journal article
LitStream Collection
Home
Jain, Jitendra K.; Chandalia, Sampatraj B.
doi: 10.1002/jctb.2720240302pmid: N/A
The liquid phase oxidation of acetophenone by aqueous ammonia and sulphur to phenylacetamide and/or phenylacetic acid was investigated in a stainless steel autoclave maintained under autogenous pressure. The effects of type and amount of solvent, amount of sulphur, concentration of acetophenone and ammonia, temperature and period of reaction, and the presence of impurities in commercial grade acetophenone, on the conversion and yield of phenylacetamide and/or phenylacetic acid were studied with a view to obtain the most suitable conditions for the production of phenylacetic acid. Since the product was a mixture of phenylacetamide and phenylacetic acid, hydrolysis of phenylacetamide was studied with a view to obtaining phenylacetic acid. Also, the solubility of phenylacetamide in water was determined.
Rophael, Magdy W.; Malati, Mounir A.; Barnes, Keith F.; Pulford, Richard J.
doi: 10.1002/jctb.2720240303pmid: N/A
The interaction between MnO2 (I.C.S. No. 5), in the Na+ form and 54Mn2+‐labelled solution at pH 6 involves: a rapid process assumed to be Na+/Mn2+ ion‐exchange and a slower process assumed to involve the exchange between Mn2+ ions in solution and Mn ions in a surface phase. The activation parameters ΔH# and ΔS# were found to be 52 and 83 kJ mol−1 and −130 and −63 J mol−1 for the two processes respectively. Exposing the solid to a flux of moderated neutrons had no effect on the rate of the second process. The exchange of Mn ions from the solid to the solution was demonstrated using 56Mn‐labelled solid and inactive Mn2+ solution. There was evidence of a still slower process.
Grayshan, P. H.; Mak, K. H. R.; Peters, Arnold T.
doi: 10.1002/jctb.2720240304pmid: N/A
Condensation of 3‐ and 4‐bromo‐ or nitro‐7H‐benzimidazo[2,1‐α]benz[d,e]isoquinolin‐7‐ones with 2‐aminobenzenethiol, followed by Pschorr cyclisation of the resultant product, afforded the isomer mixture of the new heterocycles benzimidazo[1,2‐b]thioxantheno[2,1,9‐d,e,f,]isoquinolin‐7‐one and benzimidazo[2,1‐a]thioxantheno[2,1,9‐d,e,f,]isoquinolin‐8‐one. Separation of these isomers and their characterisation by unambiguous synthesis is reported. Small amounts of analogous 5‐membered sulphur heterocycles were also formed by cyclisation in the β‐position of the naphthalene ring. These new heterocycles dye synthetic fibres in fluorescent orange and yellow shades, showing excellent fastness to light and sublimation. Principal mass spectra features of the compounds are given.
doi: 10.1002/jctb.2720240305pmid: N/A
Standard mixtures of gases and vapours are prepared gravimetrically with a high degree of accuracy and are used for the calibration of large quantities of multi‐component mixtures which may serve as chromatographic standards for routine analysis of gases and vapours. A dilution method is used for the preparation of very low concentrations such as fractions of a parts/106 of pentane in helium.
doi: 10.1002/jctb.2720240306pmid: N/A
Microwave heating has been shown to be a valuable method for weakening concrete prior to the separation of aggregate in the analysis of hardened concrete. Quantitative determinations were made of the strength reductions of concrete samples after microwave radiation using a 5 kW laboratory microwave generator and a 1.5 kW (later 2.5 kW) microwave oven. Aggregate separation was much easier after heating for 5 and 20 to 30 min respectively. The modulus of elasticity correlated best with subjective assessments of the ease of aggregate removal. Thirty minutes irradiation in the microwave oven reduced the modulus of elasticity to one fifth of its original value, compressive strength was reduced to 80% of the unheated value and the tensile strength to 55 to 65%. Tests with ‘miniature’ concrete showed that the reduction in impact strength was similar to the compressive strength. Conducting aggregate does not preclude the use of microwave heating although large metallic inclusions (reinforcement) should be avoided. Irradiated concretes containing an appreciable proportion of clay may yield increased amounts of soluble silica during subsequent chemical analysis. Comparison with conventional heating shows that microwave heating can produce the same strength reductions in about half the time, but the cohesiveness of the material is affected more markedly by microwave irradiation. Appendices give notes on the use of microwave heating in the analysis of concrete and some observations on the behaviour of different types of concrete heated during routine investigations.
Traetteberg, Aud; Ramachandran, V. S.
doi: 10.1002/jctb.2720240307pmid: N/A
A sequential examination of strength development in terms of microhardness was studied during paste hydration of C3S in the presence of 2 and 5% CaCl2 and at w/s ratios of 0.3 or 0.5. An attempt has been made to relate strength with microstructural features studied by means of Scanning Electron Microscopy. Generally, at earlier periods it was found that the 2% addition of CaCl2 gave the strongest material; the effect was most pronounced in the 6‐month sample of the series with 0.3 w/s. The high strength for the sample prepared at a w/s ratio of 0.3 may be related to a high CaO/SiO2 C‐S‐H‐phase, low porosity, and possibly a hydrated calcium hydroxy chloride complex. The pore size distribution was also measured. In general, the higher the porosity the lower the strengths but the relationship was not perfectly linear even on the semi‐logarithmic plot.
Rogers, John F.; Creasy, Dennis E.
doi: 10.1002/jctb.2720240308pmid: N/A
Growth measurements were made of pentaerythritol crystals in both fluidised beds and stirred suspensions. The measurements were made in both the presence and absence of the two by‐product impurities known to be normally present in the commercial material. Maximum growth rates of the order of 10−9m/s were observed with activation energies of between 100 and 200 kJ/mol depending on the sample tested. The growth rate was second‐order with respect to super‐saturation. The two main impurities were found not to greatly influence the growth rate. There was evidence that a so far undetected third impurity, which was present in only trace amounts, was responsible for the very low growth rates observed.
Showing 1 to 8 of 8 Articles