Valeronitrile Hydrolysis in Supercritical Water

Abstract

Nitriles act as important intermediates for the chemical industry and are accessible on a large scale through hydrocyanation or ammonoxidation. Nitrile hydrolysis yields amides and acids used in various applications. The conventional nitrile hydrolysis process relies on stoichiometric amounts of mineral acid or base which inherently deliver great amounts of waste brine. Improving this process towards green chemistry would require reaction conditions which can provide technically significant results without the use of catalysts. Under these conditions, the hydrolysis of valeronitrile in pure supercritical water was investigated. The experiments were performed in a continuous high pressure laboratory-scale apparatus at a temperature between 400 and 500 degrees C, 30 MPa pressure and maximal residence time of 100 s. Nitrile conversion and valeric acid selectivity greater than 90% were achieved.

Homogeneous Catalysis of Valeronitrile Hydrolysis under Supercritical Conditions

“…[3] Similar conversion levels were attained within minutes in pure supercritical water. [21] The behavior of sulfuric acid under supercritical conditions is quite different compared to that at ambient temperature. The second dissociation constant is very small; thus, the first dissociation reaction may be considered as the only source of hydrogen ions.…”

“…Nevertheless, significant valeronitrile conversion and valeric acid (VS) selectivity were achieved at high temperatures. [21] An interesting approach is the combination of both methods-hydrolysis of valeronitrile in dilute sulfuric acid under supercritical conditions. Thus, an assessment of homogeneous catalysis on the reaction rates will be performed, which should deliver similar yields and selectivities at shorter reaction times.…”

Development and Demonstration of a High-Volume Manufacturing Process for a Key Intermediate of Dalcetrapib: Investigations on the Alkylation of Carboxylic Acids, Esters, and Nitriles

“…Concurrently with the development of potent acidic and alkaline hydrolysis conditions, several other potentially appealing approaches were investigated, albeit without ultimate success. Supercritical water at 300 °C, known to convert valeronitrile to valeric acid, achieved maximum 1% hydrolysis, and enzymatic hydrolysis with nitrilases did not yield better than 3% conversion . An exchange reaction with cyclohexanecarboxylic acid ( 3 , Scheme ), analogous to the Mathews reaction, was considered attractive as it did not require other solvents or reagents and could potentially regenerate cyclohexanecarbonitrile ( 10 ), the starting material for the alkylation step .…”

Hydrolysis Kinetics of 2-Pyridinecarboxamide, 3-Pyridinecarboxamide and 4-Pyridinecarboxamide in High-Temperature Water

“…There is a considerable amount of literature on the hydrolysis of amide in HTW, but concentrating on aliphatic and aromatic amides [8,[12][13][14][15][16][17][18][19][20][21][22][23]. The hydrolysis of heterocyclic amides in HTW is rarely reported.…”