Trimethylamine, ionization

Figure 25. Ion mass peaks at different two-photon energies. Broadenings of trimethylamine (TMA ) ion peaks as a function of the ionization energy. A hv2 > 3.875 eV B hv2 = 3.688 eV C hv2 = 3.607 eV. Excitation energy of paraxylene (PX) in the Si state = 3.90 eV. The broadenings in B and C correspond to time constants of 160 20 and 200 20 ns, respectively. Peaks corresponding to TMA H+ are also observable. Taken with permission from Int. J. Mass Spectrom. Ion Proc. 1994, 131, 233-264.

As expected, DABCO is a much stronger base than triethylamine, has two ionization potentials separated by several electron-volts, and is more easily oxidized than trimethylamine. What is unusual about DABCO is that the in-phase combination of the nonbonded pairs is the HOMO, the lowest IP is lower than that of trimethylamine, and the next higher IP is higher than that of trimethylamine. Explain. 

The cationic polymerization was further evidenced by studying the effect of added proton scavengers, such as ammonia and trimethylamine, and the copolymerization with a-methylstyrene and isobutylvinylether. It is now believed that both radical and cationic polymerization of styrene are able to proceed by ionizing radiations even in bulk at room temperature, and the latter polymerization is much more predominant in the absence of cation scavengers, though it is effectively suppressed in their presence. 

Cations having a tetracoordinate silicon may appear by three general routes. Apart from the ionization of a silicon-reactive ligand bond, the cations can be formed by transformation of a group bound to silicon, in particular by the addition of positively charged ion. For example, the quaternization of trimethylsilylamine with methyl iodide leads to the same ionic complex as the reaction of trimethylsilyl iodide with trimethylamine [Eq. (46)] (254). 

Basran, J., Sutcliffe, M. J., Hille, R., and Scrutton, N. S., 1999a, Reductive half-reaction of the H172Q mutant of trimethylamine dehydrogenase evidence against a carbanion mechanism and assignment of kinetically influential ionizations in the enzyme-substrate complex, Biochem. J. 341 3079314. 

The reason for this difference is not yet obvious, nor is it clear whether this is a general phenomenon. In fact, an opposite trend was reported for the styrene-trimethylamine system [27], In any case, the difference in ionization efficiency may become another tool for studying gas-phase systems. In cases where several R-isomers co-exist in the jet, some differences were recorded in their photophysical behavior. The change in the rate of R E isomerization was found to depend on the internal energy in a different way. However, the differences were in general small. 

An attempt to establish the role of exciplexes in a reactive system was made by Kendler and Haas [27]. The fluorescence characteristics of the styrene-trimethylamine (TMA) adduct were studied in a supersonic jet. In the bulk, this system is known to exhibit exciplex emission and also to form photoproducts [42]. In the jet, fluorescence excitation of the STY-TMA 1 1 adduct revealed two isomers, an R-type and an E-type (Figure 9) (labeled n-type and w-type, respectively, in the original paper). The resonance-enhanced multiphoton ionization (REMPl)... 

Thousands of amines are known, and many are very important in biochemical processes. Low-molecular-weight amines are soluble weak bases. The ionization of trimethylamine, for example, forms trimethylammonium ions and OH ions. 

Ionization potential of Continued) butenone, 123 cyclic diacetylenes, 305 cyclohexene, 48, 102 cis-cyclooctene, 102 Zraus -cyclooctene, 102 DABCO, 81 dimethyl ether, 123 ethylene, 80, 319 formaldehyde, 123, 319 hydrogen atom, 55, 75 methanol, 123 methyl acetate, 123 methyl acrylate, 123 nitrous oxide (N2O), 172 norbornadiene, 48 norbornene, 48 oxetane, 123 tetrahydrofuran, 123 trimethylamine, 81 water, 123... 

Example 2-3 The liquid-phase reaction between trimethylamine and n-propyl bromide was studied by Winkler and Hinshelwood by immersing sealed glass tubes containing the reactants in a constant-temperature bath. The results at 139.4°C are shown in Table 2-2. Initial solutions of trimethylamine and n-propyl bromide in benzene, 0.2-molal, are mixed, sealed in glass tubes, and placed in the constant-temperature bath. After various time intervals the tubes are removed and cooled to stop the reaction, and the contents are analyzed. The analysis depends on the fact that the product, a quaternary ammonium salt, is completely ionized. Hence the concentration of bromide ions can be estimated by titration. 

TMADH showing ionizable residues and the aromatic bowl (Tyr-60, Trp-264 and Trp-355) that interacts with the three methyl groups of the substrate through amino-aromatic interactions. Residues His-172 and Tyr-60 play key roles in stabilising the trimethylamine... 

Chien, Y. C., Uang, S. N., Kuo, C. T., Shih, T. S., and Jen, J. F., Analytical method for monitoring airborne trimethylamine using solid phase micro-extraction and gas chromatography-flame ionization detection. Anal. Chim. Acta, 419, 73-79, 2000. 

In order to prepare the strong- or weak-base anion-exchange resins, the styrene-divinylbenzene copolymers are reacted with chloromethyl methyl ether, which converts the phenyl residues into benzyl chloride groups that are subsequently allowed to react with either secondary or tertiary amines. The chloromethyl groups supposedly become attached to the 4-position in the phenyl residues. Trimethylamine (Dowex-1, Amberlite IRA 400) and di-methylethanolamine (Dowex-2, Amberlite 410) are typical of the tertiary amines used in the preparation of commercial resins. The quaternary ammonium ion-exchange resins are highly ionized and can be used over the entire pYl range (14). 

Phospholipids have been studied by means of maity condensed-phase ionization techniques. In the FAB-MS mass spectra of GPCho, the three most abundant ions were [M+H]+, [M+Na]+, and a fragment ion [M+Na-59]+ due to the loss of trimethylamine. CID mass spectra with [M+Na]+ as precursor ion resulted in the loss of the fatty acids and the loss of choline phosphate, thus [M+Na-183]+,... 

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