Perchloric acid organic esters

In addition to the analysis of the thermal stability of the perchloric acid organic reaction media mixtures, a procedure was worked out to determine the fate of the perchloric acid by chlorine analysis of the batch, effluent streams, etc. Preliminary analyses on selected process samples showed no tendency for perchloric acid to concentrate in recycle material and therefore build up in the reactor. A total of less than 1% of the initial charge of perchloric acid (total chlorides calculated as perchloric acid) was found in the combined recovered acid-ester and olefin fractions. Less than 1 % of the initial charge of perchloric acid was found in the finished ester. The analytical method used was an oxygen bomb decomposition, followed by titration of chlorides with 0.0liV silver nitrate, using a recording automatic titrator. The eventual fate of the perchloric acid catalyst was... 

The corrosion behavior of tantalum is weU-documented (46). Technically, the excellent corrosion resistance of the metal reflects the chemical properties of the thermal oxide always present on the surface of the metal. This very adherent oxide layer makes tantalum one of the most corrosion-resistant metals to many chemicals at temperatures below 150°C. Tantalum is not attacked by most mineral acids, including aqua regia, perchloric acid, nitric acid, and concentrated sulfuric acid below 175°C. Tantalum is inert to most organic compounds organic acids, alcohols, ketones, esters, and phenols do not attack tantalum. 

Production of cellulose esters from aromatic acids has not been commercialized because of unfavorable economics. These esters are usually prepared from highly reactive regenerated cellulose, and their physical properties do not differ markedly from cellulose esters prepared from the more readily available aHphatic acids. Benzoate esters have been prepared from regenerated cellulose with benzoyl chloride in pyridine—nitrobenzene (27) or benzene (28). These benzoate esters are soluble in common organic solvents such as acetone or chloroform. Benzoate esters, as well as the nitrochloro-, and methoxy-substituted benzoates, have been prepared from cellulose with the appropriate aromatic acid and chloroacetic anhydride as the impelling agent and magnesium perchlorate as the catalyst (29). 

We conclude that the polymerisation of styrene by perchloric acid in methylene dichloride at 0 °C involves at least two types of independent propagating species. Rate studies and conductivity measurements, in conjunction with an independent study of molecular weight distributions [26, 27], indicate that these species include the perchlorate ester and the free polystyryl carbenium ion and that the term pseudocationic is a very appropriate description of what is a distinctive form of organic reaction. 

Bottles of HC104 should not be stored on wooden shelves, because acid spilled on wood can form explosive cellulose perchlorate esters. Perchloric acid also should not be stored near organic reagents or reducing agents. A reviewer of this book once wrote, I have seen someone substitute perchloric acid for sulfuric acid in a Jones reductor experiment with spectacular results—no explosion but the tube melted ... 

Lower members of the series of salts formed between organic sulfoxides and perchloric acid are unstable and explosive when dry. That from dibenzyl sulfoxide explodes at 125°C [1], Dimethyl sulfoxide explodes on contact with 70% perchloric acid solution [2] one drop of acid added to 10 ml of sulfoxide at 20° C caused a violent explosion [3], and dibutyl sulfoxide behaves similarly [4]. A fatal explosion resulted from mistakenly connecting a DMSO reservoir to an autopipette previously used with perchloric acid [5], (The editor has met a procedure for methylthiolation of aromatics where DMSO was added to excess 70% perchloric acid he did not feel justified in trying to scale it up.) Explosions reported seem usually to result from addition to excess sulfoxide. Aryl sulfoxides condense uneventfully with phenols in 70% perchloric acid, but application of these conditions to the alkyl sulfoxide (without addition of the essential phosphoryl chloride) led to a violent explosion [4]. Subsequent investigation showed that mixtures of phenol and perchloric acid are thermally unstable (ester formation ) and may decompose violently, the temperature range depending on composition. DSC measurements showed that sulfoxides alone... 

Hazards Wear gloves when handling 70% perchloric acid. 70% perchloric acid is very dangerous and may explode in contact with certain organic materials such as alcohols, ethers, esters, amines, and reducing agents. Use great care. 

A closely related variation of on-line SPE involves off-line removal of proteins prior to sample injection. Usually this procedure is accomplished by the addition of an organic solvent (e.g., acetonitrile) that contains an internal standard [63]. Variations of this strategy have been applied in our own laboratory for plasma bioanalysis [49] as well as in vitro screens [60]. A number of variations on this theme have often appeared in the literature for the simultaneous analysis of multiple analytes. An example of this type of analysis is described by Zell and co-workers, who used perchloric acid pretreatment prior to on-line SPE for the bioanalysis of a platelet inhibitor, its ester prodrug, and an active metaboUte [64]. Analytical ranges from 1 ng/mL to 1000 ng/mL are fairly typical for this technology, where most appUcations involve narrow-bore columns and begin with 50-100 juL plasma. Despite the need for a deliberate precipitation step, indirect SPE is generally more robust and less expensive than the other alternatives presented here. 

Salts and organic esters of some inorganic acids. In addition to the dangers of perchlorate salts, other salts such as nitrates, azides, diazo salts, organic nitrates, organic azides and picrates (see above) can be hazardous, and due care should be taken when these are dried. Large quantities should never be prepared or stored for long periods. 

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