Demethylations of quaternary pyridinium salts by a soft nucleophile, triphenylphosphine. Electronic and steric accelerations

Berg, Ulf; Gallo, R.; Metzger, Jacques

doi:10.1021/jo00877a023

Cited by 47 publications

(19 citation statements)

References 4 publications

(6 reference statements)

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“…The increase in DMC and tributylamine indicated that dealkylation of the quaternary was also a significant thermal degradation pathway. This thermal dealkylation is similar to that proposed by Berg et al [20] for aromatic quaternary iodides in DMF.…”

Section: Thermal Stability Of Tbq Mc/hcsupporting

confidence: 89%

Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Weisshaar

Earl

Amolins

et al. 2011

J Surfact & Detergents

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Quaternary ammonium compounds are used commercially for a variety of applications and some are of interest as ionic liquids. For many years dimethyl carbonate has been touted as a green reagent, including its use for methylation (quaternization) of tertiary amines. In addition, substitution of the methyl carbonate by other anions can be efficiently and cleanly accomplished by reaction with the corresponding acid. How stable are these methyl carbonate quaternary compounds? High field 13 C NMR shows that in the presence of water, the methyl carbonate is converted to bicarbonate. Headspace GCMS indicates that the alkylammonium methyl carbonate salts are stable below 170-180°C while the bicarbonate salts are stable to only about 140°C. Thermal decomposition occurs by decarboxylation and by dealkylation.

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Section: Thermal Stability Of Tbq Mc/hcsupporting

confidence: 89%

Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Weisshaar

Earl

Amolins

et al. 2011

J Surfact & Detergents

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“…The specific rates of the Menschutkin reaction of methyl iodide with 2-(and 6-) substituted pyridines show similar deviations from the Bransted correlation of "unhindered" bases; this deviation has been assigned to steric effects (26,27) and quantitatively correlated with steric parameters (28). simply the experimental value of the rate constant for the particular "hindered" base, and k,rcd,,lc, is given by log kprcdiclcd = B p~: f C, where pK: refers to the same "hindered" base and p and C are obtained from the Bronsted plot of log k vs. pKi for the "unhindered" bases; S F is thus conveniently given by…”

Section: Figmentioning

confidence: 94%

Vinylogous nucleophilic catalysis. Tertiary amine promoted hydrolysis of 1-alkene-1-sulfonyl chlorides

King¹,

Hillhouse²,

Skonieczny³

1984

Can. J. Chem.

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This paper is dedicated to Professor Paul de Mayo on the occasion of his 60th birthday JAMES FREDERICK KING, JOHN HENRY HILLHOUSE, and STANISLAW SKONIECZNY. Can. J. Chem. 62, 1977Chem. 62, (1984. We present evidence that the reactions of ethenesulfonyl chloride ( I ) and trcrt~s-l -propene-l -sulfonyl chloride (3) with water in the presence of pyridine, trimethylamine, and a number of other tertiary amines proceed primarily by way of an initial + vinylogous substitution reaction to form the cationic sulFne, R.;NCHRCH=SOZ. which subsequently reacts with water either by addition (and deprotonation) to form the betaine R.;NCHRCHZSOI, or by vinylogous substitution (and deprotonation) to give the alkenesulfonate anion. CHR=CHSO, (R = H or CH3). Formation of,the latter represents the first well-supported example of vinylogous nucleophilic catalysis. These conclusions are drawn from kinetic and product composition observations, including ( ( I ) a-monodeuteration in the betaine and lack of deuteration of the ethenesulfonate (CHZ=CHSO,) from the reaction in DZO, fb) rate lowerings of up to 2000-fold for 2-(and 6-) substituted pyridines from those expected from Bronsted-type relationships shown by "unhindered" pyridine bases, (c) lack of a kinetic solvent isotope effect in the reaction of 1 with 3-cyanopyridine, (d) a lower rate of reaction of 3 vs. 1 not directly correlated with product composition, and (e) formation of similar product mixtures from either 1 or Pyr'CHZCHZSOZCI CI- (180) with aqueous pyridine. For the initial + formation of the sulfene, R3NCHZCH=SOZ, the available evidence does not distinguish between a two-step mechanism via an intermediate zwitterion and a closely related concerted reaction, but for the further reaction of the sulfene a process involving a zwitterionic intermediate common to both products is favoured. For the reaction of 1 or 3 in the absence of tertiary amines evidence is presented for a direct displacement on sulfur mechanism leading to the alkenesulfonate anion, plus a small proportion (up to 15%) of formation of the 2-hydroxy-I-alkanesulfonate anion by way of the sulfene HOCHRCH=SOZ (R = H or CH3).JAMES FREDERICK KING, JOHN HENRY HILLHOUSE et STANISLAW SKONIECZNY. Can. J . Chem. 62, 1977Chem. 62, (1984. On rapporte des donnCes qui suggkrent que la rCaction du chlorure d'6thknesulfonyle ( I ) et du chlorure de propkne-l sulfonyle-l trans (3) avec de I'eau, en prCsence de pyridine, de trimkthylamine et d'un certain nombre d'autres amines tertiaires, se produit principalement par le biais d'une rkaction initiale de substitution vinylogue conduisant i la formation du sulfkne cationique R;NCHRCH=SOZ, qui rkagit ensuite avec de I'eau soit par une addition (et une dCprotonation) pour former la bCtaYne R;NCHRCHZSO, soit par une substitution vinylogue (et une dCprotonation) pour donner I'anion alcknesulfonate, CHR=CHSO, (R = H ou CH3). La formation de ce dernier compose represente le premier exemple bien document6 d'une catalyse nuclCophile vinylogue. On tire ces conclusions en se basan...

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“…Recent data confirm the correctness of this argument. An unambiguous SN2 displacement of substituted pyridines from their quaternary salts is characterized by a ,Blg value of 0.39 (Berg et al, 1976).…”

Section: Vol 175mentioning

confidence: 99%

The necessity of magnesium cation for acid assistance aglycone departure in catalysis by Escherichia coli (lacZ) β-galactosidase

Sinnott¹,

Withers²

1978

Biochemical Journal

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1. Removal of Mg2+ from Escherichia coli (lacZ) beta-galactosidase slightly increases the rate of hydrolysis of galactosyl pyridinium salts, but decreases the rate of hydrolysis of arylgalactosides. 2. Fair correlation of logkcat. and log (Km) with the pKa of aglycone is now observed for arglygalactosides, as well as for glycosyl pyridinium salts. 3. Degalactosylation of Mg2+-free enzyme is the rate-limiting step in the hydrolysis of 2,4-dinitrophenyl galactoside. 4. alpha-Deuterium kinetic isotope effects for both sets of substrates are consistent with the rate-determining generation of a glycosyl cation. 5. The pH-independent, SNl hydrolysis of 3,4-dinitrophenyl galactoside has been measured: it is as fast as that of the galactosyl 3-chloropyridinium ion. 6. Hydrolysis of these two substrates by Mg2+-free enzyme proceeds at very similar rates. 7. It is concluded that loss of both types of aglycone takes place, without acid catalysis, from the first ES complex of substrate and apoenzyme. 8. Data for galactosyl azide and thiopicrate confirm that neither charge nor change of atom is the cause of the differences in behavior between aryl galactosides and galactosylpyridinium salts.

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Demethylations of quaternary pyridinium salts by a soft nucleophile, triphenylphosphine. Electronic and steric accelerations

Cited by 47 publications

References 4 publications

Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Investigation of the Stability of Quaternary Ammonium Methyl Carbonates

Vinylogous nucleophilic catalysis. Tertiary amine promoted hydrolysis of 1-alkene-1-sulfonyl chlorides

The necessity of magnesium cation for acid assistance aglycone departure in catalysis by Escherichia coli (lacZ) β-galactosidase

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