Organic reactions enthalpy change

Oxidative addition of organic halides to cobalt, rhodium, and iridium centers is a fundamental reaction. Enthalpy changes for oxidative addition to Ir(I) have been evaluated by adiabatic titration calorimetric methods ... 

Standard state, for molecules, 24 687—688 Standard state enthalpy change for methanol synthesis, 25 305 Standard-state heat, 24 688 Standard-state heat of reaction, 24 688 Standards-writing organizations, 15 760 Standard Test Conditions (STC), 23 38 Standard test methods, 15 747—748 Standpipe pressure profiles, 11 818 Standpipes, in circulating fluidized beds, 11 817-819 Stand-retting, 11 606 Stannane, 13 613, 24 813... 

I) The selection of the enthalpy of adduct formation, as an approximation to the change in internal energy of the donor and acceptor upon addition compound formation, results from the thorough discussion by J. E. Leffler and E. Grunwald in Rates and Equilibria of Organic Reactions, New York John Wiley 1963. 

A//, the change in enthalpy, equals q, the heat transferred to or from a system at constant pressure A// = q. Since most organic reactions are performed at atmospheric pressure in open vessels. A// is used more often than is A . For reactions involving only liquids or solids A = A//. A// of a chemical reaction is the difference in the enthalpies of the products, Hp, and the reactants, // ... 

The calculated enthalpy change for this reaction is approximately 20 kJ mol-1. This result is of considerable consequence because it suggests that reduction of CO with a transition metal hydride, is not a useful route to organic products (see Fisher-Tropsch catalysis, page 715). 

Reproduced by permission from G. E Boyd, Thermal Effects In Ion-Exchange Reactions With Organic Exchangers Enthalpy and Heat Capacity Changes , in Ion Exchange In The Process Industries , Society of Chemical Industry, London, 1970, p. 261)... 

Note that because reactions in a bomb calorimeter occur under constant-volume rather than constant-pressure conditions, the heat changes do not correspond to the enthalpy change A// (see Section 6.3). It is possible to correct the measured heat changes so that they correspond to A// values, but the corrections usually are quite small, so we will not concern ourselves with the details of the correction procedure. Finally, it is interesting to note that the energy contents of food and fuel (usually expressed in calories where 1 cal = 4.184 J) are measured with constant-volume calorimeters (see Chemistry in Action essay on p. 215.) Example 6.3 illustrates the determination of the heat of combustion of an organic compound. 

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