Estimation of Dimerisation Constants from Complexatin-Induced Displacements of1H-NMR Chemical Shifts: Dimerisation of Caffeine

Autor:	Ian Horman, Bernard. Dreux
Rok vydání:	1984
Předmět:	Stereochemistry Chemical shift Dimer Organic Chemistry Enthalpy Biochemistry Catalysis Inorganic Chemistry chemistry.chemical_compound Monomer chemistry Drug Discovery Linear regression Proton NMR Physical chemistry Physical and Theoretical Chemistry Caffeine Compound c
Zdroj:	Helvetica Chimica Acta. 67:754-764
ISSN:	1522-2675 0018-019X
Popis:	The determination of the dimerisation constant (KD) for the weak self-association of a compound C in dilute solution according to the equilibrium, 2C⇌C2 is described. The method uses chemical shifts measured on a series of solutions of C at different concentrations: the optimum KD is defined by a linear regression best-fit procedure, which simultaneously determines optimum values for δo and also for δ∞, the intrinsic chemical shifts for nuclei in the monomer and dimer species. The dimerisation of caffeine in D2O is used as a model to demonstrate the working of the method and the quality of results obtained. The most probable value of KD for caffeine at 30.5° is found in the range 5.5–6.0 kg solution · mol−1, and the enthalpy and entropy of dimerisation are found to be ΔH⊖ = −15.1 kJ · mol−1 and ΔS⊖ = −35.3 J · °C−1 · mol−1, respectively. The influence of small errors in δo on the confidence limits of KD is discussed.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::ab2996dd34ca4b8e137d11bcc7b301c3 https://doi.org/10.1002/hlca.19840670316 Zobrazit plný text záznamu Plný text