K. V. Srinivasan

Room temperature ionic liquid promoted synthesis of 1,5-benzodiazepine derivatives under ambient conditions

The reaction of o-phenylenediamines with both acyclic and cyclic ketones in the ionic liquid 1,3-di-n-butylimidazolium bromide afforded 1,5-benzodiazepines in excellent isolated yields in the absence of a catalyst at ambient temperature.

Ionic liquid promoted novel and efficient one pot synthesis of 3,4-dihydropyrimidin-2-(1H)-ones at ambient temperature under ultrasound irradiation

3,4-Dihydropyrimidin-2-(1H)-ones have been synthesized in excellent yields in short reaction time at ambient temperature in the absence of any added catalyst by the reaction of aromatic or aliphatic aldehydes with ethyl acetoacetate (EAA) and urea (or thiourea) in room temperature ionic liquid (IL) under ultrasound irradiation. The evidence for the role of IL in promoting this multicomponent reaction has been given. Based on this evidence, a plausible mechanistic pathway has been postulated.

Regioselective bromination of activated aromatic substrates with N-bromosuccinimide over HZSM-5☆

Abstract The nuclear as well as side-chain bromination of activated aromatic substrates has been achieved in high yields and substantial regioselectivity with N-Bromosuccinimide (NBS) over HZSM-5.

Ultrasound promoted acetylation of alcohols in room temperature ionic liquid under ambient conditions

The O-acetylation of alcohols with acetic anhydride to the corresponding esters has been achieved in excellent isolated yields in short reaction time at ambient conditions under ultrasonic irradiation in the absence of any added catalyst using a room temperature ionic liquid as the medium as well as a promoter for the reaction. The products could be isolated by distillation or selective extraction from the non-volatile ionic liquid, which could be recycled giving rise to a process with minimal waste.

Ionic liquid promoted regioselective monobromination of aromatic substrates with N-bromosuccinimide

Abstract Aromatic substrates were monobrominated regioselectively with NBS in the ionic liquid 1,3-di-n-butylimidazolium tetrafluoroborate [bbim]BF4 in 5 min at 28°C in excellent isolated yields (80–98%) in the absence of a catalyst.

A Novel One‐Pot Synthesis of 2‐Aryl‐4(3H)‐Quinazolinones Using Room Temperature Ionic Liquid as Reaction Medium as well as Promoter

Abstract An efficient one‐pot synthesis of 2‐aryl‐4(3H)‐quinazolinones from 2‐amino benzamides and substituted benzoyl chlorides in a room temperature ionic liquid is described. Compared with the classical reaction conditions, this new synthetic method has the advantages of recyclability of ionic liquid, very good to excellent yields (78–92%), the absence of hazardous and expensive catalysts, and easy workup procedures giving rise to a process with minimum waste.

Polycyclic compounds Part VII. Synthesis laser characteristics and dyeing behaviour of 7-diethylamino-2H-l-benzopyran-2-ones

Abstract Several new 3-substituted benzoxazolyl/benzimidazolyl-7-diethylamino-2H-1-benzopyran-2-one laser dyes have been synthesized and their lasing characteristics evaluated. The spectral properties and dyeing characteristics of the new dyes are also discussed. The dyes 3b 3d and 3g showed great promise as efficient laser dyes with strong possibilities of commercial exploitation. Moreover, the new dyes imparted brilliant greenish yellow shades on polyester with moderate to good fastness properties making them suitable for use as disperse dyes.

HZSM-5 catalysed regiospecific benzoylation of activated aromatic compounds

Abstract HZSM-5 has been shown to display a remarkable reaction selectivity in the liquid-phase benzoylation of activated arenes to benzophenones in high yields.

Selective Alkylation of Phenol with Cyclohexanol over Large-Pore Zeolites

The alkylation of phenol with cyclohexanol has been investigated in the liquid phase without solvent over the H forms of various zeolites in the temperature range 140–220°C. Large-pore zeolites have been shown to be efficient catalysts in such a reaction, and led to the selective formation of para-cyclohexylphenol at higher temperatures. The product selectivity was found to be less dependent on the type of the zeolite structure in the case of large-pore zeolites. A maximum of about 85% for the phenol conversion has been obtained over H-Y and H-mordenite zeolites at 200 °C whereas the conversion is about 72% with H-β. The production of o-alkylated phenol is favored at lower temperatures and p-alkylated product at higher temperatures. The best operating temperature is 200 °C.

CALCINED Mg-Al HYDROTALCITE AS A HETEROGENEOUS BASE CATALYST FOR GEWALD AMINOTHIOPHENE SYNTHESIS

Calcined Mg-Al hydrotalcite (Mg/Al = 4) has been conveniently employed as a heterogeneous base catalyst in the synthesis of 2-amino-3-cyanothiophenes adopting a one pot Gewald aminothiophene methodology.