摘要:

A study has been made of some factors affecting the migration or elimination of halogen in the Claisen rearrangement of allyl 2,6-dihalophenyl ethers.In the thermal rearrangement of allyl 2,6-dichlorophenyl ether, carried out in a number of solvents of different dielectric constant, halogen migration proceeds somewhat better in highly polar solvents. However, a competitive reduction to the monohalogenated allylphenol occurs in the presence of oxidizable solvents and/or products. The reaction is also complicated by the catalytic effects of certain solvents and the phenolic products, which give results similar to those obtained with Lewis acids. Stannous chloride acts as a Lewis acid and catalyzes the rearrangement of allyl 2,6-dichlorophenyl ether with simultaneous halogen rearrangement. As well, a competitive reductive removal of the halogen takes place. Results from the rearrangement of allyl 2,6-dibromophenyl ether with zinc chloride and of allyl 2,6-dichlorophenyl ether with zinc bromide, as well as those from the stannous chloride reactions indicate that the halogenmigrationtakes place not only by an allylic shift but also via a competitive halogensubstitutionprobably occurring by an Sn2′ pathway possibly assisted by a zinc halide bridge mechanism and/or an ionic species such as.

ISSN:0008-4042    

DOI:10.1139/v63-430

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The nitromethane cyclization ofL′-methoxy-diglycolic aldehyde was shown to furnish methyl 3-nitro-3-deoxy-α-L-arabinopyranoside and methyl 3-nitro-3-deoxy-β-D-arabino-pyranoside as coproducts of the previously obtained -β-D-riboisomer. As expected, the enantiomorphic dialdehyde,D′-methoxy-diglycolic aldehyde, afforded the corresponding α-D- and β-L-arabinoderivatives in addition to the β-L-riboisomer. Catalytic hydrogenation of the four new nitroglycosides gave the corresponding aminoglycoside hydrochlorides. The 3-amino-3-deoxy-D- andL-arabinose hydrochlorides were obtained from their glycosides by hydrolysis and crystallized as mutarotating β-forms.The spontaneous epimerisation, in aqueous solution, ofaci-nitropentoside sodium salts was investigated.

ISSN:0008-4042    

DOI:10.1139/v63-431

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The reaction ofN,N-dimethylaniline (A) with benzoyl peroxide (P) has been shown to exhibit complex kinetics. The observed rates of peroxide decomposition between 0° and 25 °C could be described by the relation−d[P]/dt = ka[A][P]+kb[A]1/2[P]3/2. An unstable Würster salt of tetramethylbenzidine was shown to be one of the main products of the reaction, and a mechanism has been postulated which is consistent with the observed kinetics, involving tetramethylbenzidine as a reaction intermediate.

ISSN:0008-4042    

DOI:10.1139/v63-432

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

When benzoyl peroxide was used to initiate the reaction of oxygen withN,N-dimethylaniline, a chain reaction was shown to occur, resulting in an almost quantitative yield of hydrogen peroxide. The reaction was inhibited by mercaptan and benzoquinone, but not by hydroquinone, and was shown to be autoinhibited as well. The rate of oxidation was observed to be much greater in polar solvents, such as acetonitrile or methanol, than in non-polar solvents such as toluene and benzene. Diethyl- and dipropyl-aniline exhibited no chain characteristics under similar conditions, whereas dimethylbenzylamine and dimethyldodecylamine did not react at all.A mechanism has been postulated involving both semiquinone and peroxide chain carriers which is consistent with all of these observations. From an analysis of the oxidation rates in the presence and absence of mercaptan inhibition, the appropriate rate constants have been determined.

ISSN:0008-4042    

DOI:10.1139/v63-433

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The thermal reactions of ethylene oxide in the presence of an excess of propylene have been studied as a function of pressure and it has been found that there are two sets of products, acetaldehyde and free radicals, presumably methyl and formyl. These products are believed to arise from an excited acetaldehyde intermediate. Some evidence has been obtained for the occurrence of a surface-catalyzed rearrangement to acetaldehyde but the free radical products are uninfluenced by surface.

ISSN:0008-4042    

DOI:10.1139/v63-434

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A number of N-bis(2-chloroethyl)amines and three N-bis(2-iodoethyl)benzylamines have been prepared for cancer chemotherapy studies. The chloro-nitrogen mustards were readily obtained by aluminum chloride – lithium aluminum hydride reduction of the corresponding N-bis(2-chloroethyl)amides. A convenient procedure for converting N-bis(2-chloroethyl)-benzylamine hydrochlorides to N-bis(2-iodoethyl)benzylamine hydroiodides, employing sodium iodide, was also developed.

ISSN:0008-4042    

DOI:10.1139/v63-435

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The chemical shifts of protons and carbon-13 nuclei in aliphatic and aromatic halogen compounds are considered on the basis of inductive, magnetic anisotropy, and intramolecular dispersion effects. It is suggested that a model based on all three effects is more consistent with experiment than a model based on the first two effects only. The dispersion effects in general cause a low-field shift and seem to outweigh magnetic anisotropy effects in some cases.

ISSN:0008-4042    

DOI:10.1139/v63-436

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

α-Trimethylsilyl acrylic acid and its methyl ester were prepared in good yield starting from 1,2-dibromoethyltrimethylsilane. These monomers were polymerized with difficulty by free radicals to viscous polymers, but gave solid copolymers with styrene. The methyl ester was also a weak monomer in anionic polymerization. This non-reactivity is due to the steric effect of the α-trimethylsilyl group adjacent to the double bond.

ISSN:0008-4042    

DOI:10.1139/v63-437

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Crystals of bis(diphenylarsenic) oxide are monoclinic, with four molecules in a unit cell of dimensionsa = 11.48,b = 30.2,c = 5.97 Å, β = 93.8°, space groupP21/n. The structure has been determined from projections along theaandcaxes, using Fourier and difference syntheses. The As—O—As angle is 137°, the increase from the normal oxygen valency angle probably being a result ofpπ—dπbonding involving arsenic 4dorbitals. The As—O distance is 1.67 Å, and all the other bond lengths and angles are normal. The orientations of the substituent phenyl groups have been determined.

ISSN:0008-4042    

DOI:10.1139/v63-438

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A linear correlation between the bond orders and stretching force constants of bonds, which appears to have general application, is derived on the basis of a potential energy function previously used by Pauling in a correlation of C—C bond length with bond order. The relationship is shown to be consistent with predicted bond orders and experimentally determined force constants of C—C, C—O, N—N, and N—O bonds.The possible effects of anharmonicity and resonance energy on the force constant and equilibrium C—C bond distance are considered for the case of the benzene molecule, and it is concluded that the best agreement with experiment is obtained if we postulate a low degree of anharmonicity and allow for the change of resonance energy with bond distance.

ISSN:0008-4042    

DOI:10.1139/v63-439

出版商:NRC Research Press    

年代:1963

数据来源: NRC