An experimental and ab inttio molecular orbital study of benzaldehyde and isomeric phthalaldehydes

Lumbroso, H.; Liégeois, G.; Pappalardo, Giuseppe; Librando, Vito

doi:10.1016/0022-2860(80)85236-7

Cited by 13 publications

(11 citation statements)

References 42 publications

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“…Alternatively, if only the planar tt and ct forms existed in dioxane, then the ct form was 60% abundant at this temperature (6). The same assumption, applied to the dipole moment in benzene solution, led to 64% as the abundance of the ct conformer (7). In the latter study, the dipole moment did not change significantly between 287 and 327 K.…”

Section: Introductionmentioning

confidence: 50%

“…The 1,4 isomer has degenerate chemical shifts for the ring protons and is not amenable to this approach. In any event, the 13C nmr and dipole moment studies agree that it exists in equal proportions of the ct and cc conformers (6)(7)(8)14). Accordingly, the 'H nmr spectra were analyzed for CCl,, C6D6, and (CD3)2C=0 solutions of the 1,2 and 1,3 isomers.…”

Section: Introductionmentioning

confidence: 99%

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Long-range proton coupling constants and molecular orbital calculations as indicators of conformational populations of benzene-1,2- and -1,3-dicarbaldehydes

Schaefer¹,

Penner²,

Sebastian³

et al. 1986

Can. J. Chem.

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. Can. J. Chem. 64, 158 (1986).The 'H nrnr spectra of the benzene-1,2-and -1,3-dicarbaldehydes in carbon tetrachloride, benzene-d6, and acetone-d6 solutions at 300 K are analyzed. The stereospecific long-range couplings over five formal bonds between the sidechain and ring protons show that the 1,2 isomer exists as an 87: 13 mixture of the cis-trans and trans-trans conformers in carbon tetrachloride. These populations are insensitive to solvent. Molecular orbital calculations utilizing extensive geometry optimization procedures imply that the cis-cis form, with proximate C=O bonds, is indeed of negligible significance as assumed in obtaining the populations of the other forms. Further calculations define a pathway of relatively low energy for interconversion of the two abundant forms, in agreement with dynamic nrnr studies. For the 1,3 isomer the long-range couplings provide a check of the conformer populations deduced from dipole moment and "C nmr studies. For example, if the cis-trans form is 70% abundant, as deduced from the dipole moment in benzene solution, then the long-range couplings imply that the population of the cis-cis conformer is insignificant. TED SCHAEFER, GLENN H. PENNER, RUDY SEBASTIAN et CRAIG S. TAKEUCHI. Can. J. Chem. 64, 158 (1986). On analyse les spectres rmn du 'H des benzkne dicarbaldehydes-1,2 et -1,3 qui ont t t t mesurCs a 300 K et dans des solutions dans le tttrachlorure de carbone, le benzkne-d6 et 1'acCtone-d6. Le couplage stCrCospCcifique a longue distance a travers cinq liaisons normales entre les protons du cycle et ceux de la chaine latCrale indique que dans le tktrachlorure de carbone l'isomkre 1,2 existe sous la forme d'un mtlange 87: 13 des conformkres cis-trans et trans-trans. Le solvant n'a aucune influence sur cette rtpartition. Les calculs d'orbitales molCculaires, faisant appel a des procCdCs extensifs d'optimisation gComCtrique, suggkrent que la forme cis-cis ayant des liaisons s'approchant de C=O n'a pratiquement aucune importance dans la dktermination des populations des autres formes. Des calculs plus pousses dkfinissent un chemin rkactionnel de faible Cnergie pour l'interconversion des deux formes abondantes et ceci est en accord avec les Ctudes de la rmn dynamique. Dans le cas de l'isomkre-1,3, les couplages B longue distance constituent une ~Crification des populations des conformkres qui ont CtC dCduites a partir des Ctudes du moment dipolaire et de la rmn du I3C. Par exemple, si la forme cis-trans est a 70%, tel que dCduit t i partir du moment dipolaire en solution dans le benzkne, alors le couplage a longue distance implique que la population de la forme cis-cis n'est pas significative.[Traduit par le journal]

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Section: Introductionmentioning

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Long-range proton coupling constants and molecular orbital calculations as indicators of conformational populations of benzene-1,2- and -1,3-dicarbaldehydes

Schaefer¹,

Penner²,

Sebastian³

et al. 1986

Can. J. Chem.

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“…Therefore it is comprehensible that the barrier to internal rotation of the CHO group in I is by 4.8 kJ/mol smaller than in benzaldehyde [3]. The energy difference, E (It Ic), of both isomers yielded by ab initio (6-31G) calculations are 0.88 and 0.46 kJ/mol [13,14]. A small preference of the It isomer can be deduced from the intramolecular dipolar interaction whose energy is ca.…”

Section: Methodsmentioning

confidence: 97%

“…The activation parameters for the rotational process have been determined using NMR and far-infrared methods [1][2][3][4][5][6] as well as quantum-chemical calculations [9][10][11][12][13][14][15]. A relatively high barrier of activation is due to the partial double character of the carbon-carbon bond caused by delocalization of π -electrons.…”

Section: Introductionmentioning

confidence: 99%

Solvent influence on the rotational isomerism in terephthalaldehyde

et al. 2006

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Experimental and theoretical studies were carried out in order to investigate the rotational isomerism of terephthalaldehyde. The dipole moment measurements and infrared spectroscopy in Ar matrix and using various solvents were performed experimentally. In order to supplement the experimental study, both static and dynamical theoretical calculations were performed. IR spectra and potential energy distribution (PED) were calculated for both cis and trans isomers of terephthalaldehyde in gas phase using B3LYP/6-31G(d,p) level of theory. Further calculations consisted of conformational analysis were performed in order to estimate the rotational barrier and relative stabilities of isomers. The DFT theory with B3LYP functional and four double-zeta and triple-zeta basis sets served as framework for this part of calculations. Semiempirical AM1 and PM3 methods were also used for gas-phase modeling. Molecular dynamics using MM3 force field was applied to study the preferences of solvent molecules' orientation around the studied molecule. Additionally, the effect of solvent polarity on the Gibbs energy of the trans cis equilibrium was analyzed in terms of the continuum dielectric medium models.

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“…10 This article describes an acid-catalyzed degradation mech-A positive-tone self-developing photoresist was formulated early with end-capped poly(phthalaldeanism of end-capped poly(phthalaldehyde) in detail by quantum chemical calculations, although the hyde) and a photochemical acid-generator such as triphenylsulfonium hexafluoroarsenate, diphenylpreliminary mechanism has been already published. 11 iodonium hexafluoroarsenate, etc.…”

Section: Introductionmentioning

confidence: 99%

Acid‐catalyzed degradation mechanism of poly(phthalaldehyde): Unzipping reaction of chemical amplification resist

Tsuda

Hata

Nishida

et al. 1997

J. Polym. Sci. A Polym. Chem.

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An experimental and ab inttio molecular orbital study of benzaldehyde and isomeric phthalaldehydes

Cited by 13 publications

References 42 publications

Long-range proton coupling constants and molecular orbital calculations as indicators of conformational populations of benzene-1,2- and -1,3-dicarbaldehydes

Long-range proton coupling constants and molecular orbital calculations as indicators of conformational populations of benzene-1,2- and -1,3-dicarbaldehydes

Solvent influence on the rotational isomerism in terephthalaldehyde

Acid‐catalyzed degradation mechanism of poly(phthalaldehyde): Unzipping reaction of chemical amplification resist

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