Organic reactions, in solution

I hope therefore that, in the not too distant future, an expert on the modeling of organic reactions in solution will investigate the dediazoniation of aromatic or aliphatic diazonium ions in water. 

The importance of solvation on reaction surfaces is evident in striking medium dependence of reaction rates, particularly for polar reactions, and in variations of product distributions as for methyl formate discussed above and of relative reactivities (18,26). Thus, in order to obtain a molecular level understanding of the influence of solvation on the energetics and courses of reactions, we have carried out statistical mechanics simulations that have yielded free energy of activation profiles (30) for several organic reactions in solution (11.18.19.31. ... 

The rate of a chemical reaction depends on temperature. A rule of thumb for many organic reactions in solution is that a 10 °C change in temperature causes a two- to three-fold change in rate of reaction [25]. To study the temperature dependence of solid-phase reactions, the cleavage reaction of resin (35) with n-butyla-mine at 20, 40 and 60 °C were carried out. The cleavage time courses and pseudo-first-order rate fits at these three temperatures are shown in Fig. 12.20. The rate constants from single bead FTIR analysis are Hsted in Tab. 12.4. Compared with the reaction at 20 °C, the solid-phase cleavage reaction of resin 3b was two times faster at 40 °C and four times faster at 60 °C. 

Metal Ion Catalysis of Nucleophilic Organic Reactions in Solution... 

Maetal ions are known to catalyze many organic reactions in solution. Some ex-m amples of metal ion catalysis are discussed here and an attempt is made to point out the underlying principles concerning metal ion catalysis of organic reactions. Since the field is very large, it is necessary to limit discussion and to omit the topics of metal ion-catalyzed redox reactions and metal ion-catalyzed polymerization reactions, although the latter are extremely important. 

Solid-phase organic syntheses typically use large excesses of reagents to drive reactions to completion so that, ideally, products liberated from resins should not require purification. Optimization of conditions is a critical part of solid-phase syntheses. Transfer of organic reactions in solution to a solid matrix is not a trivial undertaking, and lack of analytical methods accentuates this problem. Libraries prepared without adequate refinement of conditions tend to be of poor quality. For libraries so large that all the constituents cannot be fully characterized, well-optimized reaction conditions are absolutely essential. Techniques like split and pool, 2 for instance, can only be applied successfully after thorough optimization. 

Menger, F. M. Directionality of organic reactions in solution. Tetrahedron 1983, 39, 1013-1040. 

Drenth has since expanded these notes into a full-blown book (in Dutch) and has extended his coverage to 1994.188 Only just over a quarter of the book is devoted to the period up to 1970, while there is an exhaustive treatment of more modem times, with respect to the individual workers and institutions and the fields in which they have worked. Drenth has also unearthed biographical material on S. C. J. Olivier (1879-1961), who carried out pioneering work in the kinetics and mechanisms of organic reactions in solution from about 1912 to 1938.189 190For many years he was assisted by G. Berger (1892-1942). This work was mentioned in the monographs of Hammett,191 Waters,192 and Watson.193... 

Lim D, C Jenson, MP Repasky, WL Jorgenson (1999) Solvent as Catalyst Computational Studies of Organic Reactions in Solution. In Transition State Modeling for Catalysis, edited by D. G. Truhlar and K. Morokuma. Washington, DC American Chemical Society. 

Jorgensen WL (1988) Energy profiles for organic reactions in solution, Adv Chem Phys, 70 469... 

In the following, the emphasis will be on the first two parts of the problem, in particular, the potential of mean force (pmf) calculations that have been carried out in our laboratory for organic reactions in solution. The methodology is covered first and includes some details on trajectory calculations that have been carried out by others on related systems. Results of the pmf studies for representative 8, 2, Ad, and 8, 1 reactions are then reviewed. 

Yamataka, H. Theoretical calculations of organic reactions in solution. Rev. on Heteroa. Chem. 1999, 21, 277-291. 

---