Mass spectroscopy ketones

Peripentadenia is a monotypic genus of the family Elaeocarpaceae represented by Peripentadenia mearsii (C. T. White) L. S. Smith, a tree growing in rain forests of northern Queensland. Besides unidentified minor alkaloids, the species yields one major alkaloid, peripentadenine (49) (87). Its molecular formula, C22H34N203, was established by high-resolution mass spectroscopy the presence of phenol, ketone, secondary amide, and tertiary amine functionalities was deduced from examination of spectroscopic data. 

Williams, D.H. Budzikiewicz, H. Pelah, Z. Djerassi, C. Mass Spectroscopy and Its Application to Structural and Stereochemical Problems. XLIV. Fragmentation Behavior of Monocychc Ketones. Monatsh. Chem. 1964,95,166-177. 

ProbiMn 12.44 How could mass spectroscopy distinguish among the three deuterated forms of ethyl methyl ketone ... 

The mass spectroscopy clearly demonstrated that the oligomer molecule contained one butyl isopropenyl ketone unit at the chain end. The possibility that the ketone unit locates at the chain end of the polymer may be rejected because the low molecular polymer obtained in the lOmin polymerization also contained one ketone unit similarly to the high polymer. 

Subsequently, Tselinskii et al. found the dianion of Compound 2a to be stable and reacted it with a variety of electrophiles including picryl chloride, acetic anhydride, methyl iodide and vinyl ketone. They synthesized its dinitro derivative, dinitrodifurazano piperazine (2b) (DNDFP) [Structure (2.63)] by reacting the dianion (2a) with nitrogen oxide in CH3CN. The dinitro derivative which is quite reactive, was isolated by column chromatography and confirmed by mass spectroscopy [272]. 

Aldehydes and ketones generally give moderately intense signals due to their molecular ions, M+. Thus the determination of the molecular weight of a ketone by mass spectroscopy usually is not difficult. Furthermore, there are some characteristic fragmentation patterns that aid in structural identification. These are ... 

Ketones with branching in the a position may be anodically cleaved at a platinum electrode in CH3CN-LiC104 [38]. A mechanism was proposed that involved generation of carbenium ion on a cleavage of the ketone radical cation, analogous to reactions in photochemistry and mass spectroscopy ... 

Girard T or Girard P derivatives of cigarette MSS aldehydes and ketones were characterized my mass spectroscopy. 4-Nitrophenylhydrazine (4-NPH)... 

High-resolution mass spectra were obtained for unidentified compounds a, b, c, d, and f. The molecular formula of compounds a, b, c, and d is C12H22O. Proposed structures are isomers of ketones, e.g., a and b might be 2- or 4-isomers of ethylisopropyl cyclohexyl ketone and c and d might be cyclohex-4-ylhexan-2-one or cyclohex-4-yl-4-methylpentan-2-one, respectively. An unidentified compound (e) was found also for the quasi-molecular ion M + 1105. The only fragment was M - 18 in chemical ionisation mass spectroscopy. The molecular formula of unidentified compound f is C15H14O. The proposed structure is... 

Bicarbonate hydrolysis removed first the 11- and then the 12-substituent it was shown by mass spectroscopy that heudelottin E (18) had a formate at C-11, a 2-hydroxy-3-methylvalerate at C-12 and a 2-hydroxy-3-methylbutyrate at C-7. Heudelottin F (19) was acetylated in the side chain at C-12, while heudelottin C (20) was the 11-deformyl derivative of F. These compounds are of interest as they are the simplest ones containing the 11P-formyloxy-12oc-(2-hydroxy-3-methylvaleryloxy) system which has been found very commonly in the complex compounds of the prieurianin group. Acid treatment of heudelottin, like that of the simpler havanensin, very readily isomerises the oxide to a 15-ketone (22), but by alkaline hydrolysis of heudelottin it is possible to obtain the epoxy alcohol (17)... 

Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy were used to study the photo-oxidation of both poly(alpha-methylstyrene) (PMS) and polystyrene (PS) films which had been irradiated at different temperatures and with different radiation sources under an oxygen atmosphere. The oxidised films were treated with ammonia or sulphur tetrafluoride and photolysis carried out under vacuum. Photoproducts from both polymers were broadly similar, but aromatic ketone concentration was higher from the PMS and a new ketone was also identified from this source. Routes for formation of identified photoproducts are proposed. 13 refs. 

Information regarding the position of the substituents can be obtained from the mass spectra of the enamines of cyclic ketones. For instance in the case of the morpholine enamine of 3-methylcyclohexanone, which is shown to be a 2 1 mixture of/ and isomers by NMR spectroscopy, the fragmentation of the radical ion from the /) isomer results in the loss of a methyl radical from the C-3 position. The d isomer gives a complicated spectrum due to the loss of the hydrogen radical. 

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