Carbon Couplings

Polymerization by G—G Goupling. An aromatic carbon—carbon coupling reaction has been employed for the synthesis of rigid rod-like polyimides from imide-containing dibromo compounds and aromatic diboronic acids ia the presence of palladium catalyst, Pd[P(CgH )2]4 (79,80). 

Table II summarizes analytical data for dissolved inorganic matter in a number of natural water sources (J3, 9, J 9, 20, 21). Because of the interaction of rainwater with soil and surface minerals, waters in lakes, rivers and shallow wells (<50m) are quite different and vary considerably from one location to another. Nevertheless, the table gives a useful picture of how the composition of natural water changes in the sequence rain ->- surface water deep bedrock water in a granitic environment. Changes with depth may be considerable as illustrated by the Stripa mine studies (22) and other recent surveys (23). Typical changes are an increase in pH and decrease in total carbonate (coupled), a decrease in 02 and Eh (coupled), and an increase in dissolved inorganic constituents. The total salt concentration can vary by a factor of 10-100 with depth in the same borehole as a consequence of the presence of strata with relict sea water. Pockets with such water seem to be common in Scandinavian granite at >100 m depth.

Bardaji, M., Gimeno, M.C., Jones, P.G., Laguna, A., Laguna, M., Merchan, F. and Romeo, I. (1997) Carbon-Carbon Coupling via Nucleophilic Addition of a Gold(l) Methanide Complex to Heterocumulenes. Organometallics, 16(5), 1083-1085. 

Carbon-carbon and non-carbon-carbon coupling reactions... 

Stahl, M., Schopfer, U., Frenking, G., Hoffmann, R. W., 1997, Conformational Analysis with Carbon-Carbon Coupling Constants. A Density Functional and Molecular Mechanics Study , J. Org. Chem., 62, 3702. 

A zinc-mediated carbon-carbon coupling reaction can be carried out on the metallated form of (t-butyldimethylsilyl)(2-pyridylmethyl)amine, formed in reaction with dimethylzinc. The isolated dimeric species can be reacted with further dimethyl zinc to give bis(methylzinc)-l,2-dipyridyl-l,2-bis(t-butyldimethylsilylamido)ethane, which contains two N3C coordinated zinc centers.89... 

The two axes (dimensions) in our 2D spectra are thus both frequency axes. We shall see as we continue that we can adjust our experiment so as to choose different types of frequency information. An early experiment, known as the J-resolved experiment, was designed in such a way that one axis was the (proton or carbon) chemical shift axis and the other the one-bond proton-carbon coupling constant. Flowever, this experiment is not generally very useful for structural determination, so that we shall not discuss it here. 

Thus tin chemical shifts are of considerable use in structural studies. In addition, tin-element coupling constants are easily visible, and particularly in proton and carbon-13 spectra the relevant coupling constant values are of diagnostic use for example both tin-proton and tin-carbon coupling constants show a Karplus-type behaviour. 

Lead-proton and lead-carbon coupling constant values have structural uses, as with tin. Lead chemical shifts are quite sensitive to temperature variations. 

Scheme 1.3 Pd(0) NP-catalyzed carbon-carbon coupling reactions in ILs A[36,94, 102, 103,113,...

Astruc, D. (2007) Palladium nanoparticles as efficient green homogeneous and heterogeneous carbon-carbon coupling precatalysts a unifying view. Inorganic Chemistry, 46 (6), 1884-1894. 

V. Wray, Carbon-carbon coupling constants a compilation of data and a practical guide. In Progress in Nuclear Magnetic Resonance Spectroscopy 1979, Vol. 13, 1979, pp. 177-256. 

T. Parella, 2D methods for the measurement of long-range proton-carbon coupling constants, in Multidimensional NMR Methods for the Solution State, G. A. Morris and J. W. Emsley (eds.), John Wiley Sons Ltd, Chichester, 2010, pp. 305-314. 

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