Novel polyfluoroalkylated pyrazoles from 2-polyfluoroacylcycloalkanones and hydrazines: syntheses and unequivocal molecular structure assignment

2001 ◽  
Vol 79 (2) ◽  
pp. 183-194 ◽  
Author(s):  
D V Sevenard ◽  
O G Khomutov ◽  
M I Kodess ◽  
K I Pashkevich ◽  
I Loop ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Chain Length ◽  
Tautomeric Form ◽  
Ring Size ◽  
Polymethylene Chain ◽  
Structure Assignment ◽  
Substituted Hydrazines

The reaction between 2-trifluoroacetylcycloalkanones and methylhydrazine or phenylhydrazine exclusively yields 3-CF3-pyrazoles. When the chain length of the polyfluorinated substituent in RFC(O) group increases, 5-RF-pyrazoles are isolated. The reaction of 2-trifluoroacetylcyclohexanone with 2-hydrazinopyradine gives 5-hydroxypyrazoline, an intermediate in the formation of 5-CF3-pyrazoles. The regiochemistry of the condensation is probably controlled by the nucleophilicity of the terminal nitrogen in the mono substituted hydrazines and by the steric requirements of the RF group in the 1,3-diketones. Polymethylene chain containing pyrazoles obtained from the 1,3-diketones in question and hydrazine prefer the 3-RF tautomeric form, irrespective of carbocyclic ring size and polyfluoroalkyl group chain length.Key words: polyfluorinated 1,3-diketones, hydrazines, isomeric pyrazoles, molecular structure.

scholarly journals Impact of molecular structure on secondary organic aerosol formation from aromatic hydrocarbon photooxidation under low NO<sub><i>x</i></sub> conditions

2016 ◽  
Author(s):  
L. Li ◽  
P. Tang ◽  
S. Nakao ◽  
D. R. Cocker III
Keyword(s):  
Molecular Structure ◽  
Chemical Composition ◽  
Aromatic Hydrocarbon ◽  
Chain Length ◽  
Aromatic Hydrocarbons ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Ortho Position ◽  
Aerosol Formation ◽  
The Impact

Abstract. The molecular structure of volatile organic compounds (VOC) determines their oxidation pathway, directly impacting secondary organic aerosol (SOA) formation. This study comprehensively investigates the impact of molecular structure on SOA formation from the photooxidation of twelve different eight to nine carbon aromatic hydrocarbons under low NOx conditions. The effects of the alkyl substitute number, location, carbon chain length and branching structure on the photooxidation of aromatic hydrocarbons are demonstrated by analyzing SOA yield, chemical composition and physical properties. Aromatic hydrocarbons, categorized into five groups, show a yield order of ortho (o-xylene and o-ethyltoluene) > one substitute (ethylbenzene, propylbenzene and isopropylbenzene) > meta (m-xylene and m-ethyltoluene) > three substitute (trimethylbenzenes) > para (p-xylene and p-ethyltoluene). SOA yields of aromatic hydrocarbon photooxidation do not monotonically decrease when increasing alkyl substitute number. The ortho position promotes SOA formation while the para position suppresses aromatic oxidation and SOA formation. Observed SOA chemical composition and volatility confirm that higher yield is associated with further oxidation. SOA chemical composition also suggests that aromatic oxidation increases with increasing alkyl substitute chain length and branching structure. Further, carbon dilution theory developed by Li et al. (2015a) is extended in this study to serve as a standard method to determine the extent of oxidation of an alkyl substituted aromatic hydrocarbon.

scholarly journals REACTION OF NITRILIMINES WITH SUBSTITUTED HYDRAZINES: SYNTHESIS OF 1,2,4,5-TETRAAZA-3-PENTENES AND FORMAZANS

2011 ◽  
Vol 19 (19) ◽  
pp. 25-33
Author(s):  
Hany M. M. DALLONI
Keyword(s):  
Molecular Structure ◽  
Spectral Data ◽  
Activated Charcoal ◽  
Lithium Hydride ◽  
Substituted Hydrazines

A series of 1,2, 4, 5-tetraaza-3-pentenes 4a-j were synthesized by the reaction of appropriate nitrilimines 2 with substituted hydrazines (H2NNHCOR, R=Ph, OMe) 3. Heating the compounds 4a-j with activated charcoal in refluxing benzene oxidized to formazans 5a-j and some formazans 5fj (R = OMe) gave s-tetrazinones 6fj in presence of lithium hydride. The microanalysis and spectral data of the synthesized compounds are in fall agreement with their molecular structure.

Comparison between Molecular Structure Effects in Triplet Positronium Annihilation Rates and Radiolysis Free Ion Yields in Liquid Hydrocarbons

1972 ◽  
Vol 50 (16) ◽  
pp. 2697-2698 ◽  
Author(s):  
G. R. Freeman ◽  
J.-P. Dodelet
Keyword(s):  
Molecular Structure ◽  
Chain Length ◽  
Molecular Interaction ◽  
Half Life ◽  
Density Effect ◽  
Liquid Hydrocarbons ◽  
Positronium Annihilation ◽  
Free Ion ◽  
Alkane Chain ◽  
Ion Yields

Two seemingly unrelated phenomena in liquid hydrocarbons have similar trends in their dependences upon the molecular structure of the hydrocarbon. The phenomena are the annihilation half-life of triplet positronium and the radiolysis free ion yield. In n-alkanes the effect of increasing the molecular chain length, upon both phenomena, appears to be simply to increase the density of interacting sites. Branching the alkane chain decreases the strength of molecular interaction with both electrons and positronium, although the relative decrease is much greater for the former than for the latter. The effects of double bonds on the phenomena, after separating out the density effect, are different from each other.

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