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Synthesis of Reactants and Intermediates for Polymers
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Formaldehyde is employed as a basic unit for many industrial adhesives such as the phenolic plastics formed from reaction of phenol and formaldehyde. It also serves as one of the reactants in the formation of amino plastics in the production of urea-formaldehyde (UF) and resins. Formaldehyde can self-condense, forming the cyclic trimer trioxane and the polymer paraformaldehyde. It is industrially produced from the catalytic oxidation of methanol. In turn, hexamethylenetetramine is produced by the condensation of ammonia and 30% aqueous formaldehyde (formalin).
Emerging role of organic acids in leaching of valuable metals from refinery-spent hydroprocessing catalysts, and potential techno-economic challenges: A review
Published in Critical Reviews in Environmental Science and Technology, 2021
Ashish Pathak, Mari Vinoba, Richa Kothari
Citric acid is a tricarboxylic organic acid found in most of the citrus fruits but is most concentrated in lemons and limes. It has wide usages as food additive/preservative. Industrially it is made through the fermentation of carbohydrates using fungi such as Aspergillus niger or Candida sp. The current world production of citric acid is >2.00 million tonnes (Ciriminna, Meneguzzo, Delisi, & Pagliaro, 2017). NTA is another tricarboxylic organic acid, which has wide usages as a chelating agent, dye fixative, and in detergent. Its salts are not known to occur naturally. It was first synthesized by Heintz in 1862. Currently, it is synthesized by an acid process, in which ammonia reacts with formaldehyde to form hexamethylenetetramine. The hexamethylenetetramine is subsequently converted to triscyanomethylamine, and later saponified to form Na3NTA. The production capacity has been estimated at 100 kilotons (Gousetis & Opgenorth, 2011).