Proton Magnetic Resonance Study of Intramolecular Hydrogen Bonding in Halophenols

Rowbotham, J. Brian; Schaefer, Ted

doi:10.1139/v74-444

Cited by 28 publications

(20 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to chloroanisoles, phenols have the hydroxyl group. Orthochlorophenols exhibit both inter-and intramolecular hydro gen bonding, the ortho-chlorine playing an important role [1][2][3][4][5][6][7][8][9]. Chloroanisoles do not exhibit any hydrogen bonding [1][2][3][4][5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Pressure Dependence of the Chlorine NQR in Three Solid Chloro Anisoles

Suresh

Ramesh

Rao

et al. 2001

Zeitschrift Für Naturforschung A

View full text Add to dashboard Cite

The 35C1 Nuclear Quadrupole Resonance (NQR) frequency ( V q ) and spin lattice relaxation time (T{) in the three anisoles 2,3,4-trichloroanisole, 2,3,6-trichloroanisole and 3,5-dichloroanisole have been measured as a function of pressure upto 5.1 kbar at 300 K, and the data have been analysed to estimate the temperature coefficients of the NQR frequency at constant volume. All the three com pounds show a non linear variation of the NQR frequency with pressure, the rate of which is positive and decreases with increasing pressure. In case of 3,5-dichloroanisole the value becomes negative in the higher range of pressure studied. The spin lattice relaxation time T{ in all the three compounds shows a weak dependence on pressure, indicating that the relaxation is mainly due to the torsional motions.

show abstract

Section: Introductionmentioning

confidence: 99%

Pressure Dependence of the Chlorine NQR in Three Solid Chloro Anisoles

Suresh

Ramesh

Rao

et al. 2001

Zeitschrift Für Naturforschung A

View full text Add to dashboard Cite

show abstract

“…Now, if Y = NO, and if the energy of the hydrogen bond is as large as 6 to 7 kcallmol, then 16 is negligibly populated at ambient temperatures; so that 5Jc -0 HZ, in agreement with the observed spectra for 3-fluoro-6-nitrophenol and other nitrophenol derivatives (7). For o-dihalophenol derivatives, on the other hand, 5Jc and 5~t have comparable magnitudes and AGO is a few hundred calories per mole at room temperature (6).…”

Section: Introductionmentioning

confidence: 99%

“…Hz in a variety of phenol derivatives (6,7). Now, if Y = NO, and if the energy of the hydrogen bond is as large as 6 to 7 kcallmol, then 16 is negligibly populated at ambient temperatures; so that 5Jc -0 HZ, in agreement with the observed spectra for 3-fluoro-6-nitrophenol and other nitrophenol derivatives (7).…”

Section: Introductionmentioning

confidence: 99%

Concerning the nonexistence of the intramolecular hydrogen bond in 2-nitrothiophenol

Schaefer¹,

Parr²

1977

Can. J. Chem.

View full text Add to dashboard Cite

. Can. J. Chem. 55,3732 (1977). The long-range spin-spin coupling constants between the sulfhydryl proton and the ring protons in 2-nitrothiophenol in CDCI, and C6D6 solutions suggest the presence of two conformers in which the S-H bond prefers the benzene plane. The conformer in which the S-H bond lies trans to the nitro group is favoured over the cis conformer by a free energy difference of 0.5 ? 0.2 kcal/mol at 305 K. Apparently any intramolecular hydrogen bond is very weak compared to that in 2-nitrophenol.TED SCHAEFER et WILLIAM J. E. PARR. Can. J. Chem. 55,3732 (1977). Les constantes de couplage spin-spin a longue distance entre le proton sulfhydryle et les protons du cycle aromatique du nitro-2 thiophenol dans des solutions CDCI, et C6D6 suggerent la presence de deux conformeres dans lesquels le lien S-H s'oriente dans le plan du cycle. Le conformere dans lequel la liaison S-H se situe trans au groupe nitro est favorise par rapport au conformere cis par une difference d'energie libre de 0.5 i 0.2 kcal/mol a 305 K. I1 apparait qu'une liaison hydrogene intramoleculaire quelconque est vraiment faible comparee a celle observee dans le nitro-2 phenol.

show abstract

“…The assignments for 3 "The signs of these coupling constants are assumed to follow the patterns in Table 1 followed from the characteristic coupling constants for the previously determined (57, 58). 3-methoxy (44) and the hydroxyl protons (45). the stereospecificities "Assigned to the 2-methoxy group, which displays no couplings to other of which imply the conformation displayed in 3.…”

Section: Nuclear Rnagneiic Resonance Samples and Spectramentioning

confidence: 99%

Concerning lone-pair stereospecificity of intramolecular OH hydrogen bonds to oxygen and sulfur in solution

Schaefer¹,

McKinnon²,

Sebastian³

et al. 1987

Can. J. Chem.

View full text Add to dashboard Cite

The 1H nuclear magnetic resonance spectra for CCl4 solutions are analyzed for 2-(thioethyl)phenol, 2,3-dimethoxyphenol, and 8-hydroxythiochroman. The chemical shifts of the hydroxyl protons in these compounds, in 2,3-dihydroxyanisole, and 2-hydroxybenzyl methyl ether are discussed in terms of stereospecific intramolecular OH hydrogen bonds to lone-pair electrons on oxygen and sulfur. The O—H … O hydrogen bonds can be adequately discussed in terms of equivalent lone pairs on oxygen. There is very little difference between the hydrogen bond energies for 2,3-dihydroxyanisole and 2,3-dimethoxyphenol. In the latter the central hydrogen bonded methoxy group lies nearly perpendicular to the ring plane. The O—H … S hydrogen bonds are best described in terms of nonequivalent, 3s and 3p, lone pairs on sulfur. It is estimated that an O—H … H 3s hydrogen bond is at least 8 kJ/mol weaker than an O—H … 3p hydrogen bond. The former is predominant in the thiochroman derivative and the latter in the thioethylphenol, in which the thioethyl group prefers a plane perpendicular to the benzene ring. The long-range benzylic coupling constants in the thiochroman derivative indicate inversion of the saturated ring between distorted half-chair conformations. The boat conformation can be ruled out.

show abstract

Proton Magnetic Resonance Study of Intramolecular Hydrogen Bonding in Halophenols

Cited by 28 publications

References 3 publications

Pressure Dependence of the Chlorine NQR in Three Solid Chloro Anisoles

Pressure Dependence of the Chlorine NQR in Three Solid Chloro Anisoles

Concerning the nonexistence of the intramolecular hydrogen bond in 2-nitrothiophenol

Concerning lone-pair stereospecificity of intramolecular OH hydrogen bonds to oxygen and sulfur in solution

Contact Info

Product

Resources

About