40288-64-0Relevant articles and documents
Solvent Isotope Effects on the Kinetics of Nucleophilic Addition of Water to a β-Nitrostyrene
Crowell, Thomas I.
, p. 3294 - 3297 (1983)
The hydrolysis rate of 3,4-(methylenedioxy)-β-nitrostyrene (S) has been measured in H2O and in 99percent D2O buffer solutions from pH -0.9 to 10.6.The kinetic solvent isotope effect (KSIE), k(H2O)/k(D2O), is 6.2 at pH 2.5, where k is independent of pH in both solvents and attains a higher value, approximately 22, at about pH 6.2.The isotope effects ki(H2O)/ki(D2O) on the rate constants for the individual steps of the mechanism have been determined and their contributions to the overall KSIE evaluated.Accordingly, the KSIE on the pH-rate plateau at pH 1-4 can be separated into two factors: 5.0 for K12, the ionization constant of S as a pseudo-base in water; and 1.4 for k3H, the rate constant for rate-controlling protonation of the resulting anion by H3O(1+).At pH 6.2, the higher KSIE (7.6) on k3H2O becomes important while the uncatalyzed addition of water to the double bonds is partly rate controlling.The rate at the midpoint of a proton-inventory plot (49.5percent D2O) shows a negative deviation from linearity of 18percent.
Vasicine from Adhatoda vasica as an organocatalyst for metal-free Henry reaction and reductive heterocyclization of o-nitroacylbenzenes
Sharma, Sushila,Kumar, Manoranjan,Bhatt, Vinod,Nayal, Onkar S.,Thakur, Maheshwar S.,Kumar, Neeraj,Singh, Bikram,Sharma, Upendra
supporting information, p. 5003 - 5008 (2016/10/25)
Vasicine, a quinazoline alkaloid, from the leaves of Adhatoda vasica, has been utilized as an efficient catalyst for metal and base free Henry reaction of various aldehydes with nitro alkanes. The method can be used in the synthesis of various β-nitro alcohols under mild reaction conditions without use of hazardous organic solvents and expensive catalysts. Vasicine is also applied successfully for one pot synthesis of 2,1-benzisoxazoles from o-nitroacylbenzenes in good yields under mild conditions.
Polymer supported DMAP: An easily recyclable organocatalyst for highly atom-economical Henry reaction under solvent-free conditions
Das, Diparjun,Pathak, Gunindra,Rokhum, Lalthazuala
, p. 104154 - 104163 (2016/11/17)
Polymer supported catalysts are regarded as a borderline class of catalysts, which retains the advantages of homogeneous catalysts while securing the ease of recovery by simple filtration and workup of heterogeneous systems. Additionally, such catalysts are less hygroscopic due to the long polymer backbone. Here we have demonstrated that a catalytic amount of polymer supported DMAP (10 mol%) can lead to excellent conversion of an equimolar mixture of aldehyde and nitroalkane exclusively into β-nitroalcohols via the Henry reaction. Unlike most of the commonly used catalysts, polymer supported DMAP can be recovered by simple filtration and reused several times, thereby reducing the operational cost. High synthetic efficiency, total atom economy, near quantitative yields, mild reaction conditions, operational simplicity, easy recovery and reusability of the catalyst, solvent-free reaction conditions and avoidance of traditional reaction workup make the protocol highly significant from Green and Sustainable Chemistry perspectives.
