Zur Endokrinologie der Pubert�t und Pr�pubert�t

Schwenk, A.

doi:10.1007/bf00442381

Cited by 6 publications

(1 citation statement)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…I n Fig. 2 the A value of mesitylene is also given and suggests that electron donors do indeed cause negative A values.ll "This conclusion is confirmed by our benzene solvent effect studies (14). Negative A values for benzene a s solvent have been observed previously in the presence of strong electron donors (16).…”

Section: Charge Efsectsupporting

confidence: 79%

Carbon tetrachloride as solvent in proton magnetic resonance. Importance of size and charge effects of proximate substituents

Schaefer¹,

Richardson²,

Schwenk³

1968

Can. J. Chem.

View full text Add to dashboard Cite

A model (not a theory), based on steric and charge removal characteristics of the substituents, is used to rationalize the low-field shifts caused by carbon tetrachloride (compared to cyclohexane) in the proton resonance spectra of 22 polyhalosubstituted benzenes. The low-field shifts are as large as 0.16 p.p.m. and these are found for protons situated between two ortho fluorine substituents. Larger halogens present a steric hindrance to the approach of the polarizable C-C1 bonds of the solvent and lead to smaller shifts. The charge removed from the region of the C-H bonds by the substituents is estimated by means of a function of the bond dipole divided by the bond length. A shape effect, arising when two hydrogens are ortho to each other, also appears to be present if there are bulky distant groups.

show abstract

Section: Charge Efsectsupporting

confidence: 79%