The Ultraviolet Absorption Spectra of Simple Unsaturated Compounds. I. Mono- and p-Disubstituted Benzene Derivatives

Doub, Leonard; Vandenbelt, J. M.

doi:10.1021/ja01203a046

Cited by 336 publications

(99 citation statements)

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“…These results are to be expected for the 3-protonated structures, since it has been observed that replacement of a inethyl by an -NH3+ group has only a ininor effect on the ultraviolet spectra of many aroinatic compounds (38,39,40). I t is evident that the absorption characteristics of protonated benzamide are equally compatible with an N-or an 0-protonated structure, and are not exclusivel>-i l l favor of the latter, as Han tzsch (4) …”

Section: Ultraviolet Spectra Of Protonated Benzamidessupporting

confidence: 62%

Protonation of the Amide Group: I. The Basicities of Substituted Benzamides

Edward¹,

Chang²,

Yates³

et al. 1960

Can. J. Chem.

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The basicities of benzamide and of 11 meta-and para-substituted benzamicles in sulphuric acid media have been determined by a spectrophotometric method. The pKnn+ values of the protonated benzamides were found to be proportional to the Hammett CT constants for the substituents, unlike the pRsn+ values of the protonated benzaldehydes, acetophenones, and benzoic acids, which are approxi~llately proportional to u+ constants. The lack of conjugation between the protonated amide group and the ring, which is indicated by these results, is most easily interpreted in terms of N-protonation although 0-protonation cannot be completely excluded. Irarious other aspects of the problem of N-versus 0-protonation are also discussed.

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Section: Ultraviolet Spectra Of Protonated Benzamidessupporting

confidence: 62%

Protonation of the Amide Group: I. The Basicities of Substituted Benzamides

Edward¹,

Chang²,

Yates³

et al. 1960

Can. J. Chem.

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“…The most prominent band found in the absorption spectra with maximum at 285 nm, ∊ ≈ 9000-10 000 M −1 cm −1 , is due to a π−π* transition (band 1 La or K) of the p-nitrobenzyl chromophore. 34 It is noteworthy that the corresponding CD band is negative with comparable amplitude for both compounds Yb1 and Yb2 (ESI, Figure S2). Given the high sensitivity of CD spectroscopy to the absolute conformation, in particular for benzenoid transitions 1 L a and 1 L b , 35 CD spectra demonstrate that the chirality sensed by the two aromatic rings is similar for the two compounds and is only determined by the absolute configuration at the chiral carbon on the cycle.…”

Section: Uv-cd Spectroscopymentioning

confidence: 92%

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

et al. 2005

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Studies of the structural, physical, and chemical properties of the lanthanide(III) complexes of DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and related ligands are often complicated by the presence of two coordination isomers in solution. Since these coordination isomers are in exchange and cannot be separated, many techniques offer information only on the weighted average of the two isomers. Lanthanide ion complexes formed with the ligands S(RRRR)NO 2 BnDOTMA and S(SSSS)NO 2 BnDOTMA preferentially adopt only one of the two common coordination isomers in solution, so the ytterbium complexes of these ligands offer a unique opportunity to study the nearinfrared circular dichroism (NIR-CD) characteristics of each coordination geometry in isolation. The spectra acquired support many of the conclusions and assumptions of previous studies and demonstrate that this spectroscopy is particularly sensitive to the distortion of the coordination polyhedron. This will have particularly relevant consequences when studying achiral YbDOTA-like systems forming labile adducts with (chiral) hosts and receptors.

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“…The ultraviolet absorption spectra of substituted benzenes (1,2) and of vinyl ketones (3) have been investigated in detail.…”

Section: Introductionmentioning

confidence: 99%

Functional-group and substituent effects, both steric and electronic, upon the ultraviolet absorption spectra of some conjugated heteroenoid compounds

Currie¹,

Lough²,

Silver³

et al. 1967

Can. J. Chem.

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The positions of the long-wavelength maxima in the spectra of some 300 compounds of generalized formula I may be accommodated by assuming that the observed maximum is equal to that of styrene + AX (the conjugative effect of A) + Ah' (the inductive effect of B) + ZAX" (the sum of the steric effects of the A, B, and phenyl groups) + D (an empirical parameter related to S and Y). These arguments have been extended to the spectra of 11. AX' is related t o the u value for meta-substituted benzene derivatives or to u*. D for meta-and para-substituted derivatives roughly correlates with the appropriate uf values, whereas D for ortho-substituted derivatives is related t o a simple function involving the D value for para substitution and the steric substituent constant, E,. For compounds of generalized formula 111, the electronic effects of the A and B groups cancel but the steric effects are additive.Multiple bands occur in the long-wavelength region of the spectra for compounds containing halogen, alkoxy, or amino groups. These groups are highly polarizable and are considered to function both as electron donors and electron sinks.

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The Ultraviolet Absorption Spectra of Simple Unsaturated Compounds. I. Mono- and p-Disubstituted Benzene Derivatives

Cited by 336 publications

References 0 publications

Protonation of the Amide Group: I. The Basicities of Substituted Benzamides

Protonation of the Amide Group: I. The Basicities of Substituted Benzamides

Structural and Chiroptical Properties of the Two Coordination Isomers of YbDOTA-Type Complexes

Functional-group and substituent effects, both steric and electronic, upon the ultraviolet absorption spectra of some conjugated heteroenoid compounds

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