The Autooxidation of Organomercuric Salts

The title compound (I) was prepared by Diels-Alder reaction of butadiene-1,1,4,4-d., with ethylene. The considerations which led to the synthesis of I are presented and some examples are then given of how use of I can simplify the study of, and provide new information about, a number of different kinds of problems. In the proton magnetic resonance (n.111.r.) spectra of the products of additions to I , the tertiary protons ~~s~~a l l y appear as clearly defined quartets. Since J J a n ! can be read directly from these spectra, both the stereochemistry of the additions and the conforn~ations of the products call be deduced. Thus, oxymercuration of I is clear!y a traws addition and Na/Hg reduction of the mercury takes place with retention of c o n f i g~~r a t~o~l . \hihe11 the second step is performed in D.0, the oxyn~ercuration-reduction sequence represents a convenient route for the trans addition of DOH to a double bond. Deuteroboration provided a n example of cis addition of DOH to I. Acid-catalyzed hydration of I resulted in scrambling of the d e~~t e r i u~n atoms. The value of Gn,/o~f is small; Gur/on is 600 cal/mole. The position of the double bond in a product resulting from allylic substitution of I is determined by integration of the n.m.r. spectrum. lielative to I, the possibilities are no rearrangement, 50% rearrangement, and 100% rearrangement of the double bond. The first product of allylic substitution by N-bro~nosuccinimide shows IIO rearrangement; therefore, this reaction does 11ot require a "free" radical intermediate. The structure of an adduct formed during allylic acetosylation of I by mercuric acetate (the Treibs reaction) has been determined.

Section: Results a S D Discussionmentioning

confidence: 97%

CYCLOHEXENE-3,3,6,6-d₄ A USEFUL COMPOUND FOR THE STUDY OF MECHANISM AND STRUCTURE

Wolfe¹,

Campbell²

1965

“…In none of our experiments were we ever able to detect such an intermediate stage. ' Reduction of 3 with borohydride in ethanol/ tetrahydrofurane (7,12) yielded methyl pimarate indicating that no skeletal rearrangements had occurred in the formation of the organomercurial.…”

Section: Oxymercuration-demercuration Of Metlzylmentioning

confidence: 99%

Diterpene chemistry. IV. The oxymercuration–demercuration of methyl pimarate and methyl sandaracopimarate

ApSimon¹,

Krehm²

1969

The oxymercuration-demercuration procedure was explored for methyl pimarate and methyl sandaracopimarate. In the first case a dimercurial-monoether was obtained yielding a cyclic ether on demercuration. In the second, a monomercurial was obtained arising from attack on the vinyl group only, and demercuration gave a mixture of alcohols which were oxidized to a methyl ketone, which on hypoiodite degradation yielded a known degradation product of methyl sandaracopimarate. The difference in behavior between the two series is attributed to the proximity of the double bonds in methyl pimarate.CanadIan Journal of Chemistry, 47,2865Chemistry, 47, (1969 As part of our studies on pimaric l a and sandaracopimaric acid 2a (1, 2) we were interested in two aspects of their chemistry. Firstly we wished to epoxidize the vinyl groups preferentially in order to study their cleavage in the vicinity of the nuclear double bonds, and secondly we were intrigued by the interaction of the double bonds in pimaric acid as compared with sandaracopimaric acid, as evidenced by unusual oxidation products (1).Normal epoxidation of the parent acids or their methyl esters led exclusively to epoxidation of the nuclear double bond (3, 4), and attempts at bromohydrin formation (5) were inconclusive. Thus we felt that perhaps the oxymercuration procedure (6) would lead to preferential vinyl attack, and this process might also provide us some further information on the spatial interaction of the two double bonds in 1 (7). Oxymercuration-demercuration of MetlzylPirnarate l b Reaction of methyl pimarate l b with one equivalent of mercuric nitrate or mercuric acetate in aqueous t-butyl alcohol resulted in about 50% conversion to an oxymercurial isolated at its chloroderivative (see Experimental). When two equivalents of mercuric nitrate were used, about 90 % conversion was observed.The crystalline chloromercurial analyzed for C21H3203Hg2C12 m.p. 176", its infrared (i.r.) spectrum indicating no hydroxyl absorption but ester absorption was evident at 1726 cm The nuclear magnetic resonance (n.m.r.) spectrum showed no signals for olefinic protons. Assuming Markofinikov-type addition of the mercury salts (6) then these facts are best accommodated by structure 3. The n.m.r. spectrum of 3 supported the structural assignment as follows.Centered at 3.9 6 was a doublet of doublets characteristic of the X branch of an ABX system with JAx 6 Hz and JBx 11 Hz which we assign to the H-15 proton of 3. At 3.0 6 there was a weakly coupled singlet (J 0.2 Hz) which we assign to. H-14P appearing at a lower iield than the C-16 protons since it is both tertiary and will be affected somewhat by the proximate ether bridge. The coupling observed is probably due to W-plan coupling (8) with the 12P proton.The stereochemistry at C-14 is assumed since the intramolecular attack on a mercurinium ion (6, 9) at C-8 and C-14 must come from the opposite face than the mercury (lo), and the stereochemistry of pimaric acid fixes the direction of attack from the p face by the two carbon Can....

“…Thus sufficient mercury to satisfy eq. [7] is soon present and added inetal is superfluous. The ready evolution of the metal may be due to the peroxide-forming tendency of nitrate (and nitrite) salts.…”

Section: I61mentioning

confidence: 99%

“…Since the present study excludes this type as the direct catalyst, we suggest that metallic mercury is formed according to [9]-[ll.] because the RHg+ cation will be unstable (7). Since mercuric halide is potentiall).…”

Section: I61mentioning

confidence: 99%

The Redistribution Reaction of Bis-Mercurials

French¹,

Inamoto²,

Wright³

1964

Self Cite

The de~netalation of diorganosubstituted mercury con~pounds is catalyzed by peroxides. When organonlercuric salts are present this demetalation leads to formation of mercurous salt plus mercury. This latter combination has been found to be a catalyst for the redistribution reaction of bis-mercurials. I t is suggested that all previously reported catalysts for this reaction operate by formation of the mercurous salt -mercury combination. Equilibration studies with this co~nbinatioll a s catalyst indicate that random exchange is not general for the redistribution reaction of mercury compounds.The equilibration of organic substituent groups among mixtures of bis-organolead, organotin, and organomercurials has been summarized (1) by Calingaert, who coined the name "redistribution reaction" originally for the equilibration of tetraalkyllead compounds in which the substituents were homologous or structurally isomeric (2). He applied the name also to the simpler equilibration of bis-mercurials (3).Obviously these reactions are, a t most, "distributions"; the redundancy was unfortunate but a t least it accentuated Calingaert's discovery that the "redistribution" was statistically random and unrelated to the structure of the substituent groups. Also, he demonstrated t h a t the redistribution was catalyzed by metal halides and organometallic halides, including those related to the organometallic compounds that he was "redistributing".Despite the mass of evidence relating to the redistribution reaction and its catalysis, we have found that for bis-mercurials i t is quite erratic. For example, 4-cyclohexylmercuritoluene is recovered unchanged when it is treated in solvents such a s methanol, petroleum ether, benzene, or dioxane with 1-5 inole % of the recommended (3) catalysts: boron fluoride etherate, aluminum chloride, magnesium bromide hydrate, zinc chloride, and cyclohexylmercuric chloride a t room temperature. On the other hand, a moderately pure sample decomposes when heated without either solvent or any of the recommended catalysts, giving bis-4-tolylinercury. Likewise, for one operator, 2-butylmercuri-4-toluene in inethanol or petroleum ether has been heated under reflux for 15 h without alteration in presence of mercuric bromide or 2-butylmerc~iric bromide. For another, a methanol solution of the substance has reacted in 8 h under reflux without added catalyst to give a 42Yo yield of bis-4-tolylinercury and a 47Yo yield of bis-2-butylmercury. Similar anomalies have been found for benzylinercuriethane.Part of the reason for this lack of reliability has become evident during our attempts to isolate and preserve bis-cyclohexyln~ercury in a pure state for determination of its dielectric constant (4). T h e instability of this substance is apparent in its use (5) a s a catalyst in the hoinopolar polyn~erization of vinyl acetate. We find that the recently crystallized white substance turns grey within a n hour in air. If it is vacuum distilled immediately after crystallization, some decomposition occurs during t...