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Dispiro[2.0.2.2]oct-7-ene 1 was synthesized by debrominatioa of cis- and trans-7,8-dibromodispiro[2.0.2.2]octane 3a with LAH and by dechlorination of cis- and trans-7,8-dichlorodispiro[2.0.2.2]octane 3b with magnesium. Stepwise electrophilic additions to 1 of HBr, HI, Br2 and Cl2 were studied. The major products (and yields) from these reactions were: 7-bromodispiro[2.0.2.2]octane 2a (43%), 4-iodo-4,5-ethanospiro[2,3]hexane 4b (ca. 50%); trans-3a (40%); and cis-3b (20%). Free-radical addition of hydrogen bromide to 1 gave an 80% yield of 7-bromodispiro[2.0.2.2]octane 2a. At ?10°, hydroboration-oxidation of 1 was found to give mainly 7-hydroxydispiro[2.0.2.2]octane 2a in ca. 90% yield; at 25°, near equal amounts of 2c and 4-(2-hydroxyethyl) spiro[2.3]hex-4-ene 14 were obtained. 相似文献
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A. F. Woitkewitsch F. Werr E. Bottini L. W. Raymond W. Jerschow H. Jesser und E. Thomae 《Fresenius' Journal of Analytical Chemistry》1938,114(1-2):72-74
Ohne Zusammenfassung 相似文献
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Overtone spectrum of o, m and p-nitrobenzaldehydes and p-chlorobenzaldehyde has been studied in 2000–12000 cm−1 region. Vibrational frequencies and anharmonicity constants for aryl as well as alkyl CH stretch vibrations have been determined.
We have also determined the internuclear distances for the aryl CH bond in the different molecules. The small variation observed
in these distances is an indication of the substitution effect.
It is observed that in the case of p-disubstituted benzens, the shift in aryl CH bond is proportional to sum of the Hammet σ of the substituents. However in the
case of o-disubstituted benzenes it is only 80% of the para-substituted shift. 相似文献
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The steric requirements for the synchronous fragmentation of γ-aminohalides as previously postulated have been confirmed by a study of the solvolysis of stereoisomeric 3β- and 3β-chloro-tropanes and -nortropanes. 3β-chloro-tropanes ( 7 a ) and 3β-chloro-nortropane ( 7 b ), which fulfil the stereoelectronic requirements, undergo quantitative fragmentation in 80 vol.% ethanol. They react 1.35 × 104 and 1.35 × 103 times, respectively, as fast as the ‘homomorphous’ exo-3-chloro-bicyclo[3.2.1]octane ( 12 a ). Fragmentation therefore takes place by the synchronous mechanism. 相似文献
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Bicyclo[3.2.1]octa-2,3-diene (2) and 1,2-cycloheptadiene (3), generated by treatment of the corresponding dichlorides 4 and 5 with magnesium, were found to undergo cycloaddition reactions with 2,3-dimethylbutadiene, styrene, and 1,3-cyclopentadiene. 2, but not 3, was also found to undergo a (2 + 2) cycloaddition reaction with cis-pentadiene. The relative reactivities of 2 and 3 with cis-pentadiene, 2,3-dimethylbutadiene, styrene, and 1,3-cyclopentadiene at 60° in THF were found to be: 0·18, —; 1·0, 1·0; 0·60, 7·5; and 4·0, 150. 相似文献
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Rita Baraldi Gianpaolo Bertazza Judit Bogino Virginia Luna Ruben Bottini 《Photochemistry and photobiology》1995,62(4):800-803
Abstract— The endogenous levels of indole-3-acetic acid (IAA), abscisic acid (ABA) and gibberellins (GA) were examined by gas chromatography-mass spectrometry in Prunus cerasus plantlets grown under different light conditions in relation to previous work on the photocontrol of stem elongation. The endogenous levels of free and conjugated IAA in the apical sections of red-grown shoots were about two-fold higher than those in the blue-treated plants, and these corresponded with maximum shoot elongation. By contrast, greater concentrations of ABA and GA were found in blue-grown plants compared to red with intermediate shoot growth. When blue was combined with red or far red, lower levels of IAA, ABA and GA correlated with less growth. These results suggest that the regulation of stem elongation by phytochrome and a blue-absorbing pigment may, at least in part, occur through a modulation of hormone levels. 相似文献
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The growing interest on first- and second-generation biofuels requires the development of thermodynamic tools with predictive capacity for mixtures containing a wide variety of organo-oxygenated compounds, water and hydrocarbons. Modeling this type of mixtures is challenging due to the presence of association and solvation effects. In this work, we present a revision of the group contribution with association equation of state (GCA-EoS) parameters, with the purpose of extending and improving the predictive capacity of the model for systems containing water, alcohols and hydrocarbons. 相似文献