摘要:

The protonation and formation of the boron trifluoride, trichloride, and tribromide adducts of eucarvone,1, are described. Examination of the nmr and uv spectra of these systems showed that in each case the proton or Lewis acid was bonded to the carbonyl oxygen of1. From the various13C chemical shifts of the Lewis acid adducts of1, it is concluded that there is significantly less positive charge induced on the dienylic part of these molecules than is found with protonated1. All of these cationic systems undergo a ring inversion process, the barriers of which are about 1 kcal/mol greater than that reported for the comparable inversion of1.

ISSN:0008-4042    

DOI:10.1139/v77-489

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The photoisomerization of the BF3, BCl3and BBr3complexes of eucarvone (2,6,6-trimethylcyclohepta-2,4-dienone),1, have been examined. Irradiation of these zwitterions at low temperature gave, after subsequent recovery of decomplexed materials, 3,7,7-trimethylbicyclo-[4.1.0]hept-2-en-4-one,2, 2-methyl-5-isopropylphenol,3, 2-methyl-6-isopropylphenol,4, dehydrocamphor,5, and carvone,6. In the case of1•BF3and1•BCl3the initial photoproducts were shown to be the complexes of2,3,4, and5. The complexes of6were shown to arise from a secondary photoisomerization of2•BX3. It was not possible to establish the primary product distribution, obtained from1•BBr3as further photoisomerization of2•BBr3occurred even at very low degrees of conversion. The mechanisms and synthetic utility of these reactions is discussed.

ISSN:0008-4042    

DOI:10.1139/v77-490

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Co-condensation of metal atoms (Cr, Fe) with thiophenes(R = R′ = H, Me; R = H, R' = Me) at −196 °C leads to desulphurization of the thiophene. Warm-up of the iron–thiophene co-condensate in a CO atmosphere produces derivatives of tricarbonylferrole iron tricarbonyl, C4H2RR′Fe2(CO)6.13C nmr studies of these complexes show that the tricarbonyl ferrole unit is static from −95 °C to +60 °C, while the π-Fe(CO)3group exhibits fluxional behaviour. Addition of dienes or Me3P in hexane to the iron–thiophene co-condensate at −196 °C yields thermally unstable red solutions on melting.

ISSN:0008-4042    

DOI:10.1139/v77-491

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The kinetics and mechanism of exchange of deuterium between D2and water and between D2and methanol, catalyzed respectively by concentrated potassium hydroxide and potassium methoxide, has been studied between 348 and 398 K. In the D2–KOH–H2O case, the transfer of deuterium was found to be controlled by the rate of activation of the D2molecule by OH−. Rapid exchange of D+with the aqueous solution followed. From the D2–KOCH3–CH3OH studies, it was concluded that deuterium exchange depended upon the rates of both D2activation by methoxide and interaction of the solvent with the transition, or encounter, complex. The dependence of second-order rate constants on solvent activity for both systems was determined by normalization of the exchange reaction rates to unit reagent activity. Analysis of the kinetic isotope effects for each system suggested that their increase with base concentration or temperature was due to solvation effects.

ISSN:0008-4042    

DOI:10.1139/v77-492

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Bis(ethyldiazoacetate) mercury(II) is orthorhombic with the following unit cell data at 20 °C: Fdd2, a = 19.810(8), b = 14.387(5), c = 9.015(2) Å, V = 2569.3 Å3, ρ0 = 2.17(2), ρc = 2.21, Z = 8 (λ = 0.70930 Å). The structure was solved by heavy atom methods and refined to R = 2.2% for 706 reflections. The molecule has a 2-fold axis of symmetry and all thermal parameters are large in the direction of this axis; diffuse scattering was observed in the rotation photograph taken about this axis. As expected the diazoacetate portion is planar.

ISSN:0008-4042    

DOI:10.1139/v77-493

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Various lower ammines and high-energy modifications of lower ammines of the sulphates of Mn(II), Fe(II), and Zn(II) have been prepared and their heats of solution have been measured. For each of these ammine systems, the maximum difference in heat of solution, expressed in kcal/mol of heptaammine, has been found to be of the right order of magnitude to be regarded as the ligand field splitting energy for the hexaammine complex of the metal ion.

ISSN:0008-4042    

DOI:10.1139/v77-494

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A general method for the evaluation of the kinetics of the solution phase bromination of alkanes and substituted alkanes is presented. The model used considers reversible transfer reactions of the radicals formed with both hydrogen bromide and hydrogen tribromide. Cage reversal of the geminate radical – hydrogen bromide pair and reversal with hydrogen tribromide are used to rationalize the differences observed between the vapor and solution phase kinetics.The method is applied to the bromination of 1-chlorobutane.

ISSN:0008-4042    

DOI:10.1139/v77-495

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Ultrasonic velocities in deuterium oxide – water mixtures were measured at 298.15 K and 1 atm pressure using the pulse-echo-overlap method in a successive dilution mixing cell. On a mole fraction basis, the velocities show negative deviations from linearity. Excess adiabatic compressibilities derived from the results are almost zero or slightly negative.

ISSN:0008-4042    

DOI:10.1139/v77-496

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A study is presented on the chemistry of the binuclear complex [(CN)5FepzRu(NH3)5]n(n = 0 for the II–III complex andn = −1 for the II–II complex, pz = pyrazine) in solid state and in aqueous solution. Evidence for a mixed valence transition for the II–III complex was observed in the near infrared region. Based on infrared and resonance Raman spectra, a trapped-valence or class II formulation was proposed for the complex. Cyclic voltammetry indicated the occurrence of two reversible waves at 0.48 V and 0.72 V vs. NHE, which were assigned to the oxidation of the ruthenium(II) and iron(II) centers, respectively.

ISSN:0008-4042    

DOI:10.1139/v77-497

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Nitrogen and proton coupling tensors have been measured for theradical trapped in five different single crystal matrices. As all isotropic coupling constants are the same within experimental error (aN = 21.2 G,aH = 28.4 G), no measurable crystal field effect is found. In these solids the motions of the radical depend on the dimension of the trapping cage and the motions of the surrounding molecules.

ISSN:0008-4042    

DOI:10.1139/v77-498

出版商:NRC Research Press    

年代:1977

数据来源: NRC