Toluene mass spectrum

Figure 5.9 GALDI mass spectrum of natural rubber (from toluene/THF solution) on silver doped graphite matrix. The signal spacing of 68 Da corresponds to the isoprene monomer...

Fig. 11.3. Electron ionization and methane Cl mass spectra of toluene. The key features of the respective mass spectra are labeled. Spectral interpretation is based on recognition and understanding of these key features and how they correlate with structural elements of the analyte molecule of interest. The signal representing the most abundant ion in a mass spectrum is referred to as the base peak, and may or may not be the molecular ion peak (which carries the molecular mass information). Cl spectra provide confirmation of molecular mass in situations where the El signal for the molecular ion (M+ ) is weak or absent. The Cl mass spectrum provides reliable molecular mass information, but relatively little structural information (low abundance of the fragment ions). Compare with Fig. 11.4.

Fig. 11.4. Electron ionization mass spectrum of nonanal. Unlike the previous example (toluene, Fig. 11.3), this 9-carbon alkyl aldehyde displays extensive fragmentation and a very low abundance molecular ion at mlz 142. The extensive degree of fragmentation exhibited by many compounds under El conditions makes manual interpretation complex and tedious. Consequently, computerized searches of spectral libraries find extensive use in compound identification.

Fig. 19.8. Electron ionization mass spectrum of toluene (top panel) from GC-MS analysis, and library search match (bottom panel) against the NIST library.

Figure 1.9 FT-ICR mass spectrum of hot toluene extract produced by laser vaporization of a lanthanum oxide-graphite composite rod [66].

The reaction of diethylzinc with acetylacetone (acacH) in toluene resulted in the dimeric compound [EtZn(acac)]2 (39), which consists of a four-membered Zn202 ring . The El mass spectrum of 39 displayed three groups of peaks, attributed to the [Zn(acac)2] (miz 262), [EtZn(acac)] (m/z 192) and [Zn(acac)]+ (m/z 163) ions. The ion with m/z 192 simply represents a monomer fragment, whereas the ion with m/z 262 can be written as [M- EtiZn]. ... 

The H2-bme-daco is a pale yellow oil (may also be light pink) and is soluble in toluene, benzene, methanol, ether, and chloroform. The HNMR spectrum in CDC13 shows a quintet at 1.65, 4H, broad singlet at 2.15, 2H, a broad intense multiplet at 2.75, and a multiplet at 2.95, 4H. Mass spectrum m/z = 235. 

Fig. 6. An example showing the use of gas chromatography and mass spectrometry (GC-MS) for identifying reaction products on zeolites. Styrene was first reacted for ca. 30 min on activated zeolite HY at 298 K in a sealed glass tube the sample was extracted using toluene as solvent, and the extracts were then analyzed with GC-MS. The total ion chromatogram of the extracts (a) shows three major peaks eluting at 13.83, 13.93, and 14.31 min, respectively. The peak at 14.31 min was readily identified as the linear dimer. The peaks at 13.83 and 13.93 min show equal ion intensity and nearly identical mass spectra (the mass spectrum of the 13.93-min peak is shown in (b)), and these were assigned to the cis and trans isomers of the cyclic dimer.

Toluene Analysis by Gas Chromatography Estimate from Low-voltage Mass Spectrum... 

Specific examples illustrate that similar principles affect the absorption spectra. For example, as we have pointed out above, the neutral form of the C-2 benzyl ester is red in MeOH and orange in methylene chloride. Thus it has the spectrum of the ionized form in the polar, protic solvent and of the nonionized form in the nonpolar solvent methylene chloride [248]. The tributyl ammonium salt of the C-2 octyl ester is soluble in solvents ranging from ethanol-water to toluene. Its spectrum in an essentially nonionizing solvent such as toluene is that of the ionized xanthene [249], The spectrum of the pyrillium salt in ethanol is concentration dependent. In dilute solution the compound is totally ionized and is red, whereas in concentrated solution the compound is not fully ionized and the orange form predominates, as predicted by the law of mass action. 

A toluene solution of La Cs2 and l,l,2,2-tetramesityl-l,2-disilirane (13) was photoirradiated with a tungsten halogen lamp (cutoff <400 nm) (equation 7)17. The MALDITOF mass spectrum of the product shows the presence of La Cg2(Mes2Si)2CH2 (21). The EPR spectrum of the adduct (21) in 1,2,4-trichlorobenzene shows the presence of at least two species, presumably two positionally isomeric forms of the disilirane... 

The reaction of 3,4-benzo-l,2-disilacyclobutene (22) with Cgo yields the corresponding disilacyclohexane derivative (23)20. Irradiation of a solution of disilacyclobutene 22 and Cgo in toluene with a low-pressure mercury lamp (254 nm) afforded the brown adduct 23 in 14% yield (based on unreacted Cgo) (equation 8). The FAB mass spectrum of 23 exhibits one peak at m/z 1024-1027 (C7sH32Si2, M+, molecular cluster ion), as well as one for Cgo at m/z 720-723. The -NMR spectrum of 23 showed a symmetrical spectrum with two diastereotopic isopropyl methyl protons, one isopropyl methine proton and a AA BB pattern assigned to phenyl protons. The 13C-NMR spectrum of 23 shows 17 signals for the Cgo skeleton, of which four correspond to two carbon atoms each and 13 correspond to four carbon atoms each one signal appears at 63.93 ppm and the remainder between 130 and 160 ppm (Scheme 7, Figure 10). This pattern is consistent... 

The VOCs in the inside air are enriched by means of active sampling on Tenax TA tubes, which are thermodesorbed. After internal standards have been added, analysis is carried out by capillary GC—MS. The hundred compounds on the chromatogram which have the most intense signals are identified by retention index and mass spectrum (Wensing, Schulze and Salthammer, 2002), and are then semi-quantitatively evaluated with toluene as the reference substance. The toluene equivalents are summed, and this result serves as a semi-quantitative estimation of the total VOC concentration (TVOC). 

Figure 6. Simultaneous FT/ICR excitation/ejection of two ions of very similar mass-to-charge ratio, produced via electron ionization of toluene. In each plot, the heavy line represents the experimental FT/ICR mass spectrum, and the light line represents the magnitude-mode excitation spectrum used to produce that ICR signal. Top and 13c 2CgH7+ are excited with uniformly...

Orange crystals. 10.23 (toluene-d mass spectrum. X-Ray of Cl-compd. 175... 

The mass spectrum of cycloheptatrienetungsten tricarbonyl C7H8W (CO)3 (119) is very similar to that of the toluene analog, the only differences being that the cycloheptatriene complex exhibited the ions C6H6+ and C4H4+, which are not present in significant quantities in the spectrum of... 

By working at very high mass resolution, it was possible to study isotope effects on methyl loss from toluene and cycloheptatriene following El [32]. In the El mass spectrum, the intermolecular isotope effect ZcHj/ cd, was 1.12 in both cases (comparisons of C7H8 and C7D8). 

Photolysis of Cp Mn(CO)3 in THF leads to the solvent complex Cp Mn-(CO)2(THF). Removal of solvent at -20°C followed by warming to room temperature while maintaining reduced pressure results in dimerization of solvent complex, decarbonylation, and solvent loss to form the air-sensitive 8 (17,51,88). While not isolated, the related Cp complex 8 has been observed in the gas phase. It is seen, in the electron-impact mass spectrum of the THF complex CpMn(CO)2(THF), which shows a molecular ion and cracking pattern assignable to 8 rather than the THF complex itself (51). The rhenium complex 9 is formed on photolysis of Cp Re-(CO)3 in THF (18) and in the carbonylation (15-20 atm, THF or toluene) of Cp 2Re2(0)2(ju.-0)2 (89,90). 

A high abundance (70%) of C7HJ ions was also measured in the chemical ionization mass spectrum of toluene, where the CH and C2H ions were used as protonating agents, at a CH4-pressure of one torr (Munson and Field, 1967). 

Treatment of 2 with 3 equiv of 3-phenyl-2-propenal in refluxing toluene-cfe while the reaction progress was monitored by H NMR spectroscopy resulted in the disappearance of the aldehyde hydrogen peak (5 1.56). The IR spectrum of 4 shows a new absorption due to a vC-o stretch at 1448 cm 1. The mass spectrum of the product shows a molecular ion at m/z 538. To our surprise, an X-ray study of 4 showed it to be the insertion product of the two carbonyl ligands into the C-Si bond in 2. The reaction has the potential for developing a new method for double C-C bond formation between the carboranyl unit and carbonyl compounds. Such an insertion of the carbonyl functionality into the o-carborane has been observed in Yamamoto s work on the chemoselective addition of o-carborane to the aldehyde groups by a palladium-catalyzed9 or a fluoride-promoted reaction.10... 

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