摘要:

A new alkaloid, C18H28ON2, designated flabelline, has been isolated by countercurrent distribution from the extract ofLycopodium flabelliforme. The structure and stereochemistry of flabelline have been established by its conversion to and preparation from lycopodine.

ISSN:0008-4042    

DOI:10.1139/v63-403

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Chain transfer constants of a number of phenols in the polymerization of methyl methacrylate have been determined. They are small compared with the corresponding transfer constants with styrene, a maximum value of 0.0026 being observed with pyrogallol. Three deuterated phenols do not have a measurable effect on the rate and degree of polymerization, showing that attack takes place mainly at the O—H group.The aromatic thiols investigated have transfer constants in the range 2.6 to 7.4. They cause only slight retardation of polymerization, and efficiencies of reinitiation by aromatic thiol radicals are estimated to be at least 95%. The transfer constants of meta-substituted thiols do not differ greatly from that of benzenethiol showing that inductive effects are small. A wider range of reactivities is observed with the para-substituted thiols, indicating the existence of small but significant resonance effects.

ISSN:0008-4042    

DOI:10.1139/v63-404

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Rates of methanolysis reactions ofD-xylose,D-arabinose,D-lyxose, andD-ribose have been determined. It was found that methanolysis of a pentose proceeds to equilibrium through four distinguishable, competing reactions: (1) pentose → furanosides; (2) anomerization of furanosides; (3) furanosides → pyranosides; (4) anomerization of pyranosides. The glycoside compositions at equilibrium are interpreted in terms of stabilities of each of the four glycosides from each sugar as influenced by steric and ionic effects; a system of conformational analysis of furanoside rings is presented. The free energies of reaction in anomerization of pyranosides were in excellent agreement with values calculated from previously reported interaction energies in the pyranoid ring. The relative rates of the reactions were consistent with the view that non-bonded interactions in the methyl glycosides are relieved in the transition states for their interconversions.

ISSN:0008-4042    

DOI:10.1139/v63-405

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The electronic charge distribution in substituted fulvene and pyridine derivatives is examined using the simple Hückel molecular orbital method. Parameters characterizing the electronegativity of the substituent and the carbon to which it is linked are varied in order to cover actually existing substituents.It is found that the nature of the inductive and mesomeric effects is not basically different from that in the case of benzene. The most negative sites in fulvene show a certain variation with the place of substitution. In pyridine they are the ortho and para carbons for meta substitution and the meta carbons for ortho and para substitution.

ISSN:0008-4042    

DOI:10.1139/v63-406

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The tosyl group causes interference with mixed carbonic anhydride andp-nitrophenyl ester formation in certain instances. Several protected peptide sequences, occurring in the insulin molecule, and some tosylatedp-nitrophenyl esters, have been prepared in the course of investigating this interference.

ISSN:0008-4042    

DOI:10.1139/v63-407

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

By means of the anisotropic solvent effect of benzene on the ring protons of cyclopropylamine the proton spectrum is converted to A2A2′X. Since the cross-coupling from the A2to the A2′ protons is large the spectrum does not approximate to apseudofirst-order AX4spectrum. Instead, it is one which may be described aspseudofirst-order with combination lines. The presence of the latter allows a fairly complete set of coupling constants to be derived in a simpler way than by a computer attack on the general A2B2X spectrum. Conversely, the approach developed here, when applicable, allows the derivation of reliable input parameters for a computer program. From the temperature dependence of the A2A2′X case the A2and A2′ protons can be distinguished and it is found that the protons trans to the amino group are preferentially shifted to high field by the benzene molecules.

ISSN:0008-4042    

DOI:10.1139/v63-408

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The transmission of polar effects by various groups is assessed by means of the reaction constantsρorρ″. The results are critically discussed in terms of the various polar, steric, and solvent effects. Conclusions are drawn as to the importance of the inductive and direct field effects.

ISSN:0008-4042    

DOI:10.1139/v63-409

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Salts of antipyrine (2,3-dimethyl-1-phenyl-5-pyrazolone) with halogen acids have been prepared and their infrared spectra from 4000 to 650 cm−1recorded. Stoichiometrically they are normal 1:1 salts. Identification of bands due to vibrations of the protonating hydrogen atom has been aided by replacement with deuterium atoms. It is concluded that protonation occurs at the carbonyl group from the presence of a doublet (due to correlation field splitting) at 1320 and 1220 cm−1, attributed to the in-plane hydrogen-bending mode. The OH stretching vibration gives rise to bands between 2278 and 2720 cm−1in the different salts. Out-of-plane hydrogen-bending mode absorptions are observed between 840 and 770 cm−1.More complex acids (HAsF6etc.) give the anomalous 2 base:1 acid salts, characterized by strong absorption below 1400 cm−1, which probably contain strong, possibly symmetrical, hydrogen bonds.

ISSN:0008-4042    

DOI:10.1139/v63-410

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The relative rates of reaction of a large number of ortho-alkyl phenols with styrylperoxy radicals have been measured at 65 °C. These groups have both an accelerating effect owing to their electron-donating character and a retarding effect which arises from steric factors. With two ortho-alkyl groups both the reaction rate and the overall polar contribution to the transition state decrease as the size of the alkyl groups is increased. A singleo-t-butyl group produces a small enhancement of the reaction rate over and above its polar effect but this is not observed with any other alkyl groups.

ISSN:0008-4042    

DOI:10.1139/v63-411

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The products of the reaction oft-butoxy radicals with 2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butylphenol in carbon tetrachloride have been analyzed quantitatively. There is a satisfactory agreement between the measured and calculated yields oft-butanol with both phenols. The deuterium isotope effect (kh/kd) for abstraction of the phenolic hydrogen from 2,6-di-t-butyl-4-methylphenol is about 6.4.

ISSN:0008-4042    

DOI:10.1139/v63-412

出版商:NRC Research Press    

年代:1963

数据来源: NRC