摘要:

Genisteine has been shown to be identical withl-α-isosparteine by means of a direct comparison of the physical properties of the alkaloids and their corresponding derivatives.

ISSN:0008-4042    

DOI:10.1139/v51-034

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A given current (e.g., 10−1 amp.) results generally in anonlinearhydrogen overvoltage – time relation at a copper cathode immersed inN/5 sulphuric acid. After a steady state value of the potential is reached, which may require several minutes, breaking the circuit allows the potential to fall slowly to the zero potential value. On again closing the circuit, a current of the same order as before causes, in a time of the order of seconds, alinearpotential build-up to a value equal to the steady state hydrogen overvoltage. Taking the capacitance of a uniplanar surface as 20 μf. per cm.2, the rate of the linear potential build-up permits estimation of cathode surface areas (Bowden and Rideal method). If it is now assumed that the nonlinear increase of hydrogen overvoltage with time is accompanied by deposition of a monatomic layer of hydrogen on the surface, the area occupied by this layer can be estimated. The area so calculated agrees as well as may be expected with that determined by the Bowden–Rideal method. It is concluded from these observations that the Bowden–Rideal measurement depends on the rate of charging a condenser, as distinct from the rate of increase of hydrogen overvoltage, which may be associated with deposition of a layer of hydrogen on the cathode surface. Evidence is further presented to indicate that the surface is completely covered with the layer of hydrogen at the maximum of hydrogen overvoltage, and that the Bowden–Rideal method therefore measures the true surface area of the cathode.

ISSN:0008-4042    

DOI:10.1139/v51-035

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The complex formed by mercuric nitrate with cyclohexene seems not to resemble similar argentous, cuprous, and platinous salt complexes, since it is stabilized by nitric acid while they are decomposed by acidic media. Furthermore, the cyclohexene – mercuric nitrate – nitric acid system is not stable as are the others in absence of air but decomposes to yield two equivalents of mercurous salt and one equivalent of formylcyclopentane. One or both of these products are presumed to be the material which earlier workers by implication defined as 1-hydroxy-2-nitratomercuricylohexane. It has now been found that this product could not have been formed under the reaction conditions used by these earlier workers. Finally the solubilization of cyclohexene in aqueous mercuric nitrate, on which the earlier workers based their concept of an alkene-mercurinium ion, does not have its counterpart in the solubilization of cyclohexene in aqueous mercuric acetate, since the rate of solution in the latter case is not faster than the rate of hydroxymercuration. In consequence there is no present evidence that such an ion is involved in oxymercuration of alkenes.

ISSN:0008-4042    

DOI:10.1139/v51-036

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A study has been made of the process of solidification of the alloys of tin and lead the eutectic structure of which is typically lamellar. A technique was developed in which the rate and direction of solidification were controlled. It was demonstrated that freezing takes place by the simultaneous edgewise growth of the lamellae, the thickness of which depends on the rate of freezing. It was also shown that the interface between solid and liquid at any instant is corrugated, owing to the fact that one of the phases is in advance of the other. This is attributed to the difference in thermal conductivity of the two phases. A detailed description is given of the process of eutectic solidification

ISSN:0008-4042    

DOI:10.1139/v51-037

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The condensation of monosubstituted cyanoacetic esters with hydrazine gave rise to 4-R-3-amino-5-pyrazolones. The pyrazolones prepared were those in which R = o-chlorobenzyl, β-p-methylphenoxyethyl, γ-p-methylphenoxypropyl, β-p-ethylphenoxyethyl, β-p-chlorophenoxyethyl, γ-p-chlorophenoxypropyl, γ-p-bromophenoxypropyl, orn-dodecyl.The ultraviolet absorption spectra of these pyrazolones were determined in neutral, acid, and alkaline medium.

ISSN:0008-4042    

DOI:10.1139/v51-038

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A study has been made of the polymerization of styrene in the liquid phase, initiated by acetyl radicals from the photolysis of diacetyl. The rate of consumption of monomer was proportional to the square root of the rate of light absorption; the rate of consumption of diacetyl was proportional to the first power of the rate of light absorption. The ratio of the rate constant for chain propagation to the square root of the rate constant for chain termination was found to be 3.9 × 10−3 liter1/2mole−1/2sec.−1/2at 20°C. The quantum yield of diacetyl consumption was 4.0 × 10−3. By relating the kinetic data to the observed intrinsic viscosities, the exponent of the number average molecular weight in the modified Staudinger equation was found to be 0.65. The values of the correspondingKfactors for homogeneous and heterogeneous polymers were 6.5 × 10−3and 8.2 × 10−3, respectively, when the assumption was made that chain termination was by recombination; for chain termination by disproportionation the values were 8.7 × 10−3and 12.9 × 10−3, respectively, for concentrations in base moles per liter.

ISSN:0008-4042    

DOI:10.1139/v51-039

出版商:NRC Research Press    

年代:1951

数据来源: NRC