Proton chemical shifts of polyhalobenzenes in cyclohexane and carbon tetrachloride. An additivity scheme based on pairwise parameters

Richardson, Benny R.; Schaefer, Ted

doi:10.1139/v68-358

Cited by 20 publications

(6 citation statements)

References 10 publications

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“…This implies that the water released from the resin at higher temperature originates from the bulk water in the resin and not from the cation hydration sphere. The molar shift, 0.215 ppm, is somewhat larger than has been reported for styrene based cation resin (3,4) and for that recently reported for Mg2+ ion in water, 0.153 ppm (5).…”

Section: Resultscontrasting

confidence: 55%

Nuclear magnetic resonance method for determining the moisture holding capacity of cation exchange resins as a function of temperature

Frankel¹

1973

Anal. Chem.

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Section: Resultscontrasting

confidence: 55%

Nuclear magnetic resonance method for determining the moisture holding capacity of cation exchange resins as a function of temperature

Frankel¹

1973

Anal. Chem.

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“…deshield the methine proton more in 2 than in 1 (12). The free energy difference between 1 and 2 is 50 f 20 cal/mol at 240 OK.…”

Section: ( 2 ) Assignment Of Peaks At High Temperaturementioning

confidence: 94%

Proton Magnetic Resonance Studies of Rotational Isomerism in Halotoluene Derivatives. VI. Rotational Barrier and Conformational Energy Differences in α,α,2,3,6-Pentachlorotoluene

Stewart¹,

Schaefer²,

Hutton³

et al. 1971

Can. J. Chem.

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Rotation by n. radians about the spZ-sp3 carbonxarbon bond of the dichloromethyl group in u,u,2,3,6-pentachlorotoluene interconverts the two conformations which are characterized by coplanarity of the aromatic ring with the C-H bond of the sidechain. The ring protons undergo effective nonmutual exchange during this rotation. The rate of rotation as a function of temperature is extracted by lineshape fitting of the ring p.m.r. spectra. The rotation is characterized by a negative entropy of activation. The free energy difference between the two conformations is 50 f 20 cal/mol at 240 OK.Une rotation de n. radians autour de la liaison carbonexarbone sp2-sp3 du groupe dichlorom6thyle du pentachloro-u,u,2,3,6 toluene interconvertit les deux conformations qui sont caract6risCs par une disposition coplanaire du noyau aromatique et de la liaison C-H du substituant. Les protons du noyau changent leur environnement magnktique durant cette rotation et on peut obtenir la vitesse de rotation en fonction de la temperature par une simulation de la forme de ra,ie du spectre de rksonance magnktique. Cette rotation est caracterisie par une entropie d'activation nkgative. La diffkrence d'6nergie libre entre les deux conformations est 50 f 20 cal/mol A 240 OK.

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“…All peaks were assigned to calculated transitions, chemical shifts were assigned on the basis of known halogen atom substituent effects (26,27), and the signs of the five-bond couplings were determined by double irradiations (28).…”

Section: Analysis Of Spectramentioning

confidence: 99%

Proton Magnetic Resonance Study of Intramolecular Hydrogen Bonding in Halophenols

Rowbotham¹,

Schaefer²

1974

Can. J. Chem.

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The long-range spin-spin coupling constants over five bonds between the hydroxyl proton and the ring protons in a series of trihalophenols imply that the intramolecular hydrogen bond strength (negative entlialpy) to fluorine is greater than that to iodine by 75 + 20 cal,mol, whereas the strengths to chlorine and bromine are 460 i 60 caliniol greater than to iodine. If a distinction can be made between chlorine and bromine, then chlorine-hydrogen bonds more strongly by only a few tens of calories per mol. The meas~lrenients were ~u a d e mainly o n dilute solutions in carbon tetrachloride a t 32 ' C . Chern. 52.3037 (1974) Les valeurs des constantes de couplage spin-spin a longue distance sur cinq liens entre le proton de I'hydroxyle et les protons du cycle ont ete mesurees pour une serie de phenols trihalogenes: ces valeurs impliq~le~it que la force du lien hydrogene intramoleculaire (entlialpie negative) vers le fluor est plus grande que celle Lers I'iode par 75 I 20 cal mol alors qne les forces des liens hydrogenes intraniolCculaires vers le chlore et le bronie sont plus grandes que celle de I'iode par 460 i 60 cal/niol. Si l'on peut faire une distinction entre le chlore et le brome on note alors que les atomes de chlore font des liens q~t i sont plus forts: la difference n'est que quelques dizaines de calories par niol. O n a fait les niesures principalenlent sur des solutions diluees dans le tetrachlornre de carbone a 32 C .[Traduit par le journal]

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Proton chemical shifts of polyhalobenzenes in cyclohexane and carbon tetrachloride. An additivity scheme based on pairwise parameters

Cited by 20 publications

References 10 publications

Nuclear magnetic resonance method for determining the moisture holding capacity of cation exchange resins as a function of temperature

Nuclear magnetic resonance method for determining the moisture holding capacity of cation exchange resins as a function of temperature

Proton Magnetic Resonance Studies of Rotational Isomerism in Halotoluene Derivatives. VI. Rotational Barrier and Conformational Energy Differences in α,α,2,3,6-Pentachlorotoluene

Proton Magnetic Resonance Study of Intramolecular Hydrogen Bonding in Halophenols

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