摘要:

The specific rate constants for the formation of the 1:1 1,3,5-trinitrobenzene – cyanide ion σ-complex in ethanol,n-propanol, isopropanol, andt-butanol are 442 ± 14,932 ± 30, 2.45 ± 0.10 × 103and 1.06 ± 0.05 × 105 M−1s−1, respectively. A plot of logkvs. Dimroth's solvent parameterEtis linear with slope −0.25. The kinetics of the reactions of cyanide ion and 1,3,5-trinitrobenzene in ethanol andn-propanol are complicated by alcoholysis of cyanide ion which yields the corresponding alkoxide ion and the 1:1 1,3,5-trinitrobenzene–alkoxide ion σ-complex.

ISSN:0008-4042    

DOI:10.1139/v74-001

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Equilibrium constants for the formation of 1:1 cyanide ion σ-complexes with 1,3,5-trinitrobenzene, 2,4,6-trinitroanisole, and 2,4,6-trinitrotoluene have been determined spectrophotometrically over a range of temperatures. Standard enthalpy (ΔH0) and entropy (ΔS0) changes associated with each reaction have been evaluated. The kinetics of formation of the σ-complexes have been investigated by means of a stopped-flow technique and the activation parameters characterizing the formation of each complex have been determined. Evidence is presented which indicates the cyanide ion – 2,4,6-trinitroanisole σ-complex formed in isopropanol contains the cyanide ion bonded exclusively at the C-3 position.

ISSN:0008-4042    

DOI:10.1139/v74-002

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Picryl chloride reacts rapidly with methoxide ion in methanol to form a σ-complex containing methoxide ion attached to the C-3 position of the picryl chloride. Thermodynamic and kinetic parameters characterizing this reaction are presented and compared with corresponding parameters for the analogous reaction of methoxide ion and 2,4,6-trinitroanisole in methanol. Details concerning the much slower formation of the σ-complex containing methoxide ion added to the C-1 position of picryl chloride are also presented.

ISSN:0008-4042    

DOI:10.1139/v74-003

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The kinetics of the reactions between sulfite ion and picramide,N-methylpicramide, andN,N-dimethylpicramide, to form 1:1 σ-complexes in aqueous solutions of constant ionic strength 0.14 M, have been investigated using a stopped-flow spectrophotometer. Specific rate constants for the formation and decomposition of these three complexes at 25.0 °C are 5.7 ± 0.2 × 104M−1s−1and 7 ± 1 s−1, 1.4 ± 0.1 × 104M−1s−1and 0.20 ± 0.02 s−1, and 4.1 ± 0.2 × 103M−1s−1and 0.14 ± 0.04 s−1, respectively. Enthalpies and entropies of activation characterizing the formation of the 1:1 σ-complexes have been determined. Equilibrium constants, determined spectrophotometrically at a number of temperatures, have been used to calculate the enthalpy (ΔH0) and entropy (ΔS0) changes associated with 1:1 and 2:1 σ-complex formation. These values are compared with corresponding ones for complex formation of sulfite ion with 1,3,5-trinitrobenzene and 2,4,6-trinitrobenzaldehyde. The extent of solvation of the σ-complexes is considered to play a primary role in determining the observed trends in the enthalpies and entropies of reaction.

ISSN:0008-4042    

DOI:10.1139/v74-004

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The vacuum u.v. photolysis of trimethylethylene (2-methyl-2-butene) was carried out in a static system using rare gas resonance lamps: xenon (147.0 nm) and krypton (123.6 nm). The main hydrocarbon products were isoprene, 1,3-butadiene, propyne, allène, ethylene, and other minor products. Identification and measurements of the yields of hydrogen atoms, methyl, and ethyl radicals were carried out quantitatively by the use of radical–radical reactions. Because of the high yield of isoprene, the effect of conversion was studied. At a high conversion (i.e. 0.1%) the isoprene quantum yield decreases. Hydrogen atoms add mainly to the secondary carbon of the monomer (≥90%). The Δ(CH3,tert-C5H11) value was calculated to be 1.32 ± 0.14. With the krypton line (10.0 eV) no evidence was found for the participation of ionic reactions in the formation of the measured products except for the formation of 2-methyl-1-butene in a low yield. At this wavelength the ion quantum yield is 0.224 ± 0.005.

ISSN:0008-4042    

DOI:10.1139/v74-005

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Comparisons of1H chemical shifts and charge densities (determined by CNDO/2 MO calculations) for 4-substituted derivatives of styrene, toluene, benzylchloride, andN,N,N-trimethylphenylammonium ion indicate that the chemical shifts primarily reflect intramolecular electronic effects. These effects are reflected by correlations of1H chemical shifts with theFandRreactivity parameters of Swain and Lupton. It is concluded that it is valid to correlate substituent-induced chemical shifts for aromatic derivatives with divided reactivity parameters provided that (1) chemical shifts are measured at infinite dilution in a non-polar medium and (2) at least ten derivatives of each family are investigated.Calculations for 4-substituted toluenes indicate that there will be a small conformational dependence for substituent-induced benzylic proton chemical shifts.

ISSN:0008-4042    

DOI:10.1139/v74-006

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Crystals of Co7.0As3.6O16(1.8 × 3.84 CoO.As2O5) are orthorhombic with unit cell parametersa = 10.526(5),b = 5.985(2), andc = 4.871(2) Å. The space group isPnmawithZ = 1 and, except for fractionally occupied cation sites, the crystals have a structure closely related to that of the mineral olivine. The structure was refined by full-matrix least-squares with isotropic thermal parameters, using 1175 independent reflections measured with MoKα radiation, to a finalRvalue of 0.075. The composition was determined by site population analysis. The structure is based upon a hexagonally close-packed arrangement of oxygen layers with As in tetrahedrally and Co in octahedrally coordinated interstices. The mean As—O bond length is 1.676 Å and the mean Co—O bond lengths are 2.139 Å for the site withmsymmetry and 2.174 Å for the site showing inversion symmetry. These bond lengths are uncorrected for the effects of fractional occupancy of some of the cation sites.

ISSN:0008-4042    

DOI:10.1139/v74-007

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Addition of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro-hexopyranosid-3-ulose (1) to acetonitrile in liquid ammonia at −50 to −60° in the presence of lithium amide gave, in high yield, crystalline methyl 4,6-O-benzylidene-3-C-cyanomethyl-2-deoxy-α-D-arabino-hexopyranoside (2) exclusively. The proof of structure2is described. Debenzylidenation of2afforded the branched-chain cyano glycoside3. Compound3was converted into its 3,4,6-tri-O-acetate (8) and 4,6-di-O-p-nitrobenzoate (9) derivatives. Catalytic hydrogenation of3over rhodium on alumina yielded methyl 3-C-2′-aminoethyl-2-deoxy-α-D-arabino-hexopyranoside which was characterized as itsN-2,4-dinitrophenyl derivative (7).

ISSN:0008-4042    

DOI:10.1139/v74-008

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A series ofN-substituted 3-amino-2-cyclohexen-1-ones and 3-amino-5,5-dimethyl-2-cyclohexen-1-ones (1–9) has been prepared. Halogenation of these compounds with bromine, NBS, cyanogen bromide, and iodine is described. The tendency of enaminoketones to form salts of the corresponding enol-ketimine form was observed and structures of the salts are supported by their p.m.r. and i.r. properties. The reaction of 3-benzylamino-2-bromo-5,5-dimethyl-2-cyclohexen-1-one with concentrated sulfuric acid effected debenzylation. Treatment of 3-benzylamino-2-iodo-5,5-dimethyl-2-cyclohexen-1-one with dibenzoyl peroxide gave 8,8a-dihydro-5-iodo-8,8-dimethyl-2,3-diphenyl-4H-1,4-benzoxazine-6,7-diol. The above secondary enaminoketones1–9were shown to react with phenyl isocyanates, phenyl isothiocyanate. and methyl isothiocyanate under fusion conditions to yield substituted 2-amino-6-oxo-1-cyclo-hexene-1-carboxamides and corresponding thiocarboxamides. 2-Benzylamino-6-oxo-N-phenyl-1-cyclohexene-1-carboxamide and its 5,5-dimethyl analog were found to undergo facile transamination in position 2, when heated with a primary amine. This reaction is of synthetic utility for the preparation of biologically active derivatives with a basically substituted side chain. Addition of 4-methylamino-3-pentene-2-one to phenyl isocyanate afforded 2-acetyl-3-methylaminoisocrotonanilide; the spectroscopic properties of this product are discussed.

ISSN:0008-4042    

DOI:10.1139/v74-009

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The addition of 14 dimethyl aryl- and alkyldiazomethylphosphonates, RC(N2)P(O)(OCH3)2, to norbornadiene has been studied and the stereochemistry of the resultingexo-Δ1-pyrazolines determined by n.m.r. Theanti/synratio of the cycloadducts is discussed in terms of steric and electronic factors. For alkyldiazomethylphosphonates steric factors are the dominant ones, while with aryldiazomethylphos-phonates electronic factors seem to be of importance.

ISSN:0008-4042    

DOI:10.1139/v74-010

出版商:NRC Research Press    

年代:1974

数据来源: NRC