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Volumn 22, Issue 6, 2003, Pages 1203-1211

Organometallic chemistry in aqueous solution. Hydration of nitriles to amides catalyzed by a water-soluble molybdocene, (MeCp)2Mo(OH)(H2O)+

Author keywords

[No Author keywords available]

Indexed keywords

AMIDES; HYDRATION CATALYST; NITRILE;

EID: 0037451074     PISSN: 02767333     EISSN: None     Source Type: Journal    
DOI: 10.1021/om020845e     Document Type: Article
Times cited : (134)

References (46)
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    • Amides
    • Kroschwitz, J. J., Howe-Grand, M., Eds., John Wiley and Sons: New York
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  • 15
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    • note
    • The rate constants reported for benzonitrile are approximate. Benzamide is not water-soluble, and it precipitates from solution. The slight differences in temperature and concentration that affect the solubility of benzamide in the reaction solution, and therefore the concentration of amide measured by NMR, may cause an error in the calculation of the observed rate constant.
  • 18
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    • note
    • Also note that visual inspection showed a color change from green-brown (the color of the catalyst solution) to pink-brown when pyridine was added to the catalyst solution, consistent with the color change observed when nitriles are added to a solution of the catalyst.
  • 19
    • 0012390349 scopus 로고    scopus 로고
    • note
    • The conversion of succinonitrile to either 3-cyanopropionamide or succinamide is notably high, 100%, likely because the precipitation of the succinamide drives the reaction. The precipitation of the succinamide slows the inhibition reaction as well, leading to high conversion. One might postulate therefore that slightly soluble or nonsoluble amides could be produced readily in high yield using this catalyst without concern about catalyst poisioning (by product inhibition).
  • 20
    • 0012462157 scopus 로고    scopus 로고
    • note
    • This result is expected. Our prior results showed that esters hydrolyze at room temperature in aqueous solution in the presence of the catalyst.
  • 21
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    • note
    • Ether hydrolysis with catalyst 12 is also expected. Our prior studies showed that ethyl vinyl ether hydrolysis proceeded rapidly, producing ethanol and aldehyde within 8 h at 80 °C.
  • 22
    • 0012452445 scopus 로고    scopus 로고
    • note
    • Cyanohydrin (2-hydroxyacetonitrile) is known to rapidly equilibrate between the hydroxyl and aldehyde forms.
  • 23
    • 0012477456 scopus 로고    scopus 로고
    • note
    • As described in the Experimental Section, hydrolysis and substitution reactions were also included where appropriate in the case of bifunctional nitriles.
  • 25
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    • note
    • Factors including pH and water/nitrile ratio can affect the rate of hydration. Previous studies showed that increasing the concentration of hydroxide ions can speed up the elimination of the amide from the catalyst center. Therefore, many catalyst systems are observed to have enhanced performance with the optimization of the solution pH. Because the pH of the catalyst solution after hydration is 6.61, the activity of the catalyst and the rate of the hydration might be enhanced by adjusting the pH. In addition, the water/nitrile ratio is often optimized to compensate for the inhibitory effects observed.
  • 33
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    • note
    • A reviewer points out that the Hammett plot may be biphasic (indicative of a change in the rate-determining step). However, the experimental error in the plotted values prevents one from concluding this with any certainty.
  • 34
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    • note
    • The conversion of 4 to 5 should be facile. First, for intramolecular attack to occur, it is necessary for the sp orbital of the oxygen on the coordinated hydroxide to overlap with the nitrile carbon. The nitrile and hydroxide ligands in 4 are properly disposed for such nucleophilic attack. Second, the crowding caused by the steric bulkiness of the Cp' ligands will facilitate intramolecular attack. Note that hydrolysis of the amide product does not occur with any transition metal hydroxide catalyst that proceeds by an intramolecular pathway. A possible explanation is that formation of a hydrogen-bonded six-membered ring may decrease the nucleophilicity of the hydroxide ligand in these catalysts, thus preventing intramolecular attack on the carbonyl group. For examples of intramolecular -OH attack, see


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.