摘要:

Crystals of the enone, C22H32O3, are monoclinic,P21/n,a = 15.722(4),b = 7.463(2),c = 17.213(1) Å, β = 104.67(1)°,Z = 4. The structure was solved by direct methods and was refined toR = 0.040 for 656 reflections withI/σ(I) ≥ 3.0. Crystals of thep-bromobenzoate derivative are triclinic,,a = 11.023(1),b = 11.877(1),c = 10.900(1) Ǻ, α = 90.461(8), β = 111.57(1), γ = 80.51(1)°,Z = 2. The structure was solved by Patterson and Fourier methods and refined toR = 0.032 for 2715 reflections withI/σ(I) ≥ 3.0. The X-ray studies were carried out in order to investigate a possible highly strainedtrans-fused 4 - and 5-membered ring system in a photoadduct obtained as an intermediate in the projected syntheses of stemodin and aphidicolin. The ring system was, however,cis-fused

ISSN:0008-4042    

DOI:10.1139/v83-011

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Crystals of optically active naphthidine and of binaphthyl are tetragonal,P41212 (orP43212),a = 7.945(1), 7.164(2),c = 24.264(5), 27.70(1) Å, respectively,Z = 4. The structures were solved by direct methods and refined by full-matrix least-squares techniques to respectiveR = 0.068 and 0.030 for 548 and 562 reflexions. The dihedral angles between the planes of the naphthalene residues are 87 and 102°, respectively. Bond lengths and angles are normal.

ISSN:0008-4042    

DOI:10.1139/v83-012

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The photoelectrochemical properties of phthalocyanine coated tin-oxide (SnO2) electrodes in the presence of several redox couples were investigated. The photovoltaic performances were optimized for Fe(CN)64−/3−and I2/I3−redox couples with respect to concentration, pH, counter electrode, and back contact. Under AM2 solar illumination the SnO2/x-H2Pc Fe(CN)64−/3−cells developed a photocurrent of 0.63 mA/cm2, photovoltage of 0.33 volts, fill factor of 0.25, and a power conversion efficiency of 0.07% to white light irradiation of 75 mW/cm2. The low efficiency of carrier collection was attributed to the high series resistance, surface recombination of carriers, and slow charge exchange at the counter electrode.

ISSN:0008-4042    

DOI:10.1139/v83-013

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Treatment of isophorone (8) with sodium amide and 1,2-dibromomethane gives 6,6-dimethyl-8-methylenespiro[2.5]octan-4-one (9) and 6,6,8-trimethylspiro[2.5]oct-7-en-4-one (10); similar treatment of 3-methylcyclohex-2-en-1-one (5) gives analogous spiro compounds6and7together with 8-methylenedispiro[2.1.2.3]decan-4-one (11) and 8-methyldispiro[2.1.2.3]dec-8-en-4-one (12). The spiro ketones6,7,9, and10undergo homoconjugate nucleophilic addition on being heated in morpholine with cleavage of the cyclopropane rings to give 2-[2-(4-morpholinyl)ethyl]cyclohex-2-en-1-ones. The rates of reaction are much greater for theexomethylene compounds6and9than for theirendoisomers7and10, but the rate of reaction of10is only slightly greater than that of the corresponding saturated compound, 6,6,8-trimethylspiro[2.5]octan-4-one (15). A corresponding rate differential between9and10is observed in their reactions with isophorone (8) and sodium hydride to give 2,2′-(ethanediyl)bis[3,5,5-trimethylcyclohex-2-en-1-one] (18). The acceleration in the cases of6and9relative to that of15is attributed to spiroactivation by both the carbonyl and exocyclic ethylenic groups; the much smaller effect of the endocyclic ethylenic groups in the cases of7and10is ascribed to torsional strain in the transition states for ring opening. The spiro ketones6,7,9, and10also undergo acid-catalyzed cyclopropane ring cleavage in ethanol, giving 2-(2-ethoxyethyl)cyclohex-2-en-1-ones. Again theexomethylene compounds6and9react much more rapidly than theirendoisomers7and10; this is considered to be due to factors analogous to those operative in the nucleophilic addition reactions and/or the more rapid protonation of theexomethylene compounds.

ISSN:0008-4042    

DOI:10.1139/v83-014

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Ullmann condensation using Cu or copper oxide as the reactant and using no base has been studied. Reactions of active N—H, O—H, and C—H compounds, RZH (imides, amides, amines, phenol, benzoic acid, and phenylacetylene), with mixtures of aryl halides and more than a stoichiometric amount of Cu or copper oxide (Cu2O or CuO) without addition of base lead to facile arylation of the active hydrogen compounds. In the arylation reaction Cu and copper oxides serve not only as the catalyst but also as the acceptor of halogen from aryl halide. The reactivity of phenyl halide, PhX, increases in the order PhCl < PhBr < Phl. Cu generally gives higher yields than Cu2O and CuO and, of the two copper oxides, Cu2O has the higher activity. The stronger the acidity of the active hydrogen compound (RZH), the more easily the compound is phenylated by the mixture of PhX and Cu; a roughly linear correlation betweenTi, the temperature where the phenylation starts, and the pKavalue of the active hydrogen compound has been observed. A mechanism involving initial formation of an RZ—Cu species by the reaction between RZH and Cu or copper oxide and ensuing attack of organic halide at the RZ—Cu species is proposed.

ISSN:0008-4042    

DOI:10.1139/v83-015

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The structure I clathrate hydrate of trimethylene oxide (TMO), of composition 6TMO:46H2O, has been studied by adiabatic calorimetry over the temperature range 85–270 K. A thermal anomaly, with the appearance of a classical λ-transition, was observed between about 140–170 K. This anomaly was reproducible, provided precautions were taken against supercooling. No evidence for such a transition has been observed in previous studies using dynamic relaxation techniques (dielectric and nmr relaxation). The temperature range of this anomaly is close to the melting point of a known TMO-rich eutectic, but evidence is presented which argues against interpretation of the present observations in these terms. The previous relaxation measurements indicated a transition involving mobility of the TMO guest, centred at about 100 K. In the present work, the only evidence of this transition consisted of a much worse (order of magnitude) precision in the measured heat capacities in this temperature range. Thermal equilibration is known to be extremely slow in this system. The transition observed in the present work at higher temperatures must therefore correspond to some restructuring of the water host, and this may be connected with anomalous results obtained previously for the far infrared absorptions of water in the TMO clathrate hydrate.

ISSN:0008-4042    

DOI:10.1139/v83-016

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The proton affinities of phenyl phosphine and cyclohexylphosphine were measured by determining the equilibrium constants of proton transfer equilibria with a pulsed electron beam high ion source pressure mass spectrometer. These proton affinities combined with values for methyl and phenyl phosphines and the analogous amines provide an interesting comparison of the methyl and phenyl substituent effects on the basicities of phosphine and ammonia. Methyl substitution increases the basicity of both ammonia and phosphine; however, the increase is significantly larger for the phosphine. Phenyl substitution increases the basicity of ammonia and phosphine and the increase for phosphine is very much larger. Calculations at the STO-3G, 4-31G, STO-3G*, and 4-31G* (* withdorbitals) for PH3, MePH2, PhPH2, the protonated species, and the nitrogen analogues predict proton transfer reaction energies in good agreement with the experimental results. A shortening of the C—P bond is predicted for protonation of MePH2and particularly PhPH2, while a lengthening of the C—N bond is predicted for the corresponding nitrogen compounds. The much stronger increase in proton affinity of the phosphines caused by phenyl substitution is due to the stabilization of the phenyl phosphonium ion by π donation from the phenyl group to the empty orbitals of phosphorus in thegroup; in contrast, in the amines, it is the free base aniline which is stabilized by conjugation of the nitrogen lone pair with the aromatic ring. This stabilization of the free base is less important in phenyl phosphine. The participating empty orbitals of phosphorus in the conjugation of phenyl within phenyl phosphonium are mostly π* with some -πdparticipation. The stabilization of the aniline free base contributes considerably more than the conjugation in the phosphonium ion, to the phenyl substituent difference for the amines and phosphines. The factors involved in the bigger substituent effect of methyl in the phosphines are somewhat similar to those for phenyl: stabilization of the methyl amine by conjugation of the nitrogen lone pair with empty orbitals of CH3and stabilization of theby hyperconjugation. An alternate description can be given in terms of hybridization changes.

ISSN:0008-4042    

DOI:10.1139/v83-017

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The kinetics of the oxidation of a nickel(II) oxime complex by a series of iron(III) phenanthroline and bipyridine cations, Fe(LL)33+, have been investigated. The overall reactionis considered to take place via two one-electron steps, the first (rate-determining) process yielding Ni(III)(H2L)3+being followed by very rapid oxidation to the nickel(IV) product. The second order rate constants at 25 °C in 0.50 Mp-toluenesulphonic acid are: Fe(dmbpy)33+, 1.32 × 103 M−1s−1; Fe(dmphen)33+, 3.73 × 103 M−1s−1; Fe(bpy)33+, 3.20 × 104 M−1s−1; Fe(mphen)33+, 6.83 × 104 M−1s−1; Fe(phen)33+, 9.16 × 104 M−1s−1; and Fe(cphen)33+, 5.6 × 105 M−1s−1. The reactions are outer-sphere in character. The rate of the corresponding cross reaction of nickel(II) species with Ru(bipy)33+(k12 = 1.1 × 106 M−1s−1) has also been measured. Activation parameters have been incorporated in a Marcus theory correlation to yield information (k11 ~ 3 × 103 M−1s−1) for the NiII(H2L)2+/NiIII(H2L)3+electron exchange reaction. This value is compared with exchange parameters for NiII/NiIIItetraaza-macrocycle and other similar systems.

ISSN:0008-4042    

DOI:10.1139/v83-018

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

The conformational properties of 2-alkyl (Me, Et, i-Pr, andt-Bu) and 2-phenyl derivatives of 1,3-dioxa-5,6-benzocycloheptene (1) were studied by13C dnmr. Analysis of slow exchange spectra at 100.6 MHz indicates that all derivatives excepttert-butyl exist in an equilibrium of chair (major) and twist-boat (minor) conformations. Substituent effects on the position of the equilibrium are rationalized in terms of steric effects.

ISSN:0008-4042    

DOI:10.1139/v83-019

出版商:NRC Research Press    

年代:1983

数据来源: NRC

摘要:

Kinetic data are reported for the solvolysis of 1-methyl cyclopentyl chloride in a 50% by volume ethanol+ water mixture. These data are combined with kinetic data for solvolysis of three deuterated analogues; 1-methyl-d3cyclopentyl chloride, 1-methyl-2,2,5,5-d4cyclopentyl chloride, and 1-methyl-d3-2,2,5,5-d4cyclopentyl chloride, being thed3d4, andd7, derivatives respectively. The kinetic data are used to calculate the kinetic deuterium isotope effect,kH/kD. For these systems, thed7-isotope effect is close to the product of thed3andd4effects.

ISSN:0008-4042    

DOI:10.1139/v83-020

出版商:NRC Research Press    

年代:1983

数据来源: NRC