The effect of benzene moiety fused with macrocyclic ring on the proton affinity of crown ethers studied in MS/MS experiment

• Autorzy: Frański R. , Gierczyk B.
• Języki publikacji: EN

Abstrakty

EN

In this paper we address the question how the presence of an aromatic moiety affects the proton affinity of crown ethers. In order to compare the proton affinities of crown ethers studied (M), we compared the abundances of protonated crown ethers ([M + H]+ ions) with the abundance of the ion [NH2-B15C5 + H]+ (formally also protonated crown ether). Both [M + H]+ and [NH2-B15C5 + H]+ were formed as a result of decomposition of [NH2-B15C5 + H + M]+. The presence of a benzene moiety fused with a macrocyclic ring strongly decreases the ratio [M + H]+/[NH2-B15C5 + H]+. Thus, the higher ring strain caused by the benzene moiety leads to a substantial lowering of the proton affinity of crown ethers. It is also suggested that for protonated benzocrown ethers the ring strain is partly compensated by the proton-đ interaction. The presence of an NO2 group decreases the electron density on the aromatic ring and, consequently, the proton-đ interaction is suppressed. As expected, the proton affinity of benzo-crown ethers increases with increasing size of their cavity since the ring strain is lower for larger molecules. An unexpectedly high proton affinity of dicyclohexano-18-crown-6 (DC18C6) has been observed.

Słowa kluczowe

EN

crown ethers; proton affinity; mass spectrometry

• Wydawca: Faculty of Chemical Technology and Engineering, University of Technology and Life Sciences, Bydgoszcz
• Czasopismo: Ars Separatoria Acta
• Rocznik: 2008
• Tom: No. 6
• Strony: 61--68
• Opis fizyczny: Bibliogr. 18 poz., rys.

Twórcy

autor

Frański R.

autor

Gierczyk B.

• Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6, 60-780 Poznań, Poland,

Bibliografia

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