Mass spectral properties

Infrared, electronic and mass spectral properties of azetidines are discussed in Sections 5.01.1.4-5.01.1.6. 

IR, UV and mass spectral properties of bicyclic azetidinones, other than penicillins and cephalosporins, have received thorough treatment (B-82MI51201). 

The mass spectral properties of 4-oxo-4A/-pyrido[l,2-a]pyrimidines with various degrees of saturation were studied by Tamas et a/.351,363... 

Table 1 Selected experimental derivatives and their corresponding melting points and mass spectral properties sPLA2 inhibitors. H NMR and IR analytical data supplied by author...

One communication has appeared which addresses itself to the mass spectral properties of organic azides. The mass spectrum of phenyl azide is reported to have a base peak at mje 91 corresponding to loss of a nitrogen molecule (M-28). This is followed by the loss of HCN to yield the C5H4 ion. The authors report that the spectrum is the same as that from benzotriazole. 

The chromato phic (TLC, i8.i . io,4i 1 gc,i and HPLC ) and polaro-graphic behavior and mass spectral properties - - of some pyr-rolo[2,l-i>]quinazoline alkaloids were investigated. A procedure for the rapid qualitative identification of vasicine (184) by means of capillary luminescence was developed. ... 

IV. ESTABLISHING THE MASS SPECTRAL PROPERTIES A. Choosing Ionization Polarity... 

Mass spectral properties of the generated anthocyanin derivatives were in line with data published for die isolated 4-vinylphenol and 4-vinylcatechol derivatives of malvidin 3-glucoside 8,15) and the tentatively identified 4-vinylguaiacol and 4-vinylsyringol adducts 14). The p-dimethylamino cinnamic acid product has not been reported before (Table... 

Table I. Mass Spectral Properties of the Generated Malvldin 3-glucoside Cinnamic Acid Derivatives...

Beside the main contaminants chlorobenzo(b)thiophene (one isomer) was also tentatively identified. Since reference material is commercial not available the identification based mainly on the gas chromatographic and mass spectral properties. First structural evidence for this compound was... 

During the GC/MS screening analyses several still unknown contaminants were detected. Consequently, structure elucidating analyses were performed on two different groups of compounds both appearing in the third extracts. Thus, polar and acidic properties have to be stated for these substances. The identification of the individual compounds was based mainly on the interpretation of their mass spectral properties and subsequent verification of the proposed molecular structures by synthesized reference material. 

The first group of contaminants comprises several isomers of mono- and dibrominated (methoxyphenyl)propionic acids. Their occurrence and isomeric distribution is illustrated in Fig. 2. All position isomers with respect to the methoxy group were present. However, for each methoxy substitution (2-, 3- and 4-substitution) only one isomer considering the bromination position was observed in most cases. Just one further monobrominated isomer was detected in the water samples which was not attributed to synthesized reference material. With respect to its mass spectral properties (as discussed above) the occurrence of a further 3-(bromo-2-methoxyphenyl)propionic acid methylester is likely. Interestingly, a very similar isomer pattern of reference substances was obtained by nonselective bromination of the corresponding nonhalogenated compounds (see also Fig. 5). Therefore, a technical preparation of these contaminants can be suggested. 

However, they represent a group of still unnoticed riverine contaminants, interestingly, substituted with bromine atoms. Thus, also structure elucidating analyses were performed on this substances. These compounds were identified by comparison of their analytical data with those of reference material in case of the mono-substituted contaminants. The identification of the dibrominated compounds is based on their mass spectral properties as well as on their gas chromatographic elution in comparison with the monobrominated compounds. In the following the mass spectral, gas chromatographic and IR spectroscopical properties are illustrated (Fig. 6 to 9) and discussed shortly. 

In 1970 the alkaloid was named cancentrine, assigned the novel structure 1, and since then publications describing some chemical transformations and mass spectral properties of cancentrine have appeared. In addition, two more alkaloids of the cancentrine type have been isolated from the same source. Brief reference has been made to the structure of cancentrine in Volume XIII of this series. This chapter is aimed at providing a review of the work done on the subject to date. 

Fig. 5. Some common denvatization methods to enhance mass spectral properties.

The mass spectral properties of the various derivatives of eicosanoids have been widely investigated with a view to structure elucidation of new metabolites and the use of GC-MS for their detection and quantification in biological tissues and fluids. The El spectra of the TMS derivatives are complex, although they contain abundant structure information, they exhibit relatively low abundance high mass fragment ions. In contrast the NICI spectra of the PFB derivatives are dominated by abundant [M — PFB]" anions, which allow low pico-gram detection limits to be reached in GC-MS-SIM. 

In the case of amphetamines, the dramatic improvement in mass spectral properties which can be obtained on derivatization is illustrated in Figure 11, which com-p)ares the fragmentation piattems of trifluoroacylated and heptafluoroacylated methamphetamine with that of the underivatized compound. 

Antonious, M. S. Mahmoud, M. R. Guirguis, D. B. Solvent polarity indicators mass spectral properties of some styryl pyridinium and quinolinium salts. Am. Chim. 1993, 83, 457 60. 

Derivatives of Diethylstilbestrol (DES), Mass Spectral Properties and Their Use in Biological Analysis... 

Of the two peaks eluted from the preparative t.l.c. plates only one (R 0.43) was amenable to GC-MS and this had a retention time of 8.5 min on an OV - 101 column at 240 with a helium flow rate of 40 ml/min. It was clear from the spectrum (Table 3) that the feprazone had been substituted with an oxygen (parent ion 336) but that the diphenylpyrazolidinedione nucleus itself had not been altered since m/e 183 and 252 were still present. It was concluded that the dimethylallyl side chain was the point of attack. Previous work on the metabolism of the dimethylallyl group suggested that a trans -alcohol was the most probable metabolite and accordingly this was synthesised and found to have identical chromatographic and mass spectral properties to the unknown. 

Two fern-9(l l)-ene derivatives, retigeric acid A (496) and retigeric acid B (497), have been isolated from lichens of the Lobaria retigera group 313). The structures were deduced from H-n.m.r. and mass spectral properties of the acids and derivatives and were confirmed by X-ray analysis of / -bromophenacyl retigerate A 314). 

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