摘要:

In the Hems synthesis of diphenyl ethers, an ortho-carbonyl offered less obstruction when held in a lactone ring than when present as an ester. Side reactions interfered with the Hems synthesis of highly hindered diphenyl ethers, and the highly hindered, highly activated ethers produced in the synthesis were easily cleaved by nucleophilic reagents, often in a few minutes at room temperature. The latter fact added a lively interest to the transformation of the ethers into other derivatives. Three of these were of special interest: (a) methyl 2-(6′-amino-4′-carbomethoxy-2′-nitrophenoxy)benzoate (VIc) which existed in remarkably stable dimorphic forms, (b) the dibenzoxazepine VIII, and (c) the quadruply orthosubstituted, asymmetrical 7-(4′-carbomethoxy -6′-laevo-menthoxyacetamino- 2′-nitrophenoxy)metameconine (IX). Attempts to isolate diastereoisomeric substances having the diphenyl ether link as an element of asymmetry failed, the classical explanation of the low configurational stability (due to bending and twisting of bonds) being superior to the quantum mechanical explanation of a tunnelling oscillation of oxygen.This paper describes the synthesis of diphenyl ethers bearing three or four groups ortho to the ethereal linkage, their conversion into asymmetrical derivatives, and our tentative conclusion that the unsymmetrical derivatives cannot be resolved into optical isomers at room temperature. The most interesting part of the paper describes the synthetic methods that must be used in the face of the very great ease of disruption of the ethereal linkage.

ISSN:0008-4042    

DOI:10.1139/v59-264

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Triacetylguanidine has been prepared and shown to undergo stepwise deacetylation in the presence of alcohol to guanidine acetate. Diacetylguanidine has been shown to have a m.p. 176–177° and not 166° as previously reported.

ISSN:0008-4042    

DOI:10.1139/v59-265

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

Iron has been electropolished over a range of voltage and current in the acetic acid–perchloric acid bath. Under optimum conditions an "atomically smooth" surface has been obtained as evidenced by marked refraction effects in the electron diffraction patterns. There is also evidence for a thin film on the electropolished surface which thickens on further exposure to air to form a preferentially oriented cubic iron oxide. Light etching in nitric acid removed the film and formed a surface which, on diffraction, gave the more normal spot pattern of iron.

ISSN:0008-4042    

DOI:10.1139/v59-266

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

D-Galacturonic acid was oxidized with decreasing ease, and in the approximate order shown, by excess of the following agents: sodium chlorite near pH 2.8 and 75°; sodium hypochlorite at pH 10–11 and 25°; chlorine dioxide, pH 1.3 or 5 at 75°; chlorine near 0° and pH 5 (slight); and hydrogen peroxide at pH 10–11 and 25° (negligible). Some uronic acid was always recovered unchanged, even from conditions that would have oxidized glucose quantitatively to gluconic acid. The only other products were mucic acid, together withDL-tartaric acid and tartronic acid presumably derived therefrom. Chlorine dioxide, however, never produced tartronic acid. Methyl-α-D-galacturonoside methyl ester yielded some galacturonic acid when exposed to alkaline hypochlorite or peroxide, and this cleavage of the glycosidic group was tentatively attributed to the oxidants rather than to the alkalinity of the systems.Anhydrous bromine degraded the silver salt of methyl-α-D-galacturonoside in poor yield to a syrup which was probablyL-arabotrihydroxyglutaric dialdehyde.

ISSN:0008-4042    

DOI:10.1139/v59-267

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The adsorption on regenerated cellulose of water at vapor pressures of 0 to 40 μ Hg has been measured by an oxygen-18 dilution technique. The results showed that cellulose may be dried to less than 0.04% moisture by evacuation at 70 °C. The adsorption isotherm was compared with that of Taylor for viscose rayon.It was also shown that oxygen-18 does not exchange between cellulose and water.

ISSN:0008-4042    

DOI:10.1139/v59-268

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The mercury-photosensitized decompositions of propane and ethane have been studied at pressures of 300 and 600 mm, at 24 °C, at very low conversions. Hydrogen was the only product identified and measured. The hydrogen yield fell rapidly at first, with increasing time of irradiation, and finally became constant. This behavior is attributed to the accumulation in the system of propylene or ethylene formed by the disproportionation of propyl or ethyl radicals, and the constant rate of hydrogen production finally achieved is thought to correspond to a steady-state concentration of the unsaturate. Previous values of the quantum yields of these decompositions were probably measured in this steady-state region, and must be corrected upwards.Relative values have been estimated for the various rate constants involved in this mechanism. There is some evidence that energy-rich radicals, formed by the addition of hydrogen atoms to the unsaturates, tend to disproportionate rather than dimerize.

ISSN:0008-4042    

DOI:10.1139/v59-269

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

By X-ray analyses it has been possible to derive the absolute configuration of (+)-des-(oxymethylene)-lycoctonine and that of (+)-demethanolaconinone. These are shown in Figs. 2 and 3.

ISSN:0008-4042    

DOI:10.1139/v59-270

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The uncatalyzed thermal decomposition of 1-hexanethiol was studied at temperature varying from 300 to 700 °C and was observed to give 42% of olefinic hydrocarbons at 600 °C. Dialkyl sulphides were also obtained at 550 °C with a maximum yield of 13.3% at 650 °C. The effect of sulphide catalyst was investigated and nickel sulphide was found to be the most effective: at low temperature (150–450 °C) dihexylsulphide was produced and at higher temperature (450–600 °C) olefinic hydrocarbons were obtained. Very little catalytic effect was observed with molybdenum and cadmium sulphides.

ISSN:0008-4042    

DOI:10.1139/v59-271

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The synthesis of 1-methyl-3,4-dihydro-β-carboline (harmalan) and of two of its derivatives by dehydration of the corresponding 1-hydroxymethyl-1,2,3,4-tetrahydro-β-carbolines is described. Harmalan was also obtained by oxidative decarboxylation of 1-methyl-1,2,3,4-tetrahydro-β-carboline-1-carboxylic acid.

ISSN:0008-4042    

DOI:10.1139/v59-272

出版商:NRC Research Press    

年代:1959

数据来源: NRC

摘要:

The structures of the ions formed by several alkyl pyrroles in hydrochloric acid are deduced from proton resonance spectra. Basicity values for three alkyl pyrroles are determined from ultraviolet spectra of their salts in buffer solutions. An attempt is made to estimate the basicity of other pyrroles from the variation of the—OD stretching frequency of methanol-din solution in the pyrroles. Variations of the free and bonded NH frequencies of alkyl pyrroles are shown to be a simple function of the positions and number of the substituents.

ISSN:0008-4042    

DOI:10.1139/v59-273

出版商:NRC Research Press    

年代:1959

数据来源: NRC