The Reaction of Vinylmercuric Iodide with Nonhalogen Acid

Kreevoy, Maurice M.; Kretchmer, Richard A.

doi:10.1021/ja01066a028

Cited by 24 publications

(22 citation statements)

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“…The rate acceleration seen with cis-butenyl mercury substrate suggests partial protonation to stabilize a carbenium ion contributor. The stabilization by metals in carbenium ion intermediates has been explained to propose the ready acid protonolyses of alkenyl metal species (Kreevoy and Kretchmer, 1964;Negishi, 1980). In accord with a rate-limiting SE2 transition state is the solvent D20 Vmax isotope effect 20/VD20 of 2.1 for cis-butenyl-Hg j seen with the enzyme (Begley,Walts,Walsh,l986B).…”

Section: Mechanistic Proposalmentioning

confidence: 99%

Bacterial organomercury lyase: a protonolytic detoxification catalyst

Walsh¹,

Begley²,

Walts³

1987

Pure and Applied Chemistry

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Bacteria became resistant to organomercurials by enzyme-catalyzed protonolytic fragmentation of the C-Hg bond by the enzyme organomercury lyase to hydrocarbon and mercuric ion products. The gene encoding the enzyme has been subcloned, expressed, and the lyase purified to homogeneity and analyzed for specificity and catalytic mechanism. The retention of stereochemistry as endonorbornyl mercurial is converted enzymically in D20 to2endo-D1-norbornane and lack of other detectable radial pathways support an Sr pathway where C-H bond formation and C-Hg cleavage occur in a single transition state.

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Section: Mechanistic Proposalmentioning

confidence: 99%

Bacterial organomercury lyase: a protonolytic detoxification catalyst

Walsh¹,

Begley²,

Walts³

1987

Pure and Applied Chemistry

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“…With the exception of a few experiments in which NaNO, was added the electrolytes were various mixtures of HC10, and NaClO, . For p < 0.2M the results could be fitted to (2) [ 3 , 8 ] , by (2) log k, = log k,", + C p the method of least squares [9] with a slope, C, of 0.39, and an intercept yielding a value of 2.44 x 10-2M-1 sec-I for k i . The probable error of k k , so obtained, was f0.03 [9], and the average difference between experimental values of k , and those required by (2) was f20j,.…”

Section: Electrolyte Effectsmentioning

confidence: 99%

“…At higher electrolyte concentrations the increase in k , with p was less steep. Ignoring the results with ,u < 0.2M the data could be fitted to an equation of the same form as (2), but with parameters: k: , 2.54 x 10-2M-1sec-l, and C', 0.27. The average difference between experimental k , values and the predictions of the high-,u form of (2) (3) is f 2 % .…”

Section: Electrolyte Effectsmentioning

confidence: 99%

“…The average difference between experimental k , values and the predictions of the high-,u form of (2) (3) is f 2 % . The experimental points and the curves generated by (2) and (3) sec-l, respectively. (The uncertainties are average deviations from the mean.)…”

Section: Electrolyte Effectsmentioning

confidence: 99%

“…In previous papers [l-51 features of the mechanism of acidolysis of methyl [I], vinyl [2], and allylmercuric iodides [3-51 in aqueous solution have been reported.…”

Section: Introductionmentioning

confidence: 99%

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Cleavage of vinylic mercuric halides by aqueous acids

Kreevoy

Landholm

1969

Int J of Chemical Kinetics

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Isotope effects, general acid catalysis, and relative reactivities show that proton transfer to one of the unsaturated carbon atoms is rate determining for the acidolysis of unsaturated alkylmercuric halides. For compounds, R,R,C=CHHgX, substitution of CH, for H a t R, or R, leads to an acceleration of a factor of -30. This relatively small acceleration, the relative facility of the reactions, and the magnitude of the Br-catalytic terms, suggests an olefin-mercuric halide complex as the product of the rate-determining step, rather than a simple carbonium ion.T h e Brensted catalysis law is obeyed with a variety of carboxylic acids, giving an a of 0.69 & 0.04, but acids of other structures give substantially deviant catalytic coefficients, in a pattern similar to that generated by other A-SE2 reactions. T h e acetic acid catalytic coefficient is larger by a factor of 1C2 than that predicted if it were due to specific hydronium ion-general base catalysis instead of true general acid catalysis.T h e overall solvent isotope effect, k,/k,, is 2.55 f 0.10. The competitive isotoFe effect, K~/ K , , is 6.84 f 0.06. Taken with a model in which the proton is transferred directly from the H,O+ unit of the aquated proton to the substrate, these are sufficient to successfully predict the rate at all intermediate isotopic compositions.

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