37038-56-5Relevant academic research and scientific papers
Crystal engineering of hand-twisted helical crystals
Saha, Subhankar,Desiraju, Gautam R.
supporting information, 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.
Efficient and selective esterification of aromatic aldehydes with alcohols (1:1) using air as the simplest available oxidant and KCN
Aghapour, Ghasem,Karimzadeh, Maryam
, p. 1013 - 1018 (2017/11/10)
A new and efficient method is described for the oxidative esterification of aromatic aldehydes with different types of alcohols such as primary, secondary, benzylic, allylic and cyclic alcohols and phenols using air as the simplest available oxidant and potassium cyanide in DMF under neutral conditions in high yields. The present method esterifies aldehydes with alcohols in 1:1 molar ratio with excellent chemoselectivity and avoids the use of an external oxidant beside 02 from air.
Evidence of substituent-induced electronic interplay. Effect of the remote aromatic ring substituent of phenyl benzoates on the sensitivity of the carbonyl unit to electronic effects of phenyl or benzoyl ring substituents
Neuvonen, Helmi,Neuvonen, Kari,Pasanen, Paavo
, p. 3794 - 3800 (2007/10/03)
Carbonyl carbon 13C NMR chemical shifts δC(C=O) measured in this work for a wide set of substituted phenyl benzoates p-Y-C 6H4CO2C6H4-p-X (X = NO2, CN, Cl, Br, H, Me, or MeO; Y = NO2, Cl, H, Me, MeO, or NMe2) have been used as a tool to study substituent effects on the carbonyl unit. The goal of the work was to study the cross-interaction between X and Y in that respect. Both the phenyl substituents X and the benzoyl substituents Y have a reverse effect on δC(C=O). Electron-withdrawing substituents cause shielding while electron-donating ones have an opposite influence, with both inductive and resonance effects being significant. The presence of cross-interaction between X and Y could be clearly verified. Electronic effects of the remote aromatic ring substituents systematically modify the sensitivity of the C=O group to the electronic effects of the phenyl or benzoyl ring substituents. Electron-withdrawing substituents in one ring decrease the sensitivity of δC(C=O) to the substitution of another ring, while electron-donating substituents inversely affect the sensitivity. It is suggested that the results can be explained by substituent-sensitive balance of the contributions of different resonance structures (electron delocalization, Scheme 1).
A Novel Synthesis of Phenyl Carboxylates
Hashimoto, Shizunobu,Furukawa, Isao
, p. 2227 - 2228 (2007/10/02)
The direct synthesis of phenyl carboxylates from phenols and carboxylic acids is reported.The reactions proceeded easily when triphenylphosphine and carbon tetrachloride were used as dehydrating agents in the presence of a tertiary amine at room temperature, thus giving esters in high yields.
The Synthesis of Phenyl Carboxylates from p-Bromophenol and Carboxylic Acid
Hashimoto, Shizunobu,Furukawa, Isao
, p. 2839 - 2840 (2007/10/02)
The reaction of p-bromophenol with carboxylic acids in the presence of triphenylphosphine and triethylamine proceeded at a high temperature, with the elimination of hydrogen bromide, to give phenyl carboxylates and small amounts of p-bromophenyl carboxylates.
