Experimental investigation on the thermophysical properties of beryllium oxide-based nanofluid and nano-enhanced phase change material

Journal of Thermal Analysis and Calorimetry - Low thermal conductivity is a primary issue in the development of efficient heat transfer fluids and materials required for the thermal management of...     

Rhodium Enalcarbenoids: Direct Synthesis of Indoles by Rhodium(II)‐Catalyzed [4+2] Benzannulation of Pyrroles

Disclosed herein is the design of an unprecedented electrophilic rhodium enalcarbenoid which results from rhodium(II)‐catalyzed decomposition of a new class of enaldiazo compounds. The synthetic utility of these enalcarbenoids has been successfully demonstrated in the first transition‐metal‐catalyzed [4+2] benzannulation of pyrroles, thus leading to substituted indoles. The new benzannulation has been applied to the efficient synthesis of the natural product leiocarpone as well as a potent adipocyte fatty‐acid binding protein inhibitor.     

An efficient microwave assisted synthesis of novel class of Rhodanine derivatives as potential HIV-1 and JSP-1 inhibitors

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-phenyl-2-thioxothiazolidin-4-one (7a-q) derivatives have been synthesized by the condensation reaction of 3-phenyl-2-thioxothiazolidin-4-ones (3a-h) with suitably substituted 2-(1H-indol-3-yl)-2-oxoacetaldehyde (6a-d) under microwave condition. The thioxothiazolidine-4-ones were prepared from the corresponding aromatic amines (1a-e) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a-h) were synthesized from the corresponding acid chlorides (5a-d) using HSnBu₃.     

Asymmetric reduction of beta-ketonitriles with a recombinant carbonyl reductase and enzymatic transformation to optically pure beta-hydroxy carboxylic acids

Alpha-ethylation is concomitant with the reduction of aromatic beta-ketonitriles catalyzed by whole-cell biocatalysts. Use of isolated carbonyl reductase has completely eliminated this competing reaction. (R)-beta-Hydroxy nitriles were obtained via a reduction catalyzed by a recombinant carbonyl reductase with excellent optical purity and were further converted to (R)-beta-hydroxy carboxylic acids via a nitrilase-catalyzed hydrolysis. The present study allows ready access to both chiral beta-hydroxy nitriles and beta-hydroxy carboxylic acids of pharmaceutical importance.     

A facile synthesis of novel 3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones using microwave heating

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (7a–w) have been synthesized by the Knoevenagel condensation reaction of 3-(aryl/alkyl-2-ylmethyl)-2-thioxothiazolidin-4-ones (3a–d) with suitably substituted 2-(1H-indol-3-yl)2-oxoacetaldehydes (6a–g) under microwave conditions. The thioxothiazolidin-4-ones were prepared from the corresponding aryl/alkyl amines (1a–d) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a–g) were synthesized from the corresponding acid chlorides (5a–g) using HsnBu₃.     

Novel Chiral,Sulfur-Containing Heteroarotinoids with Liquid Crystal Properties

Synthetic methods were developed to prepare ethyl (E)-4-[2-(3,4-dihydro-2-n-octyl-1-oxy-2H-1-benzothio-pyran-6-yl)-1-propenyl]benzoate ( 1 ) and ethyl (E)-4-[2-(3,4-dihydro-2-n-octyl-2H-1-benzothiopyran-6-yl)-1-propenyl]benzoate ( 10 ). These are the first examples of heteroarotinoids which possess properties of liquid crystals. The properties were evaluated using differential scanning calorimetry and by use of polarizing micrography. Both displayed textures which are typical of a smectic or cholesteric phase.     

A novel validated LC method for quantitation of lopinavir in bulk drug and pharmaceutical formulation in the presence of its potential impurities and degradation products

A simple isocratic liquid chromatographic method was developed for determination of lopinavir from its related impurities and assay for the first time. This method involves the use of a C(8) (Symmetry Shield RP8, 150 x 4.6 mm, 5 microm) column. The method was validated over the range of limit of quantitation (LOQ) to 120% of impurity specification limit and LOQ to 150% of working concentration for assay. The mobile phase consisted of a mixture of 50 mM of potassium phosphate buffer, acetonitrile and methanol in the ratio of 40:50:10. The flow rate was set at 1.0 mL/min with UV detection monitored at 210 nm. The drug was subjected to stress conditions of hydrolysis, oxidation, photolysis and thermal degradation. The developed method was validated for linearity, range, precision, accuracy and specificity. This method was successfully applied for content determination of lopinavir in pharmaceutical formulations. The method can be conveniently used in a quality control laboratory for routine analysis for assay and related substances as well for the evaluation of stability samples of bulk drugs and pharmaceutical formulations.     

Development and validation of a reverse-phase liquid chromatographic method for assay and related substances of abacavir sulfate

A simple isocratic liquid chromatographic method was developed for the determination of abacavir from its related substances and assay for the first time. This method involves the usage of C18 (Intertsil octadecyl silane-3V, 150 mm x 4.6 mm, 5 microm) column. The method was validated over the range of 0.002-0.1 mg/mL for chloro impurity, 0.005-0.1 mg/mL for amino impurity and pyrimidine impurity, and 0.005-0.2 mg/mL for abacavir. The mobile phase consists of a mixture of 10 mM ammonium acetate buffer and ACN in the ratio of 90:10. The flow rate was set at 1.0 mL/min with UV detection monitored at 214 nm. The drug substance was subjected to stress conditions of hydrolysis, oxidation, photolysis, and thermal degradation. The developed method was validated for linearity, range, precision, accuracy, and specificity. This method can be conveniently used in a quality control laboratory for routine analysis of both related substances and assay.