33696-03-6Relevant academic research and scientific papers
Crystal engineering of hand-twisted helical crystals
Saha, Subhankar,Desiraju, Gautam R.
, p. 1975 - 1983 (2017/02/15)
A strategy is outlined for the design of hand-twisted helical crystals. The starting point in the exercise is the one-dimensional (1D) plastic crystal, 1,4-dibromobenzene, which is then changed to a 1D elastic crystal, exemplified by 4-bromophenyl 4'-chlorobenzoate, by introduction of a molecular synthon -O-CO-in lieu of the supramolecular synthon Br···Br in the precursor. The 1D elastic crystals are next modified to two-dimensional (2D) elastic crystals, of the type 4-bromophenyl 4'-nitrobenzoate where the halogen bonding and C-H· · ·O hydrogen bonding are well-matched. Finally, varying the interaction strengths in these 2D elastic crystals gives plastic crystals with two pairs of bendable faces but without slip planes. Typical examples are 4-chlorophenyl and 4-bromophenyl 4'-nitrobenzoate. This type of 2D plasticity represents a new type of bendable crystals in which plastic behavior is seen with a fair degree of isotropic character in the crystal packing. The presence of two sets of bendable faces, generally orthogonal to each other, allows for the possibility of hand-twisting of the crystals to give grossly helical morphologies. Accordingly, we propose the name hand-twisted helical crystals for these substances.
Activation parameters of the reactions of 4-nitrophenyl benzoates and S-phenyl benzothioate with 4-chlorophenol in dimethylformamide in the presence of potassium carbonate
Os'Kina,Vlasov
body text, p. 523 - 527 (2009/08/17)
The kinetics of transesterification of 4-nitrophenyl benzoates and S-phenyl benzothioate with 4-chlorophenol in dimethylformamide in the presence of potassium carbonate were studied. Variation of the substrate reactivity and activation parameters of the process is discussed with respect to the substituent in the benzoic acid fragment.
Kinetics of the reaction of 4-nitrophenyl benzoates with 4-chlorophenol in the presence of potassium carbonate in dimethylformamide
Os'kina,Vlasov
, p. 865 - 872 (2007/10/03)
The effect of the substituent in the benzoyl group on the relative rate and activation parameters of transesterification of substituted 4-nitrophenyl benzoates with 4-chlorophenol in dimethylformamide in the presence of potassium carbonate was studied by the competing reaction technique. The whole series of benzoates showed the enthalpy-entropy compensation effect. 4-Nitrophenyl benzoates having electronacceptor substituents give rise to isokinetic relationship with an isokinetic temperature β of 382 K. The mechanism of the transesterification process is discussed. Pleiades Publishing, Inc., 2006.
