Nuclear magnetic resonance shifts

The side-chain chlorine contents of benzyl chloride, benzal chloride, and benzotrichlorides are determined by hydrolysis with methanolic sodium hydroxide followed by titration with silver nitrate. Total chlorine determination, including ring chlorine, is made by standard combustion methods (55). Several procedures for the gas chromatographic analysis of chlorotoluene mixtures have been described (56,57). Proton and nuclear magnetic resonance shifts, characteristic iafrared absorption bands, and principal mass spectral peaks have been summarized including sources of reference spectra (58). Procedures for measuring trace benzyl chloride ia air (59) and ia water (60) have been described. 

Nuclear Magnetic Resonance Shift Reagents (see Table 19.12)... 

Figure 2. Fluorine Nuclear Magnetic Resonance Shifts, ArCH, F, CCI4. ordinate (both figures) ppm.

R. Sievers,in Nuclear Magnetic Resonance Shift Reagents (R. Sievers, ed.), Academic Press, New York, NY (1973). 

Borowitz, I.J., Yee, K.C., and Crouch, R.K., Determination of stereochemistry in vinyl phosphorylated species by nuclear magnetic resonance shift reagents. Revised mechanistic pathways for the Perkow reaction, /. Org. Chem., 38,1713, 1973. 

Van Meter, F.M. andNenmann, H.M. Solvation of the tris (1,10-phenanthroline) iron (II) cation as measured by solnbility and nuclear magnetic resonance shifts, J. Am. Chem. Soc., 98(6) 1382-1388, 1976. 

For sp carbon atoms, the relationship (6.8) with nuclear magnetic resonance shifts is highly accurate [38]... 

THE INTERPRETATION OF NUCLEAR MAGNETIC RESONANCE SHIFTS IN HYDROGEN BONDING... 

Abstract—Possible causes of the nuclear magnetic resonance shifts in hydrogen bonding are examined in a semi-quantitative manner, The total screening of the proton arises from the secondary magnetic field of the electronic currents induced by the applied external magnetic held. If the bonding system is denoted by X—H 5 e Y then two main possibilities have to be considered. 

C Nuclear Magnetic Resonance Shifts for the Ccrbene Atom in Some Chromium(0)-Carbene Complexes... 

Analysis with chiral nuclear magnetic resonance shift reagents revealed that the isotactic poly (1,4-ketone) products were formed with an average or overall degree of enantioselectivity that was >90%. Using the same catalyst, Jiang and Sen also described the first example of alternating co-polymerization between an internal alkene (2-butene) and carbon monoxide to form an isotactic, optically active poly(l,5-ketone). 

Lanthanide enolates as nuclear magnetic resonance shift reagents... 

The numerous reactions and physical properties that can be correlated with electronic substituent constants suggest that they reflect a basic mechanism for the effect of the substituent on the reaction or the property. Many reactions were correlated by the Hammett equation, such as electrophilic (4, 31, 32, 33), nucleophilic (4, 34) and radical (35, 36, 37). Spectroscopic properties, such as infrared and ultraviolet absorption frequencies and intensities (38). nuclear magnetic resonance shifts of various nuclei, e.g., -H, F, (39), and mass spectroscopic ionization... 

Mao, J.H., Zhang, Y., Oldfield, E. Nuclear magnetic resonance shifts in paramagnetic metallopor-phyrins and metalloproteins. J. Am. Chem. Soc. 2002,124,13911-20. 

Marks, T.J. Porter, R. Kristoff, J.S. Shriver, D.F., in "Nuclear Magnetic Resonance Shift Reagents" Academic Press, New York, 1973, p. 247. 

R. E. Sievers Nuclear Magnetic Resonance Shift Reagents Academic New York, 1973. 

Feibush, B. Richardson, M.F. Sievers, R.E. Springer, C.S., Jr. Complexes of nucleophiles with rare earth chelates. I. Gas chromatographic studies of lanthanide nuclear magnetic resonance shift reagents. Journal of the American Chemical Society 1972, 94 (19), 6717-6724. 

---