O. S. Chizhov

Mass-spectroscopic study of compounds from the cyclopropane series 4. Behavior of the ethers under chemical ionization

1. A study has been made of the behavior of certain ethers under chemical ionization. 2. Breakdown of the quasimolecular ions of the ethers studied here gave rise to fragments characteristic of the ether and alkyl (aryl) groups and the cyclopropane ring. 3. The compounds in question could be separated into cis and trans isomers on the basis of a study of their CI mass spectra.

Polysaccharides of Lipomyces

1. A linear glucuronomannan was isolated fromLipomyces lipofer Strain 133, with α−1 → 3 and 1 → 4 linkages between the monosaccharide residues. 2. The α−D-glucuronic acid in the polysaccharide is linked to D-mannose by a 1→3 bond and, in turn, bears a substituent at C4. The linkage between the α-D-mannose residues is 1 → 4. 3. A linear structure was proposed for the given polymer on the basis of the data of the total hydrolysis and methanolysis of the methylated glucuronomannan obtained fromLipomyces lipofer Strain 133, the decomposition of its amide under the conditions of the Hoffmann reaction, and the data on the periodate oxidation of both the native and reduced polysaccharides.

Behavior of aromatic ortho esters under chemical ionization conditions

ConclusionsOrtho esters decompose under protolysis conditions in the gas phase to form carboxonium ions [MH-RHO]+, which can give stable associates with neutral molecules.

Protolysis of ortho esters and their analogs under conditions of chemical ionization

Conclusions1.The kinetic parameters of the dissociation of the ME+ ions of ortho esters and cycloalkanols under the conditions of chemical ionization were determined,2.The main direction of fragmentation in the MH+ ions of the ortho esters involves the elimination of a molecule of the alcohol. Here the degree to which this process occurs increases in the transition from the six-membered to the five-membered ortho ester and also with substitution of the OEt group (in the five-membered ortho ester) by the n-OC6H13 group. This is due to the reduction in the demands for the ordering of the transition state.

Mass-spectrometric study of compounds of the cyclopropane series. 9. Behavior of esters under electron impact

Conclusions1.The mass spectra of the cyclopropanecarboxylic acids and their methyl and ethyl esters exhibit rather strong intensity peaks of the molecular ions, the stability towards electron impact being greater for the methyl esters than for the acids, and the stability of the acids being greater than for the ethyl esters.2.Fragmentation of the studied compounds is accompanied by formation of the characteristic ions [M-H]+, [M-CH3OH]+, [M-CH3]+, and [M-55]+, the effect of the cyclopropane ring on the dissociation of the molecular ions being most clearly evident for the methyl esters.

Mass-spectrometric study of compounds from the cyclopropane series 7. The behavior of the cyclopropyl thioethers under electron impact and in chemical ionization

Conclusions1.A study has been made of certain aspects of the behavior of the cyclopropyl thioethers under electron impact (EI) and chemical ionization.2.The presence of the cyclopropane ring (CPR) gives rise to strong [M-alkene]+ ion peaks in the EI spectra of the aliphatic cyclopropyl ethers and [M-CH3]+, [M-C2H5]+, and [M-SH]+ ion peaks in the EI spectra of their aromatics analogs.3.The [M + H]+ ions of the aromatic cyclopropyl thioethers eliminate an ArH molecule.4.The presence of two Cl atoms in the CPR reduces the stability of the M+ and [M + H]+ ions, and largely determines their further fragmentation.

Mass spectroscopic study of compounds from the cyclopropane series 6. Behavior of alkyl and aryloxy gem-dichlorocyclopropanes under chemical ionization

Chemical ionization mass spectra have many advantages over electron impact mass spectra in studying the alkyl and aryloxy gem-dichlorocyclopropanes. Most of these compounds gives highly stable quasimolecular ions and the products obtained from decomposition of the latter furnish more complete information concerning molecular structures.

A mass spectroscopic study of compounds from the cyclopropane series. 3. Behavior of alkoxy- and aryloxy-gem-dichlorocyclopropanes under electron impact

1. The principal direction of alkoxy-gem-dichlorocyclopropane M+ ion breakdown is that leading to the formation of gem-dichlorocyclopropyl ions, and the alkyl ions resulting from their decomposition, together with rearranged fragments with m/e 90, 91. 2. Under electron impact, the aryloxy-gem-dichlorocyclopropanes give aromatic gem-dichlorocyclopropyl fragments, together with the ions, ArO+, ArO+, [M-Cl]+, [M-Cl, -CO]+, and [M-Cl, -HCl, -CO]+ ions. 3. Conditions favoring and inhibiting these various processes have been given.

A mass-spectroscopic study of compounds from the cyclopropane series 5. Electron-impact and chemical-ionization mass spectra of the geometrical isomers of alkyl- and vinyloxy-2-chlorocyclopropanes

1. A study has been made of the behavior of the geometrical isomers of the alkyl-and vinyloxy-2-chlorocyclopropanes under electron impact and chemical ionization. 2. Chemical-ionization methods can be used to distinguish the cis and trans isomers in this series of compounds, the quasimolecular and [M+H-alkene]+ ions being the more stable in the cis forms.