Synthesis of ethyl-α- propargyl acrylate - a useful five carbon synthon

The title compound has been synthesised via an alkylation, Wittig-Horner reaction sequence, Michael addition of several active methylene substrates with compound 1 has been carried out.     

Synthesis of trans -N-2-aryl(heteryl)ethenamidines

2-Amino-2-arylethylamides1 carrying electron-donating substituents in thepara position are transformed by hot POC1₃ to the the title compounds2, presumably via iminochlorides 7 and imidazolium derivatives8. Amides lacking this para-substituent give rise to chloroamidines11 under these conditions.m-Methoxyphenethylamide1t and POCl₃ form, besides11f, an isoquinoline derivative3. The involvement of an imidazolium compound8 in the formation of ethenamidines has been verified by the synthesis of2a from10. Reaction of amide1w with PCl₅ in the cold leads to, besides the chloroamidine11c, thecis-ethenamidine12 which equilibrates with thetrans-isomer2o in hot toluene. Thienylethyl urea13 converted by hot POCl₃ to the imidazoline16, while phenylpropylamide17 forms only the iminochloride18a. Contribution No. 752 from Research Centre     

The hydrogen bonding in 1-ethynyl-2-(2′-carbethoxy-1′-vinyl)-2,3-dimethyl-6-isopropyl-cyclohexan-1-ol

The X-ray crystal structure of the title compound, C₁₈H₂₈O₃, is determined. The hydrogen bond scheme does not follow considerations based on hierarchies of donor and acceptor strengths. The hydroxyl group of the molecule accepts only very weak C–H···O interactions.     

Synthesis of new dibenzo nitrogen-oxygen donor macrocycles containing two amide groups

Four new nitrogen-oxygen, dibenzo macrocyclic ligands containing two amide groups have been prepared by combining a dibenzo-containing diamidodialdehyde with an appropriate diamine followed by reduction of the intermediate bis Schiff-base. The starting dibenzo-containing diamidodialdehyde was prepared by treating 2 equivalents of salicylaldehyde with a bis(α-chloroamide).     

Scaling of mean square vorticity in turbulent flows

In self-preserving turbulent wall flows, both measurements and direct numerical simulations indicate that the mean square vorticity in the outer region does not depend only on and U . It also depends on the Reynolds number.RAA is grateful to St. Francis Xavier University (Antigonish) for their support while on study leave there. The support of ARC is gratefully appreciated.     

A reinvestigation of the reaction between titanium(iv) and salicylic acid in concentrated sulphuric acid

It is shown that the coloured species formed between TiO(2+) and salicylic acid in concentrated sulphuric acid may be a pi-complex rather than a chelate. Similar species are formed by other hydroxybenzoic acids where chelating sites for TiO(2+) are not available. The ultraviolet and NMR spectral characteristics of hydroxybenzoic acids in water, concentrated sulphuric acid and deuterochloroform are presented as evidence for the pi-complex formation. The reaction of VO(2+) with salicylic acid in concentrated sulphuric acid is shown to be due to increasing electron-donation in the pi-component of the V-O bond of VO(H(2)O)(5)(2+) as the concentration of sulphuric acid is increased, and not to the presence of salicylic acid.     

Novel routes for the generation of structurally diverse labdane diterpenes from andrographolide

Andrographolide 1, the major constituent of the Indian medicinal plant Andrographis paniculata (Acanthaceae) was converted into the key intermediate 4 by selective oxidative degradation of the C-12,13 olefin bond. The aldehyde functional group present in 4 has been utilized for synthesizing a number of structurally diverse labdane diterpenes. Synthesis and in vitro cytotoxic activity results of the compounds prepared are discussed.     

Thermal characterisation of calcium ferrites by laser flash method

The thermal constants, viz., thermal diffusivities, specific heat capacities and thermal conductivities of samples of mono- and di-calcium ferrites, prepared in the laboratory, have been obtained by laser flash method using an Ulvac-Sinku-Riko TC-3000 series instrument. The temperature range used was from 298–1100 K. All possible thermodynamic parameters associated with the heat capacity data were also calculated.