RESUMO
The capabilities and performance of γ-titanium phosphate (γ-TiP) with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a latent thermal catalyst were investigated by the copolymerization of glycidyl phenyl ether (GPE) and hexahydro-4-methylphthalic anhydride (MHHPA) at different temperatures for a period of one hour. Polymerization was not observed until the reactants were heated to 100 °C. Upon increasing the temperature to 120 °C, the conversion in the presence of γ-TiP·DBU as a catalyst showed 98% conversion in 1 h. The thermal stability of GPE and MHHPA reacted in the presence of γ-TiP·DBU at 40 °C for 144 h resulted in less than 7% conversion of GPE. The conversion of GPE did not show a significant increase at 40 °C.
RESUMO
Cigarette smoke, a collection of many toxic chemicals, contributes to the pathogenesis of smoking-related diseases such as chronic obstructive pulmonary disease and cancer. Much work has been done on the chemical analysis of ingredients in cigarette smoke, but there are few reports on the active ingredients that can modify biomolecules. We used a sensitive liquid chromatography-mass spectrometry (LC/MS) and LC/MS/MS method to show that L-tyrosine (Tyr), an amino acid with a highly reactive hydroxyl group, readily reacts with cigarette smoke extract (CSE) at body temperature (37°C) to form various Tyr derivatives. Among these derivatives were N-(3-oxobutyl)-Tyr and two acetylated compounds, N-acetyl-Tyr and O-acetyl-Tyr, which were synthesized by reaction of Tyr with methyl vinyl ketone and acetic anhydride, respectively, at 37°C. The presence of methyl vinyl ketone and acetic anhydride in CSE was confirmed by gas chromatography-mass spectrometry (GC/MS). These results indicate that Tyr can easily react with active ingredients in CSE. The present analytical methods should aid the search for active ingredients in cigarette smoke.