摘要:

The interactions ofN,N-dimethylpicramide (DMP) with methoxide ion in dimethylsulfoxide–methanol media have been investigated spectrophotometrically at 25.0 °C. Both the 1:1 and 2:1 σ-complexes of DMP and methoxide ion have been observed under the various reaction conditions employed. However, dimethylsulfoxide has been found to preferentially stabilize the 1:1 σ-complex relative to the 2:1 σ-complex. As a consequence, at low base concentrations in dimethylsulfoxide–methanol solutions rich in dimethylsulfoxide (i.e. 95/5, v/v, DMSO/MeOH), the 1:1 σ-complex can be formed in the absence of any 2:1 σ-complex. This observation has been used to obtain, for the first time, values of the absorption maxima and molar absorptivities at the absorption maxima of both the 1:1 and 2:1 σ-complexes.

ISSN:0008-4042    

DOI:10.1139/v80-257

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The interactions ofN-methylpicramide (NMP) with methoxide ion in dimethylsulfoxide–methanol media and with 1,4-diazabicyclooctane in dimethylsulfoxide have been investigated spectrophotometrically at 25.0 °C. Dimethylsulfoxide has been found to stabilize the conjugate base of NMP, formed via loss of hydrogen ion from the methylamino group, with respect to the anionic σ-complex generated via addition of methoxide ion to a ring carbon position. As a result, methanol–dimethylsulfoxide solutions rich in dimethylsulfoxide (i.e., 95/5, v/v, DMSO/MeOH) contain the conjugate base of NMP as the sole product of the 1:1 interaction of NMP and methoxide ion. At mole ratios of methoxide ion to NMP > 1 a second interaction results, yielding a dianion formed via addition of methoxide ion to one of the H-bearing ring carbon atoms of the conjugate base. Values of absorption maxima and molar absorptivities at the absorption maxima for the conjugate base of NMP and the dianion are reported here for the first time.

ISSN:0008-4042    

DOI:10.1139/v80-258

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A photo-electric detector is described which is capable of showing selectivity towards atomic resonance radiation. Details are given of the construction of such a device suitable for use with the mercury 253.7 nm line. A possible mechanism for the operation of the detector is considered. Its spectral selectivity is illustrated by an examination of the atomic absorption signals obtained with a partially reversed line source.

ISSN:0008-4042    

DOI:10.1139/v80-259

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Using low-temperature31P nmr, many new complexes formed between divalent cadmium (as Cd(SbF6)2) and monodentate phosphine chalcogenides in liquid SO2have been characterized. A 4:1 (L:M) complex is formed with Bu′3PS and, possibly, Bu′3PSe. 4:1 and 3:1 complexes are formed with Ph3PE, (o-C6H4Me)Ph2PE, (p-C6H4Me)3PE, and (C6H11)3PE (E = S or Se) as well as (o-C6H4Me)2PhPSe, while 4:1, 3:1 and 2:1 complexes occur for (o-C6H4Me)3PE (E = S or Se), and, probably, (o-C6H4Me)2PhPS. In addition, ail the mixed ligand complexes in the series [Cd(SeP(C6H11)3)n(SP(C6H11)3)4–n]2+, [Cd(SeP(C6H11)3)n(SP(C6H11)3)3–n]2+, and [Cd(SeP(o-C6H4Me)3)n(SP(o-C6H4Me)3)3–n]2+have been identified.Trends in the31P nmr data are discussed.

ISSN:0008-4042    

DOI:10.1139/v80-260

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The three-dimensional structure of pseudoisocytidine hydrochloride was determined by X-ray crystallography. The crystals belong to the triclinic space groupP1 and the cell dimensions area = 6.623(2),b = 8.053(2),c = 6.201(2) Å, α = 108.35(2), β = 101.36(2), γ = 93.54(2) °. Intensity data were measured with a diffractometer and the structure was solved by a combination of heavy-atom and direct methods. Least-squares refinement, which included hydrogen atoms, converged atR = 0.040. The conformation about the glycosyl bond isanti(χCC = 21.6°), the pucker of the furanose ring is C(1′)exo, and the conformation of the —CH2OH side chain isgauche–trans(t). An examination of bond lengths indicates that of the three main resonance forms of the isocytosine cation the fully conjugated one contributes more to the structure than the cross-conjugated one. Bond angles in the sugar ring reflect its rare conformation.

ISSN:0008-4042    

DOI:10.1139/v80-261

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

2-Cyclohexenone and three methylated cyclohexenones were thermolyzed at 400 °C for 20 hours to give conversions to products in the range 11 to 45%. When three monoterpenes containing the cyclohexenone moiety were thermolyzed under the same conditions the conversions were over 75%. The major products formed were alkylated benzenes, alkylated phenols, and double bond isomers of the starting enones. Mechanisms are proposed to account for these products.

ISSN:0008-4042    

DOI:10.1139/v80-262

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Dimerization of tetraacetylethylene (TAE)1has led to a spiro[furan-2(5H),2′(3′H)-furo[2,3-b]furan], whose structure was established by X-ray analysis. The trend of TAE to furan ring closure was confirmed by the reaction with ethyl vinyl ether, where the first product of the reaction, the pyran adduct8, smoothly rearranged to a furo[2,3-b]furan derivative9.

ISSN:0008-4042    

DOI:10.1139/v80-263

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

X-ray diffraction studies have revealed that K4UO2(CO3)3is isostructural with (NH4)4UO2(CO3)3; the crystal is monoclinic witha = 10.247(3),b = 9.202(2),c = 12.226(3) Å, β = 95.11(2)°,Z = 4, and space groupC2/c. Three carbonate anions are arranged in bidentate fashion in the equatorial plane of UO22+; one of these occupies aC2site and the other two occupyC1sites. All carbonates are significantly distorted fromD3hsymmetry. The binding of carbonates to uranyl is strong and thus the lattice can be considered to be composed of [UO2(CO3)3]4−anions and K+cations. The Raman and infrared spectra exhibit fewer lines than predicted for such a crystal. Tentative assignments are suggested for the more prominent bands of the constituent polyatomic species.

ISSN:0008-4042    

DOI:10.1139/v80-264

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

HeI photoelectron spectra are reported for a series of methyl-substituted monoketones and diketones based on 2-norbornanone. The effect of methyl substitution, and the inductive effect of a second carbonyl group has been studied. The diketones show a small separation between the two ketone moieties due to a through-bond interaction. Replacement with a thiocarbonyl group permits a comparison of the relative C=S and C=O interactions. The relative merits of the semi-empirical HAM/3 and CNDO/2 methods for such molecules are assessed.

ISSN:0008-4042    

DOI:10.1139/v80-265

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Aromatic dimer cations (M2+) have been generated for a series of aromatic compounds in a high pressure photoionization source. Relative third order rate constants for formation of M2+have been obtained for benzene (1.0), benzene-d6(2.7), toluene (0.8),o-xylene (1.5),p-xylene (0.7), fluorobenzene (0.3),m-fluorotoluene (0.5),m-chlorotoluene (0.7),p-chlorotoluene (0.5), ando-methoxytoluene (0.4). These values are consistent with and supplement previous data for such systems. Reagent ion monitoring has been used to determine the relative rates of reaction of both M2+and the monomer ions, M+, with a series of (mainly) aromatic compounds (X). Reaction of C6H6+is by charge transfer to compounds of lower ionization potential than C6H6. (C6H6)2+reacts only by charge transfer, if the ionization potential of X is more than 0.5 eV lower than that of benzene. When the difference is smaller, mixed dimer cations are observed which are probably formed in a switching reaction (C6H6)2+ + X → (C6H6•X)+ + C6H6.

ISSN:0008-4042    

DOI:10.1139/v80-266

出版商:NRC Research Press    

年代:1980

数据来源: NRC