摘要:

Nitric oxide (120 Torr) strongly suppressed the thermal decomposition of NaN3at 350 °C. A relatively slow and complex reaction occurred instead, yielding N2, N2O, NaNO2, and Na2O. Isotopic experiments revealed that most of the N2(60–80%) came from the azide alone, some from NO alone (10–28%), and a small proportion (5–8%) was mixed, with one atom derived from each reagent. Nitrous oxide initially was derived entirely from NO.Hydrogen (12–75 Torr) also suppressed the normal azide decomposition at 350 °C. In its place, a rapid reaction occurred, consuming H2and NaN3and producing N2, NH3, Na, and probably NaNH2.Both systems were complex and probably best described as concerted reactions between the azide and the added gas rather than reactions of NO or H2with transient nitrogen species formed in the thermal decomposition of the azide.

ISSN:0008-4042    

DOI:10.1139/v72-121

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Radicals formed by γ-irradiation of propylene carbonate (PC) glasses at 77 °K were studied by e.s.r. and optical spectroscopy. Trapped electrons were identified by their narrow (ΔHms = 4.5 G) Gaussian e.s.r. line atg = 2.0028 which was completely resolved from the radical spectrum. The trapped electrons were unstable at 77 °K. They decayed fairly rapidly via a process exhibiting non-homogeneous kinetics believed to be reaction with positive ions. The temperature dependence of the e.s.r. spectra of the other radicals formed is discussed although conclusive assignment of the lines could not be made.Ultraviolet photolysis of the radicals in the irradiated PC glasses produced new species identified as HCO, CO3−, and CH3by their characteristic e.s.r. spectra. In addition, a complex optical absorption band in the 500–750 nm region was assigned to a combination of the absorption bands of the CO3−radical anion and the HCO radical.

ISSN:0008-4042    

DOI:10.1139/v72-122

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Two different crystalline models of cellulose have received attention from crystallographers: the "straight chain" model of Meyer and Misch and the "bent chain" model of P. H. Hermans. We have examined these models and have given a mathematical interpretation of each in terms of the conformational anglesand ψ and the glycosidic angle τ. For a given geometry of the glucose residue, the "straight chain" corresponds to a unique value of τ; for a value of τ greater than the unique value, two "bent chains" are possible, one allowing an intramolecular hydrogen bond (O-3 … O-5′) and the other not. It is suggested that the former only be referred to as the Hermans conformation.

ISSN:0008-4042    

DOI:10.1139/v72-123

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Thirteen new bi- or polycyclic vicinal exocyclic dimethylene hydrocarbons (10–22) have been synthesized and some of their spectral properties recorded. The generally most useful synthetic route to such compounds utilizes base-catalyzed double elimination fromtrans-1,2-bis(hydroxymethyl)alkylp-toluenesulfonates as the final step in the production of the conjugated diene.

ISSN:0008-4042    

DOI:10.1139/v72-124

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The synthesis ofcisandtrans1,3-dimethylpiperidin-4-ols and derived acetate, benzilate, and diphenylacetate esters is described. Configurations and preferred conformations of these derivatives are assigned on the basis of 4-methine and 4-hydroxyl p.m.r. characteristics. Conformational studies of esters of 1-methyl-piperidin-3-ol and isomeric 3-tropanols are also described. Epimeric conjugate acids are well defined in 3-acetoxy-1-methylpiperidine hydrochloride as solute in CDCl3.

ISSN:0008-4042    

DOI:10.1139/v72-125

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The reactions of 2-lithio-1,3-dithiane with both 2α,3α- and 2β,3β-oxiranyl-5α-cholestane have been used to prepare both epimers of 2-methyl-3-oxo- and 3-methyl-2-oxo-5α-cholestane. The results obtained illustrate the potential of the dithiane-epoxide route as an attractive and versatile general procedure for the stereospecific introduction of substituents into alicyclic compounds. Furthermore, since for six-membered ring compounds the epoxide ring is opened in atrans-diaxial manner, the substituent is introduced into the thermodynamically less stable orientation. Subsequent isomerization to the preferred equatorial isomer is thus possible and accordingly, both epimers are obtainable from the same synthetic sequence.

ISSN:0008-4042    

DOI:10.1139/v72-126

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

An evaluation is made of the extent to which13C chemical shifts of diastereoisomeric cyclohexane derivatives and pyranoses are related to electron density. Values of the latter for carbon atoms in cyclohexane, methylcyclohexanes, cyclohexanols, andD-glucose are calculated using the Extended Hückel Theory (EHT), with and without iteration, and the Del Re theory. It is shown that when electronegativities of all of the atoms are similar then the theories do not give electron densities which correlate with the 13C chemical shifts; when a strongly electronegative atom, such as oxygen, is present, the electron density differences are greater than the inaccuracy in the calculated individual densities and a fair correlation with13C chemical shifts is obtained. Iteration is shown to give lower carbon electron densities and a better correlation.

ISSN:0008-4042    

DOI:10.1139/v72-127

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The mass spectra and fragmentation patterns of several tropolones and tropolone methyl ethers are reported. Deuteration studies confirmed that elimination of a formyl radical from 2-methoxytropone upon electron impact involves a specific rearrangement of the methoxyl group but sequential loss of carbon monoxide and a hydrogen radical from the ring are competing reactions. They also showed that in a dimethyl ether of anhydrosepedonin elimination of a formyl radical is completely suppressed. In the methyl ether of stipatatonic acid elimination of carbon monoxide is followed by expulsion of carbon dioxide with no loss of 29 mass units. The mass spectrum of [8-13C]-anhydrosepedonin as well as the energy spectrum for sepedonin have been investigated. These results not only provide a plausible account of the fragmentation of tropolones following electron impact but also illustrate the effect of product ion stability in determining which among a number of alternative modes of fragmentation will be more probable.

ISSN:0008-4042    

DOI:10.1139/v72-128

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Where A designates the dinegative 3-ketoglutarate ion and L indicates a trinegative species (likely the enolate ion), the following compounds have been obtained: Na2A, NaCuL.XH2O, MgA.XH2O, MnA.XH2O, CoA.XH2O, NiA.XH2O. Hydration numbers are uncertain. Stoichiometry of Cu(II) and Zn(II) compounds could not be established. Structures have been assigned on the basis of the infrared spectra. Na2A appears to be a simple ionic carboxylate. MgA, MnA, CoA, and NiA are assigned a similar structure, with unidentate carboxylate coordination and hydrogen-bonded coordination between the metal and the second carboxylate oxygen (through water). NaCuL is assigned a metal-bridged polymer structure. There is not significant metal interaction with the carbonyl oxygen in any of the proposed structures.

ISSN:0008-4042    

DOI:10.1139/v72-129

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Data are presented for the saturation solubility and partial molal volume of iodine in a mixed benzene–cyclohexane solvent and for the saturation solubility of stannic iodide in the same solvent mixture. A successful interpretation of these data in terms of solubility parameter theory is possible if we define an effective volume fraction term. This term reflects the immediate solvent environment of the solute molecule with the preferential solvation of the solute by one of the solvent molecules. Data for iodine in a mixed carbon tetrachloride–benzene solvent mixture and for iodine in a carbon tetrachloride–perfluoroheptane mixture are also interpreted in terms of the proposed theory.

ISSN:0008-4042    

DOI:10.1139/v72-130

出版商:NRC Research Press    

年代:1972

数据来源: NRC