摘要:

Crystals of difluoroboronN-methylacethydroxamate are monoclinic,a = 5.097(1),b = 10.653(2),c = 11.520(2) Å, β = 103.57(2)°,Z = 4, space groupP21/c. The structure was solved by direct methods and was refined by full-matrix least squares procedures to a finalRof 0.056 andRwof 0.077 for 988 reflections withI ≥ 3σ(I). The structure features a planar five-membered BO2CN ring. Bond lengths (corrected for libration) are: B—F, 1.374(3) and 1.381(3), O—B, 1.496(3) and 1.497(3), O—N, 1.349(2), O—C, 1.346(2), C—N, 1.298(3) and 1.458(3), and C—C, 1.468(3) Å.

ISSN:0008-4042    

DOI:10.1139/v77-001

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The type XXVIIStreptococcus pneumoniae(pneumococcus) capsular polysaccharide contains equimolar amounts ofD-glucose,D-galactose,L-rhamnose, 2-amino-2-deoxy-D-glucose, acetyl, pyruvic acid, phosphate, and choline. Structural investigations involving methylation studies and characterization of oligosaccharides obtained by three different degradations indicate the structure of the complete repeating unit to be

ISSN:0008-4042    

DOI:10.1139/v77-002

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The layered Ni(CnH2n+1NH2)2Ni(CN)4acts as a host structure for amines, yielding Ni-(CnH2n+1NH2)2Ni(CN)4,xCnH2n+1NH2(with 0 ≤ x ≤ 0.4 and 12 ≤ n ≤ 16) which are easily prepared by various procedures including solid–solid reaction. The guest can be removed and re-included; it can be replaced by aromatics. Phase transitions of the clathrate (with amines as guest) occur in the range 55–85 °C, obviously related to the transitions previously observed in the parent compound Ni(CnH2n+1NH2)2Ni(CN)4.

ISSN:0008-4042    

DOI:10.1139/v77-003

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The preparation of two tetracyclic benzenoid hydrocarbons is described using a four step synthesis involving 'aromatization' of a Diels–Alder dianhydride adduct.

ISSN:0008-4042    

DOI:10.1139/v77-004

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The temperature dependence of the equilibriawas measured forn = 1 to 5 in a pulsed electron beam mass spectrometer with a high pressure ion source. The ΔHn+1,nvalues obtained were (2,1) 15.4, (3,2) 9.1, (4,3) 8.4, (5,4) 6.7 kcal/mol. Possible structures of the clustered ions are proposed.Addition of water vapor leads to mixed cluster ions such as H+(H2S)x(H2O)y, withx + yfrom 1 to 6, observed as the ion source temperature was decreased to −100 °C. The temperature dependence of the equilibria for the exchange reactionsand the association reactionwere also measured. For all ions measured, the hydration process is energetically more favorable than the solvation by H2S.

ISSN:0008-4042    

DOI:10.1139/v77-005

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Triphenylmethylcyclopentadiene exists as a mixture of isomers, the minor and major components of which are shown to be 1-triphenylmethylcyclopentadiene (1) and 2-triphenylmethyl-cyclopentadiene (2), respectively.Direct irradiation of a mixture of1and2led to formation of 5,6,6,-triphenylbicyclo[3.1.0]hex-2-ene (3) via rearrangement of1. Acetophenone-sensitized irradiation of the same mixture gave3as well as a two component mixture of photodimers of1and/or2. Results are interpreted in terms of the di-π-methane rearrangement mechanism.

ISSN:0008-4042    

DOI:10.1139/v77-006

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A new method of forming biphenylenes substituted on one ring is described using gas-phase pyrolysis of mixtures of precursors of appropriate benzynes. The reaction of two benzynes coming from two different sources leads to the formation of the biphenylenes. The mixture of compounds is sublimed into a current of nitrogen and led into an unpacked quartz column heated externally by a furnace.The simultaneous pyrolysis of ninhydrin and tetrachlorophthalic anhydride (molar ratio, 2:1) at 800 °C gives 1,2,3,4-tetrachlorobiphenylene in a 31% yield. The pyrolysis of a mixture of phthalic anhydride and 4-methylphthalic anhydride at 850 °C leads to the formation of 2-methylbiphenylene (molar ratio, 9:1) (16%).

ISSN:0008-4042    

DOI:10.1139/v77-007

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

1H and13C nmr results for 1,2-oxathiane 2-oxide and eight derivatives are reported. It is concluded that these molecules have a high preference for chair forms with axial S=O groups, even when a sterically bulky group such as phenyl is substituted in asyn-axial orientation to the exocyclic oxygen.

ISSN:0008-4042    

DOI:10.1139/v77-008

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Bicyclo[3.2.1]oct-2-ene undergoes hydrogen–deuterium exchange through allyl and vinyl carbanionic intermediates under strongly basic conditions,tert-BuO−/tert-BuOD)at 185 °C. Only allylic exchange had been observed in previous studies withtert-BuO−/DMSO. Since the 2-tert-butoxybicyclo[3.2.1]octanes are stable under these conditions an addition–elimination sequence cannot account for exchange at C-3. The relative rates of exchange at C-2, -3, and -4, and the stereoselectivity at the allylic site were determined by2H nmr. For comparison, the rate of olefinic exchange in bicyclo[2.2.2]octene was also measured.

ISSN:0008-4042    

DOI:10.1139/v77-009

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Thermolysis of 3,5,7-triphenyl-1,2(4H)-diazepine (1) gives, besides the known 2,4,6-triphenyl-pyridine (2), 3,5,6-triphenyl-1,2(4H)-diazepine (3) and 3,5,6-triphenyl-1,2(1H)-diazepine (4) whose structures are deduced on the basis of spectroscopic and chemical evidence. Neat thermolysis of1and the related 5-(p-methoxyphenyl)-3,7-diphenyl-1,2(4H)-diazepine (24a) and 5-(p-chlorophenyl)-3,7-diphenyl-1,2(4H)-diazepine (24c) gives only the corresponding pyridine derivatives2,26a, and26cin low yields. Photolysis of1in ethanol affords the somewhat unstable 3,5,7-triphenyl-1,2-diazabicyclo[3.2.0]hepta-2,6-diene (21) which upon thermolysis undergoes cycloreversion to1and upon hydrolysis provides 3,5-diphenylpyrazole (23) and aceto-phenone. In contrast, photolysis of1as well as of24aand24c in acetone results in the formation of the pyridine (26a,26c) and pyrazole (25a,25c) derivatives respectively in low yields. Irradiation of 5-(P-dimethylaminophenyl)-3,7-diphenyl-1,2(4H)-diazepine (24d) under these conditions gives the photo-oxygenation product24e. The observed thermolysis and photolysis results of1are compared and contrasted with those reported for the closely related 4,4-dimethyl-3,7-diphenyl-1,2(4H)-diazepine (16).

ISSN:0008-4042    

DOI:10.1139/v77-010

出版商:NRC Research Press    

年代:1977

数据来源: NRC