Sulfuric acid contraction

For the past year Strike had been in consultation with contract labs over the making of phenylisopropyl alcohols using sulfuric acid and allylbenzenes (don t ask). The lab owners would listen patiently as Strike primitively described how and why an OH should go on the beta carbon. And without exception, the lab owners would point out to Strike that the best way to get an OH on the beta carbon would be to put a Br there first. But Strike don t wanna put a Br there first Strike would say, Strike wants the OH put on directly using sulfuric acid " The lab guys had to do what Strike said because Strike was holding all the money (...a fool and her money etc.). But out of curiosity Strike asked how they would get that Br on the beta carbon. Every one of them said it was simply a matter of using the 48% HBr in acetic acid. They even showed Strike their stock solutions (usually from Aldrich or Fisher). 

Kubota and co-workers describe a novel oxidative rearrangement of the diosphenol (58) of 17iS-hydroxyandrost-4-ene-2,3-dione to the A-nor-A -1,2-diketone (59) in 33 % yield by the action of specially prep d manganese dioxide in boiling acetone. The rate of ring contraction is very sensitive to the source of the oxidant, and a trace of dilute sulfuric acid in the reaction mixture causes oxidative fission of ring A. 

Methyl 2,7- and 3,6-dimethyl-l//-azepine-1-carboxylate also show marked differences towards acid hydrolysis. The 3,6-dimethyl isomer, with 10% sulfuric acid at 20°C, forms the expected A,-(ethoxycarbonyl)-2,5-dimethylaniline in high yield (82%) however, the 2,7-dimethyl isomer requires more forcing conditions to effect ring contraction and yields a mixture of A-(methoxycarbonyl)-2,6-dimethylaniline (16% mp 103-105°C), A-(methoxycarbonyl)-2,3-dimethylaniline (1% mp 90-92°C), 2,6-dimethylphenol (1%), and 3,4-dimethylphenol (6% mp 66-67 C).115 A mechanistic rationale for these results has been proposed. 

Dimethyl 2,7-dimethyl-3//-azcpinc-3,6-dicarboxylate (39) rearranges in warm concentrated sulfuric acid to the pyridineacetate 40.247 Attempts to saponify the azepine diester with sodium hydroxide yielded only tarry products, whereas treatment with hot sodium methoxide resulted in ring contraction to the pyridineacetate 40, which crystallized from methanol with a higher melting point than the product from the acid-induced ring contraction.247... 

Total sulfuric acid. As specified by contract or purchase order... 

Following is a list of other pertinent refs which are currently classified as limited distribution 1) D.C. Coop et al, Modernization Program for Nitric and Sulfuric Acid Manufacture and Concentration at Alabama Army Ammunition Plant , Rapt No 8-67, Contract DAAA21-67-C-0864, C and 1 Girdler Inc, Louisville (1967) 2)E. Banik et al, A Study on... 

The naphthalene-derivatized seleno-ether macrocycles dinaphtho-[16]aneSe4> naphtho-[8]aneSe2 and naphtho-[12]aneSe3 have also been prepared. Hydrolysis of dinaphtho-[16]aneSe4 with sulfuric acid leads to formation of the ring contracted species naphtho-[8]aneSe2.103,104... 

Event 9 Fire/Explosion—Sulfur dioxide and sulfuric acid. Motiva Enterprises, LLC, Delaware City, Delaware (July 17, 2001). Collapse of a spent sulfuric acid storage tank (more than 250,000 gallons) triggered releases from nearby tanks, killed one contract worker, and caused a large fish kill. Other commonly bermed tanks were immersed in concentrated sulfuric acid for several days until they could be drained, but they did not fail ("News Link" Environmental 2008). 

A ring contraction [vide infra Scheme 161) or a ring opening of electrogenerated tetrahydro derivatives can be observed in sulfuric acid. 

Primary amino groups attached to the azepine ring are uncommon and behave atypically. For example, attempts to diazotize the 2-amino-3fT-azepine (111 X=Br) with sodium nitrite in 6M sulfuric acid failed (67JOC2367). Also, 3-amino-4-methyl-l//-1 -benzazepine-2,5-dione with sodium nitrite in acetic acid suffers ring contraction to the diazoquinolone (178) and not formation of the diazoazepinone as reported originally (75JOC3874). 

From Group 15 to Group 16. non-metallic behaviour takes over completely with no positive ions being stable. The + 6 state of sulfur is seen to have very poor oxidizing properties, and it is only in its concentrated form, and when hot, that sulfuric(VI) acid is a good oxidant. Hot concentrated sulfuric acid oxidizes metallic copper and is reduced to sulfur dioxide. The relative stabilities of the Se species with positive oxidation stales are considerably less than their S or Te counterparts, another example of the effect of the 3d contraction. 

Source Rieber, M. Okech, B. Fuller, R. "Sulfur Pollution Control The Disposal Problem" U.S. Bureau of Mines (Contract No. J0188144) Washington, D.C., July 1980 Volume 8, "Sulfuric Acid," Table 8.37, p. 8-89. 

This paper results from work completed in 1979 (and updated in 1980) to evaluate the emerging supply/demand, cost/price outlook for the fertilizer commodities phosphate rock, upgraded phosphates, sulfur, and sulfuric acid. Our purpose here is to publish, in part, our analysis of recent trends and events which impact on sulfur supply and demand, and to use these together with available production cost data to project price behavior for sulfur over the near term. Such projections are helpful to managers of large industrial firms as one of several tools available to them in making investment, contract, marketing, or other major decisions. This paper is necessarily limited in scope, and will attempt to summarize the world outlook with emphasis on the North American scene. 

Self-Test 15.2B When concentrated sulfuric acid and water are mixed, the total volume is less than the sum of the individual volumes before mixing. Explain this volume contraction in terms of intermolecular interactions. 

Flavones have been shown to suffer from a stereospecific ring contraction to give rra r-2-aryl-2,3-dihydrobenzo[ ]-furan-3-carboxylates upon treatment with phenyliodonium acetate, trimethyl orthoformate, and sulfuric acid (Equation 151) <2002T4261>. 

Ring contraction of a pyridazine with concurrent cyclization to indole derivatives proceeds with l-aryl-6-oxo-l,4,5,6-tetrahydro-pyridazines having at position 3 a carboxyl or methyl group (161). 137,186,707 reaction is usually performed in ethanolic solution containing hydrogen chloride or sulfuric acid, and also potassium hydroxide. Indoles of the general formula 162 (R2 = COOEt, COOH, or Me) are obtained. 

Both ring expansions and contractions are well documented. Ring size can strongly influence the course of the reaction. For example, Vogel found that the diol (20), obtained by reductive dimerization of cyclobutanone, cleanly rearranged to the ketone (21) on warming in dilute sulfuric acid (21) was subsequently used to prepare the novel pentalene (22 equation 14). 

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