catalyst for iron salt catalyzed Kharasch coupling reactions during the process of creating halogenated hydrocarbons. Such processes include loading a reactor with a quantity of Fe(0) metal such as iron wire, supplying CCl.sub.4 to the reactor, supplying a phosphate compound to the reactor, supplying an alkene to the reactor, and supplying a carbonyl of Fe(0) to the reactor.

A platinum-carbon electrocatalyst material comprising a carbon support having a minimum BET surface area of 1000 m.sup.2/g, a nitrogen content of at least 2.5 weight percent, which is present in the form of pyridine, pyridone or pyrrole, a phosphorous content of at least 3 weight percent, which is present in the form of phosphate and phosphonate, and a plurality of platinum nanoparticles dispersed on the carbon support having a maximum average particle diameter of 1.5 nm.

The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected am inoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

Chemical processes are disclosed that act to both regenerate and create new catalyst for iron salt catalyzed Kharasch coupling reactions during the process of creating halogenated hydrocarbons. Such processes include loading a reactor with a quantity of Fe(0) metal such as iron wire, supplying CCl.sub.4 to the reactor, supplying a phosphate compound to the reactor, supplying an alkene to the reactor, and supplying a carbonyl of Fe(0) to the reactor.

The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected aminoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

The present disclosure relates to a process of esterification in presence of a catalyst. The catalyst of the present disclosure is an aryloxy based phosphoric acid having general formula [{ArO}.sub.2P(O)OH] and is represented by the structure: ##STR00001##
wherein, Ar represents aryl compounds. The process of esterification is carried out by the reaction of a carboxylic acid and an alcohol in a fluid medium in the presence of the aryloxy based phosphoric acid catalyst resulting in the corresponding ester. The process of the present disclosure is simple and results in a product having a comparatively higher purity.