Studies On Hydrolysis Of Nitriles In High Temperature Liquid Water | Posted on:2011-01-12 | Degree:Doctor | Type:Dissertation | Country:China | Candidate:H M Ren | Full Text:PDF | GTID:1111330338972431 | Subject:Biochemical Engineering | Abstract/Summary: | PDF Full Text Request | Nitrile-containing compounds a series of organic compounds containing cyano group, are extensively used in the manufacture of industrial and commercial products. Therefore, the hydrolysis reactions of nitriles have been widely applied in plentiful organic synthesis such as amino acid, amide, carboxylic acid and its derivatives, which is a very significant organic reaction. The traditional methords use strong acid/base to accelerates the hydrolysis of nitriles, which always causes gross pollution.High temperature liquid water, which stands for the pressurized liquid water under the condition of 100~374℃, has some outstanding properties such as highionization constant, high density and low dielectric constant, which gift it acid/base catalysis activity, excellent solubility and self-physical properties adjustability. These unique properties indicate that HTLW having perspective to be applied in organic synthesis. For probing the regularities and mechanism of nitirle hydrolysis in HTLW, studies on the non-catalytic hydrolysis of aromatic nitriles (phenylacetonitrile, 2,6-difluorobenzonitrile) and-cyanopyridine (2-cyanopyridine, 3-cyanopyridine,4-cyanopyridine) and the catalytic hydrolysis of nitriles by adding NH3/CO2 in HTLW were carried out. Accordingly, the reaction regularities of nitriles hydrolysis were discussed based on the hands-on experiment data and available kinetics from literatures. The research work was summarized as below:Phenylacetonitrile and 2,6-difluorobenzonitrile were selected as the model compounds of aromatic nitriles. The kinetics studies on hydrolysis of the aromatic nitriles and their intermediate amides were systematically carried out in HTLW at different initial concentrations and temperatures. The results showed that the hydrolysis of phenylacetonitrile exhibited first-order consecutive kinetics, but 2,6-difluorobenzonitrile exhibited 0.5 order kinetics. The rate constants at different temperature were obtained by the assumption kinetics equation. And the hydrolysis apparent activation energies evaluated by Arrhenius plot were 64.4kJ·mol-1 for phenylacetonitrile and 82.4kJ·mor-1 for phenylacetamide,72.6kJ·mor-1 for 2,6-difluorobenzonitrile and 75.4 kJ·mol-1 for 2,6-difluorobenzamide, and the decarboxylation apparent activation energies was 184.3kJ·mol-1 for 2,6-difluorobenzoic acid.2-cyanopyridine, 3-cyanopyridine and 4-cyanopyridine were selected as the model compounds of cyanopyridines. The kinetics studies on hydrolysis of the cyanopyridines and their intermediate amides were systematically carried out in HTLW at different initial concentrations and temperatures. The results showed that the hydrolysis of all cyanopyridines exhibited typical first-order consecutive kinetics. The rate constants at different temperature were obtained by the assumption kinetics equation. And the hydrolysis apparent activation energies evaluated by Arrhenius plot were 65.2kJ·mol-1 for 3-cyanopyridine and 85.8kJ·mol"1 for nicotinamide, 50.6kJ·mol-1 for 4-cyanopyridine and 62.8kJ·mor-1 for isonicotinamide 90.6kJ·mol-1 for 2-cyanopyridine and 115.4 kJ·mol-1 for picolinamide.Phenylacetonitrile was selected as the model compound. The effects of different additive on nitrile hydrolysis were investigated. The method of adding NH3 into HTLW to accelerate base catalyzed reaction rate was proposed. Hydrolysis kinetics of phenylacetonitrile and phenylacetamide as its intermediate at different ammonia concentrations and temperatures were systematically studied. The NH3 catalyzed hydrolysis apparent activation energies evaluated by Arrhenius plot were 57.2 kJ·mol-1 for phenylacetonitrile and 67.7kJ·mol-1 for phenylacetamide, which are significantly lower than the non-catalytic hydrolysis apparent activation energies. And the NH3 catalyzed hydrolysis of phenylacetonitrile exhibited second-order kinetics instead of first-order kinetics. Moreover, the exploration on CO2-enrihed HTLW reaction system were initialed. The effects of different CO2 loading on phenylacetonitrile hydrolysis were investigated. The hydrolysis rate of phenylacetonitrile in CO2-enrihed HTLW was slower than the rate in HTLW, which is different from NH3-enrihed HTLW.Finally, the hydrolysis data of different nitriles in HTLW were summarized, and and this paper conducts a comprehensive comparsion study on the rate constants and apparent activation energies of aliphatic nitriles, aromatic nitriles, heterocycle nitriles and dicyan-nitriles for the nitrles reaction regularity. Moreover, the factors affecting on the hydrolysis of nitriles were systematically summarized, including reaction temperature, reaction pressure, reaction time and the acid/base additives. | Keywords/Search Tags: | High Temperature Liquid Water, nitriles, phenylacetonitrile, 2,6-difluorobenzonitrile, 3-cyanopyridine, 4-cyanopyridine, 2-cyanopyridine, non-catalyzed, NH3-enriched HTLW, CO2-enriched HTLW, reaction kinetics, hydrolysis regularity | PDF Full Text Request | Related items |
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