SYNTHESIS OF 4’-ALLYLBENZO-3N-CROWN-N ETHERS AND THEIR MASS SPECTRA COMPARED WITH BENZO-3N-CROWN-N ETHERS

Abstract

Synthesis of 4’allylbenzo-3n-crown-n ethers was carried out by reacting demethylated eugenol with α,ω-dichloro-oligoethylene glycols in 1-butanol under basic condition. The mass spectra of 4’allylbenzo-3n-crown-n and benzo-3n-crown-n were investigated by mass spectrometry using electron impact under 70 eV of electron bombardment as ionisation method. The difference between the group of compounds is only the present of allyl moiety as a side chain at the other side of benzene ring. The first group consisting of four compounds (n= 4,5,6 and 7) are the products of synthesis from eugenol precursor while the reference consist of three compounds (n= 4,5, and 6). The mass spectra of the first group show m/z = 176 as the base peak except 4’allylbenzo-12-crown-4 base peak is the molecular ion with m/z= 264. Peak of m/z = 176 has the structure of stable 1,4-dioxane-like . The presence of allyl group at position 4 of the benzene ring show significant effect to mass spectra pattern especially to 4’allylbenzo-12-crown-4. While the three compounds of the second group gave m/z= 136 as the base peak. This ion has similar structure as 1,4-dioxane-like mentioned earlier. In general it can be said that the mass pattern of the studied compounds come from the cleavage of the polyether rings according to M-nx44, where mass of 44 is C2H4O (ethylene oxide-like). The allyl side chain is more stable than the polyether rings under the investigated ionisation. The same case happened to eugenol as well as to safrol where the base peak is the molecular ion.

Keywords: allyl-benzo-crown ethers, mass spectra, electron impact ionisation