Kinetics and linear free energy relationship of wittig reaction between substituted benzaldehydes and substituted benzylidenetriphenylphosphorane

Abstract The utilization of σ* constants for substituted phenyl groups converted from the known Hammett σ constants of the phenyl substituents is useful in assessing the linear free energy relationship (LFER) of the properties of various inhibitors. The inhibitors include thioketals, sulfenamides and N,N′thiobis(substituted formanilides). In the LFER of the rate of reaction between thioketals with 2-mercaptobenzothiazole, the rate is fastest when the thio group of the thioketal is attached to a substituted phenyl with the highest positive σ constant. The σ constant of alkyl groups is negative, and an alkylthio group gives a thioketal with a slower reaction rate. The LFER applies to the 13C NMR shift of the quaternary carbon of the thioketals with alkylthio groups. The slope of the linear relation is positive. However, changes in the 13C NMR shift of the arylthio derivatives are relatively small in spite of a wide variation in σ* constant. The LFER applies to the scorch delaying activities of all structural types of inhibitors in stocks accelerated by various benzothiazoles. In the linear relationship of scorch delay versus σ* constant in each type of inhibitor, the slope is negative. Variables with negative σ* constants give longer delay and those with more positive σ* constants give shorter delay. An exception is in the very fast curing MSSM/DPG stock where the thioketals from acetoacetanilide with arylthio groups give longer delay than the alkylthio compounds. In the TBBS-accelerated stock, the slopes of the linear relation of the carbamate sulfenamides, N,N′-thiobisformanilides and thioketals of cyanoacetanilides are about equal. However, the level of scorch delay obtained with the sulfenamides is significantly higher than the other two, which are equal in inhibition level. The inhibition action of N,N′-thiobisformanilides without alkylthio or arylthio groups is probably due to the formation of labile formanilide polysulfide intermediates.

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Equilibrium constants for a series of simple aldol condensations, and linear free energy relations with other carbonyl addition reactions

Canadian Journal of Chemistry ◽

10.1139/v78-162 ◽

1978 ◽

Vol 56 (7) ◽

pp. 962-973 ◽

Cited By ~ 60

Author(s):

J. Peter Guthrie

Keyword(s):

Free Energy ◽

Acetic Acid ◽

Carbonyl Compounds ◽

Equilibrium Constants ◽

Linear Free Energy Relationship ◽

Reaction Products ◽

Free Energies ◽

Linear Free Energy ◽

Energy Relations ◽

Relationship Of

A set of equilibrium constants for aldol condensations of acetaldehyde, acetone, acetophenone, and acetic acid as nucleophiles and formaldehyde, acetaldehyde, benzaldehyde, acetone, and acetophenone as carbonyl acceptors has been evaluated. The four values determined, directly or indirectly, by experiment have been augmented by values calculated from thermo-chemical data and equilibrium constants for enone hydration, and by estimation of free energies of formation of the reaction products by use of hypothetical disproportionation reactions. When the carbonyl nucleophiles are compared to other nucleophiles which can add to carbonyl compounds, it is found that they can be incorporated in the linear free energy relationship of Sander and Jencks, with γ values of 0.45 for acetaldehyde, 0.16 for acetone, 0.05 for acetophenone, and 3.56 for acetic acid. These results make it possible to predict the equilibrium constants for any of a large number of aldol condensations from the equilibrium constant for the addition of any nucleophile to the carbonyl accepter compound.

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Linear Free Energy Relationship Analysis of Solvent Effects on Singlet Oxygen Reactions

Current Organic Chemistry ◽

10.2174/1385272033486657 ◽

2003 ◽

Vol 7 (9) ◽

pp. 799-819 ◽

Cited By ~ 15

Author(s):

Else Lemp ◽

Antonio Zanocco ◽

Eduardo Lissi

Keyword(s):

Free Energy ◽

Singlet Oxygen ◽

Solvent Effects ◽

Linear Free Energy Relationship ◽

Relationship Analysis ◽

Linear Free Energy

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Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

Canadian Journal of Chemistry ◽

10.1139/v04-081 ◽

2004 ◽

Vol 82 (8) ◽

pp. 1294-1303 ◽

Cited By ~ 19

Author(s):

Vanessa Renée Little ◽

Keith Vaughan

Keyword(s):

Free Energy ◽

Chemical Shifts ◽

Linear Free Energy Relationship ◽

Piperazine Ring ◽

Linear Free Energy ◽

In Series ◽

Methylene Groups ◽

Diazonium Coupling ◽

The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

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Absorption Spectra of Substituted 2-Phenylindan-1,3-Dion-2-YL Radicals in Solution

Zeitschrift für Naturforschung A ◽

10.1515/zna-1983-1209 ◽

1983 ◽

Vol 38 (12) ◽

pp. 1337-1341

Author(s):

J. Zechner ◽

N. Getoff ◽

I. Timtcheva ◽

F. Fratev ◽

St. Minchef

Keyword(s):

Free Energy ◽

Absorption Spectra ◽

Flash Photolysis ◽

Bathochromic Shift ◽

Substitution Effects ◽

Linear Free Energy Relationship ◽

Linear Free Energy

Abstract Flash photolysis of a series of 2-phenylindandione-1,3 derivatives substituted in the 4′ position results in both the formation of stable benzylidenephthalides and of phenylindan-1,3-dion-2-yl radicals. The u. v. absorption maxima of these radicals are dependent on the solvent and show a bathochromic shift upon substitution. These substitution effects were correlated by means of a linear free energy relationship. Attempts were made to draw conclusions concerning the changes in the gap of the states involved and their curvature due to substitution.

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