Proceedings of the Indian Academy of Sciences - Chemical Sciences

Ramachandran Nair, A.; Joshi, B.

doi: 10.1007/BF02844710pmid: N/A

From the ethanol extract of the seeds ofOroxylum indicum a new flavone glucuronide named oroxindin has been isolated. Based on chemical as well as UV, IR, PMR and mass spectral data oroxindin has been constituted as 5-hydroxy-8-methoxy-7-0-β-D-glucopyranuronosyl flavone (wogonin-7-0-β-D-glucuronide).

Madhavan, K.; Srinivasan, V.; Venkatasubramanian, N.

doi: 10.1007/BF02844711pmid: N/A

The kinetics of reaction between benzyl chloride and phenol (or substituted phenols) in the presence of sodium hydroxide have been investigated. A differential application of the effect of substituents on the reaction rate to distinguish between a rate-limiting oxygen or carbon attack has been attempted. Considerable scatter in the Hammett plot for the latter attack points to an essentially O-alkylation. The rate constants correlate well with pKa values of the different phenols. The influence of salt and solvent on the reaction rate suggests this reaction to be an ion-dipole one.

Pradhan, S.; Mathur, H.

doi: 10.1007/BF02844712pmid: N/A

Heats of mixing of the binary mixtures ofn-, sec-, iso- andt-butylamines with methanol were determined in the entire concentration range. All the four systems showed a strong exothermic behaviour. The exothermic heats of mixing vary in the ordert-BuNH2 >n-BuNH2 > sec-BuNH2 > iso-BuNH2. The enthalpy of hydrogen bond in the methanol-butylamine complexes was calculated by means of a thermochemical cycle and found to vary in the ordert-BuNH2 >n-BuNH2 > iso-BuNH2 > sec-BuNH2. This order is different than that found for the hydrogen bond due to self-association. The difference has been explained in the light of steric and electromeric effects arising out of the substitution of the methyl groups in the alkyl chain of the butylamine.

Mohan, S.

doi: 10.1007/BF02844713pmid: N/A

The potential constants of diacetylene molecule has been evaluated using kinetic constants. The other molecular constants such as the generalised vibrational mean amplitudes, shrinkage constants, Coriolis coupling constants and centrifugal distortion constants are also calculated using the vibrational frequencies and the results discussed.

Shankaranarayana, M.; Tantry, K.

doi: 10.1007/BF02844714pmid: N/A

Electronic absorption spectra of a variety of thiocarbonyl and selenocarbonyl compounds have been compared to point out their similarities. Interesting correlations between the absorption maxima and electronegativities of substituents in both the seleno- and thio-carbonyl compounds have been reported.

Bhargava, Shobha; Ray, N.

doi: 10.1007/BF02844715pmid: N/A

Floating spherical Gaussian orbital model is used to discuss the average electric polarisabilities and magnetic susceptibilities of a series of hydrocarbons. It has been noticed that the core contributions are negligibly small and these quantities (average electric polarisabilities and magnetic susceptibilities) can be well estimated from contributions localised on bond Gaussians.

Patel, Rajni; Patel, K.; Mankad, B.; Patel, R.

doi: 10.1007/BF02844716pmid: N/A

o-,p- andm-xylene have been condensed with formaldehyde using paratoluene sulphonic acid as a catalyst and acetic acid/acetic anhydride as a solvent. The xylene-formaldehyde resins thus obtained have been characterised by IR and NMR spectra. The average molecular weight of the resin samples was determined by vapour pressure osmometry. Kinetic parameters were determined by differential thermal analysis, thermogravimetry and differential scanning calorimetry.

Sundaresan, R.

doi: 10.1007/BF02844717pmid: N/A

Reduction of the complexes of zinc, copper and lead at the d.m.e. was reversible and the stability constants were determined from the shift in the half-wave potentials in the presence of mandelic acid. Four complexes were identified for zinc and copper with the overall stability constants 25, 125, 490 and 1380 and 100, 3.3 × 103, 9.6 × 103 and 1.6 × 104 respectively while three complexes were observed for lead with the stability constants 18, 215 and 294. In the case of indium, the reduction of the ‘simple’ ion is irreversible and that of the complex is reversible and hence the system was studied by the method of Momoki and Ogawa. Four complexes, with the stability constants 8.3 × 102, 4.0 × 109 were found to exist.

Sudersanan, M.

doi: 10.1007/BF02844718pmid: N/A

Synergism in the extraction of scandium by a mixture of di-2-ethylhexyl phosphoric acid and a β-diketone has been studied. The nature of the extracted species has been investigated. The effect of temperature on extraction has been studied and synergism has been explained on the basis of thermodynamic parameters of the extraction process.