Peroxide ethereal

Labour regulations have a code 19 with regards to the labelling of chemical compounds Can form explosive peroxides . Ethers with code 19 are listed in the table below ... 

When air was admitted after vacuum evaporation of a (peroxidic) ether solution of the dinitro compound (5 g), a violent explosion occurred. Exploding ether peroxide may have initiated the dinitro compound. 

It is evident that some leeway is available in the substituents tolerable in the m-position. The bronchodilator sulfonterol (28) is descended from this observation. Chloromethylanisole (29) is reacted with methylmereaptan to give 30, and the newly introduced group is oxidized to the methyl-sulfonyl moiety of 31 with hydrogen peroxide. Ether cleavage, acetylation and Fries rearrangement of the phenolic acetate produces 32, which is next brominated with pyrrolidinone hydrobromide tribromide and then oxidized to the glyoxal (33) with dimethyl sulfoxide. 

In our previous review, we attempted to establish some simple relationships among peroxides, ethers, alcohols and alkanes using a limited peroxide data set and a sometimes less than adequate data set for the comparison classes of compounds. The analysis is extended in this volume. The formal reactions, equations 2-5 and 6-9, that illustrate some typical comparisons are shown in Schemes 1 and 2. 

Polymeric Ethylidene Peroxide (Ether Peroxide) Extremely explosive, even below 100°C Eg, A. Rieche R. Meister, AngewChem 49, 101 (1936)... 

This ether forms peroxides on exposure to air in only a few hours.4,5 It can be stabilized by the addition of N-benzyl-p-aminophenol (16 ppm) or 50 ppm of diethylenetriamine, triethylenetetramine, or tetraethylene pentamine. Many examples of explosions of the peroxidized ether have been documented.4,6,7... 

A variety of other carbon-o gen groups have been suggested, including lactones, anhydrides, peroxides, ethers, and esters (14-18). These surfaces oxides have been studied by functional group reactions (18), titration, and infrared spectroscopy (15,... 

The formation of moderate amounts of methane throughout the flame probably indicates the presence of methyl radicals, but these do not appear to be the precursor of methanol (which is present in highest concentration along the boundary between the blue and smoky parts of the flame) since it is not a product in the diffusion flames of acetaldehyde or acetone, both of which should give rise to high concentrations of methyl radicals. One suggested source of methanol is through decomposition of the peroxidized ether radical, viz. 

Nitrogen peroxide. Ether solution at -20" C. Imido dihydroximio acid. I)inxj biui et, methyl mer-ciiric nitrate. Bamberger, Ber., 1899, 32, 3546 Bamberger and Miiller, Ber. 1899, 32, 3549. 

Purification of diethyl ether by aluminum oxide 14 Peroxidized ether is filtered through an upright column filled with activated aluminum oxide. This removes peroxides completely and reduces the water and aldehyde content of the ether. Filtration through a column 1.9 cm in diameter and 33 cm long, containing 82 g of aluminum oxide, removes peroxides completely from more than 700 ml of ether that contained 127 mmoles of oxygen per liter. 

Improvements to this route were made largely to eliminate using some of the hazardous or costly reagents such as high-strength peroxide, ether, and calcium and to permit the use of a flow sheet more suitable for large-scale production. 

Methyl Ethyl Ketone Peroxide Benzoyl Peroxide Ether Peroxides Peracetic Acid Potassium Metal Vinylidene Methyl Acetylene Cyclopentane... 

In this work, we develop a consistent set of oxygenated peroxy-hydrocarbon and acetylene-alcohol groups derived from the thermodynamic properties data of a set of hydroperoxides, peroxides, ethers and alcohols determined in previous chapters. 

Sym. acyl peroxides. Ethereal HgOg-soln. added at -15° to a soln. of phenyl-propiolic chloride in abs. ether, then pyridine added dropwise with stirring, which is continued 2 hrs. diphenylpropiolyl peroxide (Caution, explosive). Y 74.5%. C. Bischoff and K.-H. Platz, J. pr. 312, 2 (1970) also mixed acyl peroxides s. Do Linh Khuong, G. S. Bylina, and Y. A. OPdekop, Akad. Navuk Belarus. SSR, Ser. Khim. Navuk 1970 (3), 74 (Russ) C. A. 73, 87570. 

A peroxide is a compound with an O—O bond. Because an O—O bond is easily cleaved homolytically, a peroxide forms radicals that then can create new radicals—it is a radical initiator. Thus, the peroxide product of the preceding radical chain reaction can initiate another radical chain reaction— an explosive situation. To prevent the formation of explosive peroxides, ethers contain a stabilizer that traps the chain-initiating radical. Once an ether is purified (in which case it no longer contains the stabilizer), it has to be discarded within 24 hours. 

Addition of dilute potassium dichromate(VI) solution, K2Cr207, to a solution of hydrogen peroxide produces chromium peroxide, CrOj, as an unstable blue coloration on adding a little ether and shaking this compound transfers to the organic layer in which it is rather more stable. 

Ether so obtained is anhydrous, and almost entirely free from other impurities. On standing, however, it undergoes slight atmospheric oxidation, with the formation of traces of diethyl peroxide, (CaH jaOa. The formation of this peroxide can be largely checked, however, by storing the distilled ether over fresh sodium wire, preferably in the dark. 

Consequently traces of these unstable peroxides are present in samples of all the lower aliphatic ethers unless the samples have been freshly distilled. If these ethers when being distilled are heated on, for example, an electric heater, the final residue of peroxide may become sufficiently hot to explode violently. The use of a water-bath for heating, as described above, decreases considerably both the risk of the ether catching fire and of the peroxide exploding. 

Peroxides can usually be completely removed from a sample of ether by thorough shaking with aqueous potassium permanganate solution. 

Diethyl ether will be abbreviated throughout the book to ether. The ether should be reasonably free from peroxides, see Section 11,47,1. 

Absolute diethyl ether. The chief impurities in commercial ether (sp. gr. 0- 720) are water, ethyl alcohol, and, in samples which have been exposed to the air and light for some time, ethyl peroxide. The presence of peroxides may be detected either by the liberation of iodine (brown colouration or blue colouration with starch solution) when a small sample is shaken with an equal volume of 2 per cent, potassium iodide solution and a few drops of dilute hydrochloric acid, or by carrying out the perchromio acid test of inorganic analysis with potassium dichromate solution acidified with dilute sulphuric acid. The peroxides may be removed by shaking with a concentrated solution of a ferrous salt, say, 6-10 g. of ferrous salt (s 10-20 ml. of the prepared concentrated solution) to 1 litre of ether. The concentrated solution of ferrous salt is prepared either from 60 g. of crystallised ferrous sulphate, 6 ml. of concentrated sulphuric acid and 110 ml. of water or from 100 g. of crystallised ferrous chloride, 42 ml. of concentrated hydiochloric acid and 85 ml. of water. Peroxides may also be removed by shaking with an aqueous solution of sodium sulphite (for the removal with stannous chloride, see Section VI,12). 

Di-teo-propyl ether. The commercial product usually contains appreciable quantities of peroxides these should be removed by treatment with an acidified solution of a ferrous salt or with a solution of sodium sulphite (see under Diethyl ether). The ether is then dried with anhydrous calcium chloride and distilled. Pure di-iao-propyl ether has b.p. 68-5°/760 mm. 

CAUTION. Ethers that have been stored for long periods, particularly in partly-filled bottles, frequently contain small quantities of highly explosive peroxides. The presence of peroxides may be detected either by the per-chromic acid test of qualitative inorganic analysis (addition of an acidified solution of potassium dichromate) or by the liberation of iodine from acidified potassium iodide solution (compare Section 11,47,7). The peroxides are nonvolatile and may accumulate in the flask during the distillation of the ether the residue is explosive and may detonate, when distilled, with sufficient violence to shatter the apparatus and cause serious personal injury. If peroxides are found, they must first be removed by treatment with acidified ferrous sulphate solution (Section 11,47,7) or with sodium sulphite solution or with stannous chloride solution (Section VI, 12). The common extraction solvents diethyl ether and di-tso-propyl ether are particularly prone to the formation of peroxides. 

CAUTION. Acetals, like ethers, may contain explosive peroxides which must be removed before distillation is attempted. The procedure to be adopted is similar to that described under Ethers (see Section 111,60). 

Monoperphthalic acid. This is obtained by adding finely-powdered phthalic anhydride to a well-stirred solution of 30 per cent, hydrogen peroxide in alkali at —10° the solution is acidified and the per acid is extracted with ether ... 

The benzoic acid may be separated by steam distillation or by saturating the aqueous mixture of sodium salts with sulphur dioxide whilst maintaining the temperature below 40° the benzoic acid precipitates and can be separated by filtration or extraction with ether. Acidification of the filtrate with hydrochloric acid liberates the pyruvic acid. The pjTuvic acid may be oxidised < lth hydrogen peroxide to the arylacetic acid, for example ... 

Peroxide-free ether should be employed for detection and removal of peroxides in diethyl ether, see Section 11,47,i. 

Note 2. A very vigorous explosion has occurred in our laboratory in the course of a distillation of a large amount of the propargyl ether, which had been stored for 3 weeks at room temperature. Traces of peroxide (the product had not been kept under nitrogen) might have been responsible for the explosion. In any case it is not advisable to distil large quantities of propargyl ethers at normal pressure. 

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