Chemical synthesis oxalic acid

Dialkyl Oxalates. Oxalic acid gives various esters, Dialkyl esters ROOC—COOR, are industrially useful, but monoalkyl esters, ROOC— COOH, are not The dialkyl esters are characterized by good solvent properties and serve as starting materials in the synthesis of many organic compounds, such as pharmaceuticals, agrochemicals, and fine chemicals (qv). Among die dieslers, dimethyl, diediyl. and di-n-butyloxalates are industrially important. 

Oxalvl Chloride. This diacid chloride is produced by the reaction of anhydrous oxalic acid and phosphorus pentachloride. The compound vigorously reacts with water, alcohols, and amines, and is employed for tile synthesis of agrochemicals, pharmaceuticals, and fine chemicals. 

Novolac resins are produced commercially from cresol mixtures that contain amounts of m-cresol and p-cresol isomers in varying proportions, depending on the specific application. The reaction proceeds with both metal cation and acid catalysis (Scheme 1.1) Because of strict guidelines for metallic contaminants in semiconductor grade process materials and chemicals, acid catalysis is employed in the synthesis of novolacs used in photoresist applications. In a typical commercial production process, a mixture of m- and p-cresol isomers, formaldehyde (most often in the form of formalin, a 35-40% aqueous solution of formaldehyde) and an oxalic acid catalyst are reacted, following the description of Pampalone ... 

Oxalic acid and oxalates are used as bleaches, metal cleaners, and rust removers and in chemical synthesis and leather tanning. Soluble and insoluble oxalate salts are found in several species of plants. 

In the case of other transition metals, their alkoxides are not suitable as metal sources. Furthermore, a two-step method in which deposited metal salts are solidified by a reaction with oxalate or a base is not suitable for the preparation of ordered macroporous mixed metal oxides. Each metal has a different reactivity with oxalic acid or a base, and the produced oxalate or metal hydoxide has different solubilities in the reacting media, which causes a mixed metal oxide with an undesired metal ratio.On the other hand, in situ methods, in which an additive such as EG, citric acid or EDTA is present with mixed metals, ensure the chemical homogeneity of the products and are suitable methods for producing ordered macroporous mixed metal oxides with a desired ratio. Synthesis methods, structural characterisation and applications of macroporous mixed metal oxides are summarised in Table 3.4. 

The name oxalic acid is derived from one of its sources in the biological world, namely, plants of the genus Oxalis, one of which is rhubarb. Oxalic acid also occurs in human and animal urine, and calcium oxalate (the calcium salt of oxalic acid) is a major component of kidney stones. Adipic acid is one of the two monomers required for the synthesis of the polymer nylon 66. The U.S. chemical industry produces approximately 1.8 billion pounds of adipic acid annually, solely for the synthesis of nylon 66 (Section 16.4A). 

Industrially the main chemical route to glyoxylic acid is the oxidation of glyoxal with nitric acid [15]. A challenge in this synthesis is to prevent overoxidation to oxalic acid and CO2. Electrochem-ically the anodic oxidaticai of glyoxal is possible as well as the cathodic reduction of oxalic acid. Both electrolyses have been investigated thoroughly. 

Synthesis of Isothiazoles, Isothiazolines, and Isothiazolidines 151 From amidoketones and hydrogen sulphide (Type A C-C-C-N + S) 151 From iminonitriles and mercaptoacetic acid derivatives (Type B C-C-N + S-C) 151 From cyclisation of enaminothiones (Type C N-C-C-C-S) 152 From sulphonamidoacetates and diethyl oxalate (N-S-C + C-C) 152 From ketenes and sulphur di-imides (N-S-C + C-C) 152 Physical Properties of Isothiazoles and Isothiazolines 152 Chemical Properties of Isothiazoles, Isothiazolines, and Isothiazolidines 153... 

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