Nitrobenzoyl peroxide

To determine the exact perbenzoic acid content of the solution, proceed as ftJlows. Dissolve 1 - 5 g. of sodium iodide in 50 ml. of water in a 250 ml. reagent bottle and add about 5 ml. of glacial acetic acid and 5 ml. of chloroform. Introduce a known weight or volume of the chloroform solution of perbenzoic acid and shake vigorously. Titrate the liberated iodine with standard 0-liV sodium thiosulphate solution in the usual manner. 

To obtain crystalline perbenzoic acid, dry the moist chloroform solution with a little anhydrous sodium or magnesium sulphate for an hour, filter, and wash the desiccant with a httle dry chloroform. Remove the chloroform under reduced pressure at the ordinary temperature whilst carbon dioxide is introduced through a capillary tube. Dry the white or pale yellow residue for several hours at 30-35° under 10 mm. pressure. The yield of crystaUine perbenzoic acid, m.p. about 42°, which is contaminated with a httle benzoic acid, is 22 g. It is moderately stable when kept in the dark in a cold place it is very soluble in chloroform, ethyl acetate and ether, but only shghtly soluble in cold water and in cold hght petroleum. 

is not always a safe criterion of purity. Benzoyl peroxide may be analysed as follows Dissolve about 0 6 g., accurately weighed, of benzoyl peroxide in 16 ml. of chloroform in a 350 ml. conical flask. Cool to — 6% and add 25 ml. of 0- IN sodium methoxide solution at once with cooling and shaking. After 5 minutes at — 5°, add 100 ml. of iced water, 5 ml. of 10 per cent, sulphuric acid, and 2 g. of potassium iodide in 20 ml. of 10 per cent, sulphvuic acid in the order mention with vigorous stirring. Titrate the liberated iodine with standard 0-lN sodium thiosulphate solution. 

The number of ethylenic linkages in a given compound can be established with accurate by quantitative titration with perbenzoic acid. A solution of the substance and excess of perbenzoic acid in chloroform is allowed to stand for several hours at a low temperature and the amount of unreacted perbenzoic acid in solution is determined a blank experiment is run simultaneously. 

Owing to the greater stabiUty and the easier preparation, monoperphthalic acid is genei y preferred to benzoic acid. 

Most of the methods for preparation of /3-naphthaldehyde have been given previously.2 A recent procedure describes the preparation of /3-naphthaldehyde from 2-bromomethylnaphthalene and hexamethylenetetramine in boiling acetic acid.3 The method of reduction of nitriles by stannous chloride was discovered by Stephen.4 

A 600-cc. beaker containing 100 cc. of water and equipped with an efficient stirrer, a thermometer, and a 200-cc. separatory funnel is immersed in an ice-water bath. When the temperature of the water has fallen to 0-5°, 10 g. (0.13 mole) of sodium peroxide (Note 1) is added. Then, with vigorous stirring, a solution of 37 g. (0.2 mole) of p-nitrobenzoyl chloride in 100 cc. of dry toluene is added dropwise over a period of about thirty minutes. After the mixture has been stirred for an additional one and one-half hours, the precipitate is filtered and washed with 200 cc. of cold water (Note 2). The yield of p-nitrobenzoyl peroxide is 28.5-29 g. (86-88 per cent of the theoretical amount). It melts at 155-156°. 

The product may be recrystallized most conveniently by dissolving it as rapidly as possible (Note 3) in 500 cc. of dry toluene 

In a parallel experiment in which 25 g. of sodium peroxide was used, the precipitate was not the peroxide but evidently consisted of sodium / -nitroperbenzoate. 

Excessive heating during recrystallization leads to extensive decomposition of the peroxide. 

---

The procedure described for the preparation of l-(m-nitro-phenyl)-3,3-dimethyltriazene is the method of Elks and Hey,2 and the preparation of m-nitrobiphenyl is also a modification of their procedure. The other principal methods for the preparation of m-nitrobiphenyl are the decomposition of N-nitroso-w-nitroacetanilide in benzene 3 and the decomposition of alkaline m-nitrobenzenediazohydroxide in benzene.4 Other methods that have been reported include the decomposition of potassium ire-nitrobenzenediazotate in benzene with acetyl chloride,6 the decomposition of m-nitrobenzoyl peroxide in boiling benzene,6 the decomposition of benzenediazonium borofluoride in nitrobenzene 7 at 70°, and the reduction of 4-(3 -nitrophenyl)-benzenediazonium acid sulfate in boiling ethanol.8... 

By a procedure similar to that described for />-nitrobenzoyl peroxide, the following peroxides have been prepared w-nitro-benzoyl peroxide (m.p. 136-137°) in 90 per cent yield anisoyl peroxide (m.p. 126-127°) in 86-89 per cent yields -bromoben-zoyl peroxide (m.p. 144°) in 73 per cent yield and 3,4,5-tribromo-benzoyl peroxide (m.p. 186°) in 40 per cent yield.1 The procedure is not satisfactory for preparation of acetylsalicylyl peroxide, which is more conveniently prepared by action of hydrogen peroxide upon an acetone solution of the acid chloride. 

Nitrobenzoyl peroxide,2 as well as w-nitrobenzoyl peroxide2 and anisoyl peroxide,3 have been prepared in about 50 per cent yields from the acid chlorides and an acetone solution of hydrogen peroxide, in the presence of a basic substance such as pyridine, sodium acetate, or sodium hydroxide. w-Nitrobenzoyl peroxide has also been prepared by nitration of benzoyl peroxide with cold... 

The question of rearrangement in acyloxy radicals is still unsettled. In the case of the decomposition of -methoxy- -nitrobenzoyl peroxide rearrangement is observed, but the other circumstances indicate a polar mechanism for the reaction.118... 

Benzoyl peroxide appears to decompose entirely by the radical mechanism, the reaction being rather insensitive either to solvent changes or to the addition of acid catalysts. The unsymmetrical peroxide, -methoxy-/> -nitrobenzoyl peroxide, behaves quite differently. It will decompose either by the polar mechanism or by the radical mechanism.821 The radical mechanism prevails in benzene and the acids produced are -nitrobenzoic and anisic in equal amounts. In the more polar solvents anisic acid is formed to a lesser extent than is >-nitrobenzoic acid, because the carboxy inversion reaction (rearrangement) competes successfully. The reaction is subject to acid catalysis... 

Although benzoyl peroxide will initiate the polymerization (by a radical chain reaction) of either styrene or acrylonitrile, -methoxy- -nitrobenzoyl peroxide will not initiate polymerization efficiently in the latter monomer because it is too rapidly destroyed by the polar decomposition. Acrylonitrile, but not styrene, causes the polar decomposition to predominate, and the intermediates of the polar decomposition are not catalysts for the polymerization of acrylonitrile. 

A mixture of m- and p-nitrobenzoyl peroxide reacts with titanocene in THF solution to form the corresponding [(n -Cp)2Ti(02CC6H4N02)2] benzoate derivatives. The i.r. spectra of these compounds suggest that they involve unidentate carboxylato-groups. [(7i-Cp)2Ti(NCO)2] and [(7i-Cp)2Ti(NCS)2]... 

Acetylbenzoylperoxide and derivs 1 A54-A55 acetylbenzoylperoxide 1 A54—A55 acetylbenzylperoxide 1 A55 acetylbromide 1 A55 acetyl-(3-nitrobenzoyl)-peroxide 1 A55... 

Bis(nitrobenzoyl) peroxide See Di(nitrobenzoyl) -peroxide under Dibenzoylperoxide... 

Acetyl-(3 nitrobenzoyl)-peroxide or m-Nitro-benzoyl ocetylperoxide (called by Nef m-nitrobenzoylacetylhydroperoxyd), CH3.COr... 

Benzoyl peroxide (dibenzoyl peroxide), (CjHjCOO>2 (mp 104-106 °C dec), and /r-nitrobenzoyl peroxide (p-02NCgH4COO)2 (mp 156 °C dec), which is synthesized from p-nitrobenzoyl chloride and sodium peroxide [229], are rarely used as oxidants, and if so, they do not offer appreciable advantages over other organic oxidation agents. The anti addition of benzoyl groups to double bonds and the benzoxylation of aromatic rings are achieved in the presence of iodine [230], and alcohols are oxidized to carbonyl compounds in the presence of nickel dibromide [231],... 

---