摘要:

The Gränacher method has been investigated to discover its applicability to the synthesis of a variety of natural amino acids. The procedure has been simplified for phenylalanine and tyrosine, and extended to valine and isoleucine. An unusual product of the oximation of α-thioketo-β-(p-methoxyphenyl)propionic acid is described.

ISSN:0008-4042    

DOI:10.1139/v51-051

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Conductance measurements in the system water – nitric acid – nitrogen pentoxide have been made over a range of temperatures. The results are in accordance with the findings of Veley and Manley (12) as regards (1) the presence of a minimum in the specific conductance at about 96% by weight nitric acid (2) the existence of a negative temperature coefficient of specific conductance for solutions rich in nitric acid. As reported by Berl and Saenger (1) the specific conductance of solutions of nitrogen pentoxide in nitric acid at first increases with increasing concentration of the former, ultimately attaining a maximum and then decreasing with further increase in the nitrogen pentoxide content. Some viscosity and density data for nitric acid – nitrogen pentoxide mixtures are included.

ISSN:0008-4042    

DOI:10.1139/v51-052

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Conductance measurements have been made with ammonium nitrate in water – nitric acid – nitrogen pentoxide mixtures at various temperatures and over a wide range of concentrations. For all solutions except those rich in nitrogen pentoxide the variation of the specific conductance with the concentration of ammonium nitrate is similar to that observed for many electrolytes in a variety of solvents. With nitrogen-pentoxide-rich solvents however the specific conductance of ammonium nitrate is observed to decrease with increasing salt concentration. This is regarded as indicative of an interaction between the salt and one or more of the components of the nitric acid – nitrogen pentoxide system. The variation of conductance with temperature is normal in all cases. It is shown that ammonium nitrate confers a considerable degree of thermal stability on anhydrous nitric acid.

ISSN:0008-4042    

DOI:10.1139/v51-053

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

An independent investigation of the phase diagram for the solid–liquid system nitric, acid – acetic acid has confirmed the findings of Miskidzh'yan and Trifonov (4), namely, that a 1: 1 molecular compound exists. Conductance measurements at 0°, 25°, and 40°C. have been made for the same system. It does not appear possible to predict compound formation from the conductance measurements alone. A preliminary investigation of the liquid–vapor equilibrium for the system nitric acid – acetic acid indicates the existence of a maximum boiling azeotrope. Diacetylorthonitric acid—(CH3COO)2N(OH)3—discovered by Pictet and Genequaud (8) is, in all probability, identical with this binary azeotrope. Some molecular weight measurements tend to confirm this view.

ISSN:0008-4042    

DOI:10.1139/v51-054

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The anodic limiting current at a lead amalgam dropping electrode is shown to be proportional to the concentration of the lead in the amalgam, at constant flow rate. The original Ilkovic equation does not apply to the anodic limiting current from dropping amalgam electrodes.The anodic limiting currents with lead and cadmium amalgams have been found to agree with the 2nd approximation of the Ilkovic equation, as derived by Strehlow and Stackelberg for this process, for flow rates in the region below approximately 1.2 mgm. per sec. With flow rates greater than this, the lead amalgams gave a linear relation between the anodic limiting current divided by concentration and the mass flow rate. With cadmium amalgams no such linear relation was evident and the magnitude of the limiting current depended on the size of the drops as well as on the mass flow rates. The half wave potentials of lead and cadmium were found to depend on the flow rate of the dropping electrode.

ISSN:0008-4042    

DOI:10.1139/v51-055

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

Good yields of N-substituted ureas were obtained by reacting amines with N-nitroso-N-methylurea in aqueous solution. It has been shown that N-nitroso-N-methylurea decomposed into methylnitrosamide and isocyanic acid. Similarly, N-nitroso-N, N′-dimethylurea and amines gave rise to good yields of N-substituted-N′-methylureas.

ISSN:0008-4042    

DOI:10.1139/v51-056

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

6-Iodo-m-meconine has been prepared fromm-meconine by several steps and oxidized to 3-iodo-m-hemipinic acid. The orientation of the iodo-m-meconine is based on its conversion to 4, 5, 6-trimethoxyphthalide. The identity reported by Rây and Robinson of the bromo-m-meconine made directly by similar steps fromm-meconine with that from 2-bromoveratric acid and formaldehyde could not be confirmed. The former substance has the orientation ascribed to it by Rây and Robinson but the identity and orientation of the latter substance is left in doubt. Attempts to form a substituted diphenyl ether from dimethyl 3-iodo-m-hemipinate and the potassium salt of methyl vanillate failed.

ISSN:0008-4042    

DOI:10.1139/v51-057

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The absorption of ultraviolet light between 3000 and 4000 Å by solutions of hydrogen peroxide in water and of deuterium peroxide in heavy water has been measured at various concentrations. Both peroxides show slight but real deviations from Beer's law at high concentrations. Substitution of hydrogen by deuterium shifts the absorption continuum by about 390 cm.−1towards shorter wave lengths. This shift is of the same order as that calculated from the difference in zero-point energy of the two isotopic molecules.

ISSN:0008-4042    

DOI:10.1139/v51-058

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

A method is described for obtaining the dielectric constant and conductivity of disulphur decafluoride in both liquid and gaseous forms. The freezing point of the liquid and the molecular weight of the vapor are established as criteria of purity. All the measurements lead to the conclusion that disulphur decafluoride is non-polar. Its molar polarizations in the two forms are compared with those of other members of the sulphur fluoride and carbon fluoride homologous series as well as with hexane, benzene, and toluene.

ISSN:0008-4042    

DOI:10.1139/v51-059

出版商:NRC Research Press    

年代:1951

数据来源: NRC

摘要:

The thermal decomposition of the gas disulphur decafluoride has been studied in a metal reactor. Analytical evidence showed that the reaction proceeds according to the equation S2F10 = SF6 + SF4.The reaction was found to be largely homogeneous, as the heterogeneous reaction accounted for less than 5% of the total process. The homogeneous reaction was shown to be first order, and in the temperature range investigated the rate is given by ln k = 47.09 − 49,200/RT. A chain reaction is postulated to explain the observed rate of the reaction. The effect of nitric oxide and acetylene dichloride on the rate and products of the reaction was investigated.

ISSN:0008-4042    

DOI:10.1139/v51-060

出版商:NRC Research Press    

年代:1951

数据来源: NRC