Sulfuric acid reaction with epoxides

Write a mechanism for the reaction of 2-methyl-1,4-naphthoquinone epoxide (10) with sulfuric acid to form phthiocol. 

A modern example of an agent used against human fungal infections is Pfizer s fluconazole, which actually contains two triazoles. The first is added as the anion to an a-chloroketone and the second is added to an epoxide made with sulfur ylid chemistry (you will meet this in Chapter 46). Note that weak bases were used to catalyse both of these reactions. Triazole is acidic enough for even... 

Many terpenoids in the correct oxidation state having also an oxygen atom at C-2 are converted to carvenone (578) with sulfuric acid. The epoxide (563) of 3-carene also undergoes this reaction, yielding the (— )-isomer 578, the (+ )-isomer being obtained fix)m (- )-4-caranone (579). ° ... 

Reaction of epoxidized PBD with carboxylic acids gives access to hydroxy esters. The reaction can occur during the epoxidation of PBD with carboxylic peracids (vide infra). The reaction is acid-catalyzed and it should be no surprise that the reaction with acetic acid gives the hydroxyl ester if catalytic amounts of sulfuric acid are present (Scheme 16) [80]. 

Ester functions are not saponified under these ring opening conditions. However, a trans-a-acetoxy function hinders the epoxide opening reaction and a noticeable decrease in yield is observed in comparison to the cw-a-acetoxy isomer. The ring opening reaction is also dependent on the concentration of sulfuric acid. Polymer formation results when the acid concentration is too low and the reaction is markedly slower with excessive concentrations of acid. A 0.5% (vol./vol.) concentration of acid in DMSO is satisfactory. Ring opening does not occur when ethanol, acetone, or dioxane are used as solvent. 

A mixture of the epoxide ca. 5 mmol), sodium azide (6 g, activated by the method of Smith) and 0.25 ml of concentrated sulfuric acid in 70 ml of dimethyl sulfoxide is heated in a flask fitted with a reflux condenser and a drierite tube on a steam bath for 30-40 hr. (Caution carry out reaction in a hood.) The dark reaction mixture is poured into 500 ml of ice water and the product may be filtered, if solid, and washed well with water or extracted with ether and washed with sodium bicarbonate and the water. The crude azido alcohols are usually recrystallized from methanol. 

When two polymers interact or react with each other, they are likely to provide a compatible, even a miscible, blend. Epoxidized natural rubber (ENR) interacts with chloro-sulfonated polyethylene (Hypalon) and polyvinyl chloride (PVC) forming partially miscible and miscible blends, respectively, due to the reaction between chlorosulfonic acid group and chlorine with epoxy group of ENR. Chiu et al. have studied the blends of chlorinated polyethylene (CR) with ENR at blend ratios of 75 25, 50 50, and 25 75, as well as pure rubbers using sulfur (Sg), 2-mercapto-benzothiazole, and 2-benzothiazole disulfide as vulcanizing agents [32]. They have studied Mooney viscosity, scorch... 

The epoxidation of fatty acid methyl esters (FAME) is traditionally conducted in strong acidic media, e.g., with peracetic acid in sulfuric acid solutions. These reactions can be conducted by an environmentally benign route, however, in the... 

Pujo Boileau (Ref 1) studied the action of nitrogen peroxide on epoxides and found that the reaction did not yield nitro derivs, as expected, hut nitrate-nitrite esters metha-nolysis converted the esters to alcohol nitrates. Nitration with sulfuric-nitric acids (50/50) yielded dinitrate derivs and with... 

---