摘要:

The far u.v. photolysis ofcis-2-butene,n-1-pentene, andcis-2-pentene was carried out in the presence of various quantities of hydrogen sulfide. We showed that in these systems, hydrogen atoms add to the double bond and are not scavenged by 5–10% hydrogen sulfide. On the other hand, alkyl radicals such as methyl, ethyl,s-butyl, ands-pentyl react with hydrogen sulfide, and the formation of the corresponding alkanes may be used to measure the absolute yields of the radical species. The same holds true for vinyl radicals. We also report some experiments published elsewhere. In particular, in the case of 1,3-butadiene, identification of the principal radicals is possible; however, measurement of absolute yields becomes more difficult.

ISSN:0008-4042    

DOI:10.1139/v72-384

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In far u.v. photochemistry, the radicals formed react with hydrogen sulfide to give, amongst others, thiyl radicals (HS•). These radicals initiate thecis–transisomerization of 2-olefins in a chain mechanism. We have tried to demonstrate that the thiyl radicals are also chain carriers. Quantum yields for the isomerization ofcistotranscompound are probably of the order of 6–7 × 103and the length of the chain, of the order of 4.7 × 103. We have also studied the radiolysis of these reactions in the liquid phase. The effect of oxygen and of conjugated di-olefins, such as 1,3-butadiene and 1,3-pentadiene is also discussed.

ISSN:0008-4042    

DOI:10.1139/v72-385

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A previously unknown alkaloid of molecular formula C15H20O2N2was isolated from the dried root bark ofEleagnusCommutata(Wolf willow or Silverberry). An X-ray analysis was undertaken to complete the structural characterization of the molecule. Columnar crystals obtained from diethyl ether have the unit cell constants,a = 13.1949(10) Å,b = 9.4525(6) Å,c = 12.1186(6) Å, β = 109°47(1)′and belong to space groupP21/c. The structure was solved using an automated symbolic addition procedure and refined by block-diagonal least-squares to weighted and unweightedRfactors of 6.25% and 4.30%, respectively. The previous structural studies were shown to be essentially correct except for the incorrect placement of the phenolic hydroxyl on C(5) of the oxindole nucleus. The correct molecular structure is implied by the systematic name given. The —OH group engages in two intermolecular hydrogen bonds with the two nitrogen atoms, but the carbonyl moiety is not involved in any such interactions.

ISSN:0008-4042    

DOI:10.1139/v72-386

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The photo-oxidation of Hg(I) by Ce(IV) has been studied at 366 mμ in aqueous perchloric acid solutions. The quantum yield depends on the concentrations of both Hg(I) and Ce(III). This dependence is different at high and low absorptions. There is a marked increase of the quantum yield with the acid concentration. It is proposed therefore that Ce4+is the species involved in the primary photochemical process.

ISSN:0008-4042    

DOI:10.1139/v72-387

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Contact angles have been measured using water drops of specified sizes, and in equilibrium with their vapor only, at their boiling point when residing on a copper surface at pressures ranging from 50–760 Torr.No appreciable change of contact angle with drop diameter was evident for sizes of 0.5 cm or more, but below this value the angles were dependent on the drop diameter, the effect of reducing pressure being to increase the dependency. The phenomenon is qualitatively explained in terms of gravity and surface roughness influences.

ISSN:0008-4042    

DOI:10.1139/v72-388

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The methylation product of 5,5-pentamethylene-2-thiohydantoin has been shown by u.v. and i.r. spectral studies to exist predominantly as 2-methylthio-4,4-pentamethylene-2-imidazolin-5-one in chloroform or cyclohexane, and as 2-methylthio-5,5-pentamethylene-2-imidazolin-4-one in water. The tautomerism of the methylation product of 5,5-pentamethylene-2,4-dithiohydantoin exhibits a similar sensitivity to solvent.

ISSN:0008-4042    

DOI:10.1139/v72-389

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The fluorine and proton n.m.r. spectra ofN-dimethylaminosulfur trifluoride andN-diethylaminosulfur trifluoride have been recorded under anhydrous conditions at −68 and +22°. Chemical shifts and coupling constants of axial and equatorial fluorines are reported.

ISSN:0008-4042    

DOI:10.1139/v72-390

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The barrier to rotation of a cyclopropyl ring around the planar carbon of a cyclopropylmethyl cation has been estimated from rates of solvolysis to be 14 kcal/mol. This value is obtained by a comparison of the rates of solvolysis of molecules which contain conformationally rigid cyclopropane rings. The results obtained compare favorably with estimates made by other methods.

ISSN:0008-4042    

DOI:10.1139/v72-391

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Carbon-13 Fourier transform n.m.r. spectra of the biopolymer, heparin, are described. The proton-decoupled spectrum corresponds to that of a molecular structure based on 12 carbon atoms, and the observed chemical shifts are shown to be consistent with a previously-proposed alternating sequence consisting of (1 → 4) linked residues of α-D-idopyranosyluronic acid 2-sulfate and 2-deoxy-2-sulfamino-α-D-glucopyranosyl 6-sulfate. Line-broadening of the C-6 signal of the latter residue indicates that spin–spin relaxation of the13C nucleus of this sulfated primary carbinol group is more effective than for the13C nuclei of the sugar rings. Among model compounds utilized for assignment of the signals from heparin is a disaccharide, 4-O-(α-L-idopyranosyluronic acid 2-sulfate)-2,5-anhydro-D-mannose 6-sulfate, prepared in 65% yield by deaminative degradation of heparin.

ISSN:0008-4042    

DOI:10.1139/v72-392

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Rhodium trichloride hydrate and rhodium carbonyl chloride react with 1,2,5-triphenylphosphole oxide (TPPO) to produce a rhodium(I) complex [RhCl(TPPO)]2, where the metal is bonded to the ligand through the π system. This complex reacts with FeCl3to produce RhCl(TPPO).FeCl3where the iron is bonded through the oxygen of the P=O group. Reactions of [RhCl(TPPO)]2with other species including nitrogen, phosphorus, and sulfur bases and carbon monoxide are described.

ISSN:0008-4042    

DOI:10.1139/v72-393

出版商:NRC Research Press    

年代:1972

数据来源: NRC