• B Sanjiva Rao

      Articles written in Proceedings – Section A

    • The occurrence of furan derivatives in volatiles oils

      B Sanjiva Rao K S Subramanian

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      The oil from the leaves ofClausena willdenovii, W. and A., has been found to consist almost entirely of three new bodies belonging to the furan group,α-clausenan C10H12O, di-α-clausenan C20H24O2 andβ-clausenan C10H14O. The former two have been obtained pure and their physical properties recorded. The addition compounds ofα-clausenan with ferro- and ferricyanic acids H4Fe(CN)6·2C10H12O, H3Fe(CN)6·2C10H12O which can be employed both for its purification and estimation, have been described. It is suggested that the acetyl derivative ofβ-clausenan can be employed for its estimation.

    • The occurrence of furan derivatives in volatile oils–II - α-clausenan and di-α-clausenan

      B Sanjiva Rao K S subramaniam

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      The condensation product of α-clausenan and maleic anhydride and the corresponding acid have been described. Di-chloromercury derivatives have been prepared both from α-clausenan and di-α-clausenan. By oxidation with ferrous sulphate, a primary alcohol (α-clausenyl alcohol, C10H14O2) is formed along with an isomeric tertiary alcohol which is easily dehydrated to α-clausenan. Two positions, one of which is α, appear to be free in the furan nucleus of α-clausenan. The formation of a ketone C9H10O2 and a nitro-ketone C9H9NO4 from it indicates the presence of a terminal methylene group.

    • The occurrence of furan derivatives in volatile oils—III - β-clausenan and γ-clausenan

      B Sanjiva Rao K S Subramaniam

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      The analyses of three samples of the volatile oil fromClausena Willdenovii, W. & A. have been given. A component C10H12O, called γ-clausenan, isomeric with α-clausenan and belonging to the furan group has been isolated from the oil. Its physical properties as well as methods for separating it from α- and β-clausenans have been described, β-clausenan has been obtained pure and its properties determined.

    • Effect of surface-active agents on indicators

      T Krishnappa K S Gururaja Doss B Sanjiva Rao

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    • Hysteresis in sorption - XI. Permanence of sorption-desorption hysteresis

      T Krishnappa K Subba Rao B Sanjiva Rao

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      The effect of variation of the temperature of precipitation of gels of hydrous oxides of silica, titania and alumina on the hysteresis effect in the sorption of water vapour has been studied at 30°C. Gels have been obtained by precipitating the hydrous oxides at 25°C. and 100°C. with previous boiling of the silicate solution.

      In all the systems studied, permanent hysteresis loops have been obtained. With increase in the temperature of precipitation, there has been a diminution in the sorptive capacity of gels for water at different partial pressures and in most of the systems the hysteresis loop suffers a diminution in size with a change in the shape and position of the loop. But in none of these systems, is any complete elimination of the loop noticeable. Gels precipitated at 100°C. are less porous than the gels precipitated at 25°C. and appear to have fewer cavities that are responsible for the phenomenon of hysteresis.

    • Hysteresis in sorption - XII. Influence of the temperature of activation of silica gel on the hysteresis effect

      T Krishnappa K Subba Rao B Sanjiva Rao

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      The effect of the activation temperature of silica gel on the hysteresis effect has been studied. Sorption and desorption of water vapour at 30°C. have been conducted on gels activated at 35° C., 70° C., 140° C., 300° C., 500° C. and 1000° C.

      All the gels gave permanent and reproducible hysteresis loops. A marked variation however, was noticed in the total sorptive capacity and the area of the loop.

      The results indicate that from 35° C. to 140° C., there is a decrease in the capillary space in the gel but from 140° C. to 500° C., the capillary space remains practically unaltered. Whereas, above 500° C., the gel suffers structural change, the capillaries collapse and there is a marked decrease in the total capillary volume.

    • Hysteresis in sorption - XIII. Mode of preparation of silica gel and its influence on hysteresis

      T Krishnappa K Subba Rao B Sanjiva Rao

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      By employing the quartz fibre spring technique, the hysteresis in sorption has been studied, of water vapour at 30° C. on precipitated silicic acid gel. A comparative study has been made with regard to the shape and size of the hysteresis loops of precipitated silica gel with that of the adsorbent obtained from silicic jelly.

      The mode of preparation of the gel was found to greatly influence the shape and size of the hysteresis loop.

    • Hysteresis in sorption - XIV. Influence of the temperature of activation of titania gel on the hysteresis effect

      R S Subramanya K Subba Rao B Sanjiva Rao

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      The effect of variation of activation temperature on the hysteresis effect has been studied for titania gel. Sorption and desorption of water vapour at 30°C. on titania gels activated at 30°C., 97°C., 214°C, 400°C., 600°C. and 1000°C. have been measured.

      At different temperatures of activation, permanent and reproducible hysteresis loops have been obtained. There is however, a marked variation in the total sorptive capacity, the area of the hysteresis loops and the relative vapour pressures corresponding to the tail end of the hysteresis loops.

      The results indicate that with an increase in the temperature of activation from 30°C. to 97°C., there is a small increase in the total capillary space and in the total cavity volume. Above 97°C., the gel suffers a structural change with a diminution in capillary space and in cavity volume. There is also a collapse of the smaller cavity necks. At 1000°C., there is a breakdown of the gel structure and a complete collapse of the capillary space.

    • Hysteresis in sorption - XV. Hysteresis in the Sorption of water on casein egg albumin and gelatin

      G N Subba Rao K Subba Rao B Sanjiva Rao

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      A series of sorptions and desorptions of water vapour at 30° C., on gelatin, casein, egg albumin, denatured casein, denatured egg albumin have been conducted and in these systems either there is no hysteresis loop at all or the loop initially exhibited disappears on successive sorptions and desorptions.

      These results indicate that the swelling of the adsorbent on imbibing the solvating liquid is responsible for the disappearance of the hysteresis effect.

      Experiments on the sorption of ethyl alcohol at saturation pressure on the above proteins at 30°C. show that the nonsolvating liquid is either not adsorbed at all or taken up to a very small extent.

      With casein and egg albumin, the sorptive capacities for water are lower in the denatured forms of the proteins. These results indicate a decrease in hydrophilic character of the proteins on denaturation.

    • Hysteresis in sorption - XVI. Sorption of water on some indian soils and soil fractions

      Miss Sharda Gulvady K Subba Rao B Sanjiva Rao

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      Studies in sorption and desorption of water vapour at 30° C. on red laterite soil and black cotton soil and their fractions—fine sand, silt and clay have been carried out. Sorptive capacity of fine sand is found to be very small. That of silt is higher. Clay fractions have the highest sorptive capacity. Removal of organic matter lessens the sorptive capacity of the soil.

      The soils and their fractions have all yielded permanent and reproducible hysteresis loops. There is thus evidence that in soils we are dealing with rigid systems having cavities with constricted ends. The practical importance of the hysteresis effect in soils in nature is indicated.

    • Rubin numbers

      R S Subramhanya K S G Doss B Sanjiva Rao

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      The best conditions for determing rubin numbers have been worked out. The rubin number is defined as the number of milligrams of the protective colloid which when present in 10 c.c. of a 0·002% congorubin solution of pH 5·2 and electrolyte concentration of 0·02 N produces 26.5% blue colour on addition of 1 c.c. of 10% solution sodium chloride. The rubin number of a protective colloid can be accurately determined with the help of an Hellige colorimeter employing Gillespie’s technique.

    • The depolarisation of light scattered by sols

      R S Subrahmanya K S G Doss B Sanjiva Rao

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    • The chemical behaviour of sulphur compounds - Part III. Kinetics of the gaseous reaction between hydrogen sulphide and sulphur dioxide

      A R Vasudeva Murthy B Sanjiva Rao

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      Certain sulphides, in presence of a small amount of moisture were found to catalyse the reaction between hydrogen sulphide and sulphur dioxide. The kinetics of this reaction was studied in a closed system, using an all-glass, gas circulation pump.

      The partial pressure of water in the reacting system was maintained constant with the aid of a hygrostat [mixture of a hydrated salt and its anhydrous form (or lower hydrate)]. The higher the partial pressure of water, the greater was the velocity of reaction, for a given catalyst.

      Of the sulphides employed, cobalt thiomolybdate was found to be the best catalyst. Cobalt sulphide and molybdenum sulphide were less efficient. Next in order of efficiency, was silver sulphide.

      Boron trifluoride and anhydrous aluminium chloride were found to have no catalytic effect on the union between hydrogen sulphide and sulphur dioxide.

      The mechanism of the reaction could be explained on the basis of the formation of thiosulphurous acid, as the primary product.

    • Effect of salts on the determination of pH by the indicator method in presence of Igepon T

      R S Subrahmanya M R A Rao B Sanjiva Rao

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      1. In presence of Igepon T, the pH of solutions, as measured colorimetrically with thymol blue and bromophenol blue as indicators, is found to be lower in value than that obtained with the glass electrode. The value of — Δ pH (pH by the glass electrode — pH by the colorimetric method) is found to be influenced by the presence of salts like sodium chloride, sodium sulphate and calcium chloride.

      2. With thymol blue, an increase in salt concentration diminishes the value of — Δ pH, while with bromophenol blue the opposite effect is observed.

      3. With calcium chloride, the effect of salt concentration on — Δ pH is far more pronounced than with sodium chloride.

      4. The results are explained on the basis of the effect of the salts on zeta potential, in relation to the formation of complexes by the acidic and the basic forms of the indicator, with the wetting agent.

    • The ageing of bordeaux mixture

      G Narayan B Sanjiva Rao

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      Bordeaux mixture (5:5:50) prepared at room temperature (24°C.) contains a high initial concentration of copper in the aqueous phase (4 to 7 mg. copper/litre). On keeping the mixture at 24°C. the copper content of the solution decreases, and in a few days, attains a steady value of 0·47 mg. copper per litre.

      The changes in copper concentration of the aqueous phase are due to the ageing of the precipitate. Experiments conducted at 0° and at 70°C. show that an increase in temperature markedly promotes ageing.

      In the initial stages of formation of Bordeaux mixture, the aqueous phase is supersaturated with calcium sulphate, but the supersaturation does not influence in any way the ageing of the precipitated Bordeaux mixture. If, soon after its formation, the Bordeaux mixture is washed with water saturated with lime and with calcium sulphate, the rate of ageing of the solid is slightly reduced.

    • Oxidation by chloramine-T - Part I. Reaction between hydrogen sulphide and chloramine-T

      A R Vasudeva Murthy B Sanjiva Rao

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      When hydrogen sulphide is oxidised by chloramine-T, the sulphide may yield sulphur, or sulphate, or both the products. The relative proportion of the two products of oxidation depends on the pH, of the solution and on the presence of certain catalysts. At low pH, sulphate is produced in relatively high amounts, while at higher pH values, sulphur formation is greater. Presence of molybdate increases sulphate yield, while tungstate on the other hand, diminishes it. It is suggested that the primary product of oxidation of hydrogen sulphide is dihydrogen sulphoxide (H2SO) which, being analogous to hydrogen peroxide and hydrogen persulphide, is likely to be more stable at low pH values. The sulphoxide undergoes two simultaneous reactions, (a) decomposition into water and sulphur and (b) oxidation to sulphate. This accounts for the greater production of sulphate at low pH values, and of elemental sulphur in alkaline solutions.

    • Oxidation by chloramine-T - Part II. Redox potential of chloramine-T—Sulphonamide systems

      A R Vasudeva Murthy B Sanjiva Rao

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      Potentials of the chloramine-T—sulphonamide system have been found to be real redox potentials. With an increase in pH, the oxidation potential decreases. Depending on the pH of the solution, the oxidation of hydrogen sulphide by chloramine-T yields varying proportions of sulphur and sulphate. Reagents like osmic acid, sodium tungstate and sodium molybdate are also found to affect the ratio of sulphur to sulphate, formed by the oxidation of hydrogen sulphide.

      A complete explanation for the observed results cannot be based on the effect of pH on the redox potential, as these reagents do not alter the potential. The specific effect of these reagents is probably due to their influence on dihydrogen sulphoxide, the primary product of oxidation of hydrogen sulphide.

    • The oxidation of hydrogen sulphide by potassium iodate

      A R Vasudeva Murthy B Sanjiva Rao

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    • A simple method for the study of variation of boundary tension with time

      R S Subrahmanya M R A Rao B Sanjiva Rao

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      1. A new method for the determination of variation of interfacial and surface tensions with time, has been described. In this method, the advantages of the pendant drop method are combined with those of the drop weight method, thus simplifying the experimental technique.

      2. Variation of interfacial and surface tenssions with time has been investigated for congorubin solutions. The rubin solution yields at the air-liquid interface a solid film and at the solution-benzene interface a gaseous type of film.

      3. The effect of concentration of rubin on the variation of interfacial tension with time has been studied. At concentrations of rubin higher than 0·005% the fall in the interfacial tension will be large.

      4. Salts like sodium chloride and potassium iodide lower considerably the interfacial tension between rubin solution and benzene. Lowering of pH also brings about a fall in interfacial tension.

      5. The slow variation of interfacial tension has been accounted for, on the basis of changes in zeta-potential.

    • Surface chemistry of congorubin solutions

      R S Subrahmanya M R A Rao B Sanjiva Rao

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