Cramer studies

Cramer studied the mechanism using Rh compounds [123, 124], The linear dimerization of acrylonitrile in the presence of hydrogen and a ruthenium catalyst to form 1,4-dicyano-l-butene [125-127] received much interest in industrial laboratories, mostly in Japan, so a large number of patents have been filed, in some of which palladium catalysts have also been claimed. The above compound can be hydrogenated to give the industrially important adipodinitrile and hexa-methylene diamine. 

A more significant body of literature focuses on the use of protoplasts in understanding processes related to stress tolerance. The role of Ca in salt toleranee has been evaluated using maize root protoplasts. Exposure of the plasmalemma directly to external media revealed a non-specific replacement of Ca by salt. Sodium was found to replace Ca though this could be reversed by adding more Ca (Lynch, Cramer Lauchli, 1987). This approach assists in understanding the role of specific ion interaction in enhancing salt tolerance and is potentially applicable to studies on the molecular basis for ion specificity of plant membranes. 

Inhibition of ALAD and stimulation of ALAS result in increased levels of ALA in blood or plasma and in urine. For example, in a case report of a 53-year-old man with an 11-year exposure to lead from removing old lead-based paint from a bridge, a PbB level of 55 pg/dL was associated with elevated urinary ALA (Pollock and Ibels 1986). The results of the Meredith et al. (1978) study on lead workers and controls indicated an exponential relationship between PbB and blood ALA. Numerous studies reported direct correlations between PbB level and log urinary ALA in workers. Some of these studies indicated that correlations can be seen at PbB levels of <40 pg/dL (Lauwerys et al. 1974 Selander and Cramer 1970 Solliway et al. 1996), although the slope may be different (less steep) than at PbB levels of >40 pg/dL. In a study of 98 occupationally exposed subjects (51 pg/dL, mean PbB) and 85 matched controls (20.9 pg/dL. mean PbB) it was found that log ZPP and log ALA in urine correlated well with PbB levels (Gennart et al. 1992a). In the exposed group, the mean ZPP was 4 times higher than in the controls, whereas urinary ALA was increased 2-fold. 

Cramer and co-workers (1967) have recently measured rate constants as well as equilibrium constants for the association of p-nitrophenol and a series of azo dyes with cydohexaamylose. The general structure of the dyes employed in this study is illustrated in Fig. 4. p-Nitrophenol and p-nitro-phenolate bind to cydohexaamylose with rate constants of about 108 M l sec-1, near the diffusion-controlled limit. Within the series of dyes, however, binding rates decrease by more than seven orders of magnitude as the steric bulk of the dye is increased. Equilibrium constants, on the other hand, are roughly independent of the steric nature of the substrate, indicating that association and dissociation rates are affected by similar... 

This preferential formation of 1 1 adduct to form 1,4-hexadiene in a mixture of ethylene and butadiene was further studied by Cramer (4). He concluded that the results appeared to be the consequence of thermodynamic control reactions through a relatively stable 7r-crotyl Rh complex. 

The rate also varies with butadiene concentration. However, the order of the rate dependence on butadiene concentration is temperature-de-pendent, i.e., a fractional order (0.34) at 30°C and first-order at 50°C (Tables II and III). Cramer s (4, 7) explanation for this temperature effect on the kinetics is that, at 50°C, the insertion reaction to form 4 from 3, although still slow, is no longer rate-determining. Rather, the rate-determining step is the conversion of the hexyl species in 4 into 1,4-hexadiene or the release of hexadiene from the catalyst complex. This interaction involves a hydride transfer from the hexyl ligand to a coordinated butadiene. This transfer should be fast, as indicated by some earlier studies of Rh-catalyzed olefin isomerization reactions (8). The slow release of the hexadiene is therefore attributed to the low concentration of butadiene. Thus, Scheme 2 can be expanded to include complex 6, as shown in Scheme 3. The rate of release of hexadiene depends on the concentra-... 

In chapter 1, Profs. Cramer and Truhlar provide an overview of the current status of continuum models of solvation. They examine available continuum models and computational techniques implementing such models for both electrostatic and non-electrostatic components of the free energy of solvation. They then consider a number of case studies with particular focus on the prediction of heterocyclic tautomeric equilibria. In the discussion of the latter they focus attention on the subtleties of actual chemical systems and some of the danger in applying continuum models uncritically. They hope the reader will emerge with a balanced appreciation of the power and limitations of these methods. In the last section they offer a brief overview of methods to extend continuum solvation modeling to account for dynamic effects in spectroscopy and kinetics. Their conclusion is that there has been tremendous progress in the development and practical implementation of useful continuum models in the last five years. These techniques are now poised to allow quantum chemistry to have the same revolutionary impact on condensed-phase chemistry as the last 25 years have witnessed for gas-phase chemistry. 

There have been numerous applications of continuum models to equilibria and reactions in solution surveys of these and extensive listings are provided by Cramer and Truhlar.16 Other studies have focused upon the effects of solvents upon solute molecular properties, such as electronic and vibrational spectra,16 dipole moments, nuclear quadrupole and spin-spin coupling constants and circular dichroism.12... 

Nucleophilic addition of phenolic nucleophiles to l,l-dicyano-2-arylethenes in the gas phase and in water has been studied theoretically" using the semiempirical AMI method and the Cramer-Truhlar solvation model SM2.1. The difference between the Brpnsted coefficients (a" = 0.81 and P" =0.65) determined for the gas-phase reaction is indicative of a small positive transition state imbalance of / = 0.16. For reaction in water the estimates (a" = 0.61 and P" = 0.36, giving I = 0.25) are close to the experimental values (a" = 0.55 and P" = 0.35) obtained with amine bases, and the small imbalance is as expected for a reaction involving no hybridization change at the incipient carbanion site. 

Freudenberg later concurred with French s results, after studying the X-ray measurements of Borchert and also his and Cramer s optical rotation data. He also proposed that the gamma dextrin consisted of eight d-glucosyl residues joined by a linkages in a cyclic structure, as in the case of the alpha and beta dextrins. 

Kringlen E, Torgerson S, Cramer V (2001) A Norwegian psychiatric epidemiological study. Am J Psychiatry 158 1091-1098... 

Harlow, and D. W. Cramer. Population based study of coffee, alcohol and tobacco use and risk of ovarian cancer. Int J Cane 2000 88(2) 313-318. 

Rosenheck, R, Cramer, J., Xu, W., et al.. A comparison of clozapine and haloperidol in hospitalized patients with refractory schizophrenia Department of Veterans Affairs Co-operative Study Group on clozapine in refractory schizophrenia. N. Engl. J. Med. 337, 809-815. 1997. 

C. J. Cramer, J. Chem. Soc. Perkin 2 1998, 1007. This paper contains an appreciation of the important contrihutions of Paul Dowd to the study of trimethylenemethane and tetraamethylenee thane. 

Cramer, J. J. Smellie, J. 1994. Final Report of the AECL/SKB Cigar Lake Analog Study. Technical Report AECL-10851, COG-93-147, SKB TR 94-04, 393 p. 

Sunder, S., Taylor, P. Cramer, J. J. 1988. XPS and XRD studies of uranium rich minerals from Cigar Lake, Saskatchewan. Materials Research Society Symposia Proceedings, 112, 465-472. 

Sunder, S., Cramer, J. J. Miller, N. H. 1996. Geochemistry of the Cigar Lake deposit XPS studies. Radiochimica Acta, 74, 303-307. 

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