摘要:

The azotization of 1,4-diaminoanthraquinone (1) byn-amyl nitrite in glacial acetic was reinvestigated. The structure of a red-brown precipitate, which was previously identified as anthraquinone-1,4-tetrazonium dichloride (3) by Schaarschmidt, was found to be incorrect. In this work, we have identified the red-brown solid as 4-aminoanthraquinone-1-diazonium chloride (2), a diazotized product of1. The yield of2was 80%. The tetrazonium dichloride3was actually formed in minute quantity and is soluble in acetic acid. The tetrazonium product of1can be isolated as tetrafluoroborate salt4in 3.4% yield by adding fluoboric acid into the acetic acid solution. The structure4was confirmed by IR and cross-polarization magic angle spinning13C NMR spectroscopy. Further investigations showed that1can be quantitatively tetrazotized by nitrosylsulfuric acid in 78% sulfuric acid. The tetrazonium product was isolated as4in 74% yield.Keywords: 1,4-diaminoanthraquinone, diazotization, tetrazotization, azo pigments.

ISSN:0008-4042    

DOI:10.1139/v91-176

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

In many applications of NMR spectroscopy to chemistry, quantitation play s a key role. This paper argues that peak heights not onlycanbe used for quantitative work in NMR but that for careful work theyshouldbe used. Integrals are accurate, but because they depend on many subjective factors, their precision is suspect. Peak heights are very reproducible on modern spectrometers and so, given this precision, the accuracy can be obtained as well by using calibration methods. An example of the application of these methods is given in the case of a13C labelling experiment that elucidates a photochemical transformation.Keywords: NMR, labelling, quantitation, peak heights, integrals.

ISSN:0008-4042    

DOI:10.1139/v91-177

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

Two rigid nitrobenzene derivatives, 5-nitro-1,2,3,4-tetrahydro-1,4-methanonaphthalene (6), and 5-nitro-1,2,3,4-tetra-hydro-1,4-ethanonaphthalene (7), have been synthesized and studied by picosecond flash absorption spectroscopy, steady-state irradiation, and MMX molecular mechanics calculations. Transients with lifetimes of 770 and 410 ps have been detected and assigned to the excited triplet states of6and7, respectively. Consistent with prediction, theo-quinonoid intermediate is not detected in the time domain between the laser excitation and the end of decay of the triplet state. Intramolecular abstraction of the bridgehead benzylic hydrogen by the cited triplet state proceeds with relative rates of 1:125 for6and7, respectively. Since structural constraints prohibit the formation of an orthoquinonoid intermediate in these systems, formation of the usual nitrosoalcohol13represents the first substantiation of the biradical route to product (3′ → 4, Scheme 1). Absorption of the intermediate triplet biradical resulting from hydrogen abstraction by the triplet excited state was not observed, and is therefore believed to be either very weak in the 400–700 nm region, or located outside the detection region. The kinetic results together with structural parameters determined by molecular mechanics show good correlation between structure and reactivity. Hydrogen atom transfer can proceed at up to 53° deviation from linearity of the C—H—O nuclei, with transfer rates decreasing sharply as thedistance increases from 1.3 to 1.6 Å. It is suggested that the conditions of the reaction from the excited triplet state meet those required for a hydrogen tunneling mechanism.Keywords:o-nitrotoluene photorearrangement, mechanism of;o-nitrobenzyl systems, mechanism of photorearrangement;distance, influence of, in hydrogen abstraction mechanism; picosecond flash absorption spectroscopy study ofo-nitrobenzyl photorearrangement; radical pathway to product ino-nitrotoluene photorearrangement.

ISSN:0008-4042    

DOI:10.1139/v91-178

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The synthesis of cyclic imines2, β-enaminones6, and β-enaminodiketones7is described. Regio- and stereospecific thermolysis of β-enaminoesters4with boric acid permit these preparations in generally good yields.Keywords: boric acid, cyclic β-enaminoesters, decarboxylation, cyclic imines, cyclic β-enaminones.

ISSN:0008-4042    

DOI:10.1139/v91-179

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The1H and13C NMR spectra of chromotropic acid (CTA) (4,5-dihydroxy-2,7-naphthalenedisulphonic acid) have been unambiguously assigned. Proton NOED spectra were used to show the proximity of both H-3 and H-6 and the hydroxyl groups. Two-dimensional1H–13C NMR correlation spectra of CTA, of its corresponding diacetoxy derivative, and of 3-bromo- and 3,6-dibromo-CTA support the assignments. A regioselective deuterium exchange reaction of the C-3 and C-6 protons of CTA with deuterium oxide was observed during the NMR experiments. This latter finding is strongly indicative of the mode of formation, and of the nature of the chromogen formed in the reaction of CTA with formaldehyde in the well-known CTA-formaldehyde analytical reaction.Keywords: chromotropic acid, 3-bromochromotropic acid, 3,6-dibromochromotropic acid.

ISSN:0008-4042    

DOI:10.1139/v91-180

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The reaction ofN-hydroxy-N-[(1-hydroxycyclohexyl)methyl]benzamide with dimethylether-boron trifluoride gives 5,5-penta-methylene-2-phenyl-4,5-dihydrooxazol-N-oxide(N—O—B)trifluoroborane [3-(2,2,2-trifluoro-1-oxa-2-borataethyl)-5,5- pentamethylence-2-phenyl-1-oxa-3-azonia-2-cyclopentene] in high yield. Crystals of the product are monoclinic,a= 8.1147(4),b= 15.448(1),c= 11.4144(6) Å, β = 95.133(5)°,Z= 4, space groupP21/c. the structure was solved by direct mothods and was refined by full-matrix least-squares procedures toR= 0.043 andRw= 0.058 for 2178 reflections withI≥ 3σ(I). the structure analysis confirms that the title compound has an open-chain boron-nitrogen betaine structure and, as such, is the first isolated and fully characterized open-chain non-chelate boron complex of a cycloimidateN-oxide (cyclohydroximate). Bond lengths (corrected for libration) involving the tetrahedrally coordinated boron atom are O—B = 1.530(3) and F—B = 1.370(2)–1.391(2) Å.Keywords: crystal structure, organoboron compound, boron comp

ISSN:0008-4042    

DOI:10.1139/v91-904

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The reaction ofN,N′-bis(1-cyano-1-methylethyl)-N,N′-dihydroxymethanediamine with phenylboronic acid gives 6,8-bis(1-cyano-1-methylethyl)-2,4-diphenyl-1,3,5-trioxa-6,8-diaza-2,4-diboracyclooctane in good yield. Crystals of the product are monoclinic,a = 9.2681(9),b = 15.946(1),c = 15.491(1) Å, β = 95.946(8)°,Z = 4, space groupP21/n. The structure was solved by direct methods and was refined by full-matrix least-squares procedures toR = 0.047 andRw = 0.064 for 2936 reflections withI ≥ 3σ(I). The central eight-membered O(BON)2C ring has a boat–boat ("saddle") conformation and features cross-ring non-bondingdistances of 2.475 and 2.755 Å, which are significantly shorter than the sum of van der Waals radii (~3.15 Å). Features of the molecular geometry are consistent with weak dative N → B interactions, particularly in the case of the shorter transannular contact. The formally trigonal boron atom involved in the short interaction is displaced 0.098 Å from the plane of its three substituents towards the nitrogen atom while the corresponding displacement for the other boron atom is 0.017 Å. The C(phenyl)—B distances are equal within experimental error at the two B atoms (1.545(3) and 1.547(3) Å), but the (B)O—B and (to a lesser extent) the (N)O—B bonds to the boron atom involved in the shorter transannular interaction are longer than the others (1.371(3) and 1.392(3) vs. 1.354(3) and 1.388(3) Å). The structure may be thought of as an intermediate in the transition from an eight-membered monocylic system to a bridged ring system.Keywords: crystal structure, organoboron compound, boron compound.

ISSN:0008-4042    

DOI:10.1139/v91-181

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The reaction ofN-hydroxypyrrolidine with either oxybis(diphenylborane) or phenylboronic acid gives 1,4-diphenyl-3,3:6,6-bis(tetramethylene)-2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane in moderate yield. Crystals of the product are orthorhombic,a = 10.984(2),b = 14.619(2),c = 12.311(2) Å, Z = 4, space groupPccn. The structure was solved by direct methods and was refined by full-matrix least-squares procedures toR = 0.039 andRw = 0.043 for 908 reflections withI ≥ 3σ(I). This is the first heterocyclic [2.2.1]heptane system containing a six-membered BONBON ring and a B—O—B bridge to be structurally characterized. The molecule has exactC2symmetry with the twofold axis passing through the bridging oxygen atom. Bond lengths involving the tetrahedrally coordinated boron atom are B—O(B) = 1.423(3), B—O(N) = 1.497(3), B—N = 1.703(3), and B—C(phenyl) = 1.577(4) Å.Keywords: 2,5,7-trioxa-3,6-diazonia-1,4-diboratabicyclo[2.2.1]heptane ring system, crystal structure, organoboron compound.

ISSN:0008-4042    

DOI:10.1139/v91-182

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The preparation ofN,N′-bis(1-phenyl-2-nitroethyl)-N,N′-dihydroxymethanediamine and its subsequent reaction with 4-methoxyphenylboronicacid to yield 4,6-bis(1-phenyl-2-nitroethyl)-2-(4-methoxyphenyl)-1,3-dioxa-4,6-diaza-2-boracyclohexane are described. Crystals of the latter compound are monoclinic,a = 8.4790(8),b = 16.2100(9),c = 9.4367(6) Å, β = 109.342(5)°,Z = 2, space groupP21. The structure was solved by direct methods and was refined by full-matrix least-squares procedures toR = 0.032 andRw = 0.039 for 1749 reflections withI ≥ 3σ(I). The molecule has a six-membered BONCNO cycloboronate structure. Bond lengths involving the trigonal planar boron atom are (N)O—B = 1.362(4) and 1.364(5), (aryl)C—B = 1.548(4) Å.Keywords: organoboron compound, crystal structure, cycloboronate, methanediamine.

ISSN:0008-4042    

DOI:10.1139/v91-183

出版商:NRC Research Press    

年代:1991

数据来源: NRC

摘要:

The photoelectrochemistry of a polymer coated electrode exploiting the chromophore bis(maleonitriledithiolato)nickelate(II) to link the redox self-exchange conductor poly(xylylviologen) to the solution couple Fe(CN)63−/4−is described. The diffusion coefficient for the Fe(CN)63−/4−redox couple in the film is 4.2 × 10−9 cm2/s. The system was developed in an attempt to improve on a system where a quaternary ammonium substituted polystyrene/polyvinylpyridine blend films functioned as a good ionic conductor but poor electronic conductor in consequence of the trap states. The expected improvement in electronic conductivity is seen but at the expense of lower ionic mobility.Keywords: polyviologen, bis(maleonitriledithiolato)nickelate(II), polymer conduction, photoelectrode.

ISSN:0008-4042    

DOI:10.1139/v91-184

出版商:NRC Research Press    

年代:1991

数据来源: NRC