Characterization of alkane diol-CD complexes. Acid denitrosation of N-methyl-N-nitroso-p-toluenesulphonamide as a chemical probe

Celia Cabaleiro-Lago, Luis Garcia-Rio, Pablo Herves, Juan C. Mejuto, Jorge Perez-Juste

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

A study was carried out on the acid denitrosation of N-methyl-N-nitroso-p-toluenesulfonamide (MNTS) in mixed systems made up of linear (geminal and terminal) alkyl diols and beta-cyclodextrin (CD). The alkyl diols used allowed us to vary the length of the hydrocarbon chain from 2 to 6 carbon atoms. The observed rate constant, k(obs), decreases in the presence of CD. The inhibition profile decreases as the as the number of carbons in the chain is increased. This behaviour can be interpreted as a consequence of a balance between the complexation processes of MNTS and the alkyl diols by the CD. At a constant CD concentration and increase in the diols concentration decreases the concentration of free cyclodextrin available to complex with MNTS molecules and therefore produces an increases in the observed rate constant. The results were interpreted in terms of two different models; trough the presupposition and non-presupposition of a stoichiometry for the CD-diols complex. Both models agreed quite well and allow us to determine the uncomplexed cyclodextrin concentration in each case as well as the stoichiometry of the complexes. The binding constant for both types of alkane diols increase with increasing the number of carbon in the chain. Besides, the binding constant of the alpha,beta-alkane diols is higher than for the analog alpha,beta-alkane diols. One of the main consequences of this study is that the acid denitrosation of MNTS can be use to obtain the stochiometry of the CD-diol complexes and to monitor the free cyclodextrin concentration.

Original languageEnglish
Pages (from-to)209-216
Number of pages7
JournalJournal of Inclusion Phenomena and Macrocyclic Chemistry
Volume54
Issue number3-4
DOIs
Publication statusPublished - 2006
Externally publishedYes

Swedish Standard Keywords

  • Physical Chemistry (10402)

Keywords

  • beta-cyclodextrin
  • inclusion complexes
  • stability constant
  • uncomplexed cyclodextrin

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