Benzoyl Peroxide In Solution Research Articles

Stability of Benzoyl Peroxide in Aromatic Ester-Containing Topical Formulations

The chemical stability of benzoyl peroxide (BPO) was studied in solutions and gels. The solutions (1% w/v) were prepared in single solvents (alcohol USP, isopropyl alcohol USP, ethyl benzoate, C12–15 alkyl benzoate, dimethyl isosorbide, propylene carbonate, and acetone) and in binary and tertiary combinations of these solvents, with and without the addition of antioxidant(s) (BHT, BHA, eugenol, tert-butyl hydroquinone, Tenox-2™, vitamin E, and vitamin C). The solutions were stored at 37°C for 5 weeks, and each week were analyzed for remaining BPO. Using first-order kinetics, the stability of BPO in solution was found to decrease in the order: ternary >binary >single solvent systems. Regardless of the number of solvents present, the highest stability of BPO (t1/2 >7.5 weeks) was attained in the presence of ethyl benzoate and C12–15 alkyl benzoate. The stability of BPO in solution did not change significantly with the addition of most antioxidants. The solutions in which BPO remained most stable were one in alcohol USP-ethyl benzoate-C12–15 alkyl benzoate (60:20:20; t1/2 = 18.15 weeks) and another in alcohol USP-C12–15 alkyl benzoate-isopropanol plus 0.1% BHT (65:20:15; t1/2 = 12.44 weeks). In turn, these two solutions were converted to homogeneous gels by the addition of Cab-O-Sil™. The chemical stability of BPO in these gels was evaluated at 37°, 45°, 50°, and 55°C for 5 weeks. Parallel experiments were conducted with two commercial BPO products, a 2.5% tinted gel and 5% vanishing lotion. BPO was less stable in commercial products (t1/2 ≤ 13 weeks) than in the extemporaneously prepared gels (mean t1/2 ∼23 weeks). The present results suggest that aromatic esters can enhance the chemical stability of BPO in solutions and gel formulations to a significant extent.

The effects on radical polymerizations of some compounds containing double bonds involving nitrogen

The Schiff bases formed by condensation of aromatic aldehydes with aniline seem to induce the decomposition of benzoyl peroxide in solution. Benzaldehyde azine has very little effect of any type on the polymerization of methyl methacrylate. Benzaldehyde benzylamine is a retarder for the polymerization; the effect is much greater when benzoyl peroxide acts as initiator than when azobisisobutyronitrile is used. It has also been shown that azobenzene is a mild retarder for the radical polymerization of methyl methacrylate and that it has slight reactivity towards the benzoyloxy radical; the retarding effect is almost the same when using benzoyl peroxide as when the azonitrile is employed.

Benzoyl peroxide solubility and stability in hydric solvents.

Saturated solubility and reaction rate constants for the decomposition of benzoyl peroxide in solution and suspension were determined for use in formulation development. The solvents studied included ethanol, propylene glycol, and cosolvent mixtures of PEG 400 and water. The solubility of benzoyl peroxide was inversely related to the solvent polarity, with greater solubility occurring with semipolar solvents. The stability of benzoyl peroxide in solution was dependent on the solvent, concentration of benzoyl peroxide, and temperature. The compound was least stable in PEG 400. Stability was improved when water was added to PEG 400. Similar solvent effects were observed in suspension. In benzoyl peroxide suspensions of PEG 400 and PEG 400/water blends, benzoyl peroxide stability was dependent on solubility, with improved stability occurring in blends where the benzoyl peroxide was least soluble. Thus, solution formulations of benzoyl peroxide in pharmaceutically acceptable solvents are unlikely to show good stability; however, suspension formulations should be reasonably stable if the vehicle is selected to provide low benzoyl peroxide solubility.

Chemiluminescence method for determination of benzoyl peroxide in solution

The chemiluminescence reaction of benzoyl peroxide with triethylamine is used to quantify benzoyl peroxide. The method is rapid with a detection limit for benzoyl peroxide in chloroform of 0.07 μg ml −1 and a relative standard deviation of 4% at 1 μg ml −1. The technique is applied to the determination of benzoyl peroxide in pharmaceutical preparations.

Thermal decomposition of p-methyl-p'-nitrobenzoyl and bis-p-nitrobenzoyl peroxides

Differential enthalpic analysis was carried out below the melting point as well as at regular increases of temperature over the melting point of peroxides. From these measurements it follows that the thermal stabilities of peroxides in the solid state increase with their melting points. The rise in the melting point of the peroxide due to changed chemical structure is accompanied by a rise in the melting points of products which in turn affects the isothermal autocatalytic decomposition. The common feature of the thermal decomposition of the peroxides studied below their melting points is a very high apparent activation energy of the initiation of a chain decomposition reaction which is several times higher than that of a spontaneous thermal decomposition of peroxide in solution or in a melt of peroxide. p]From the study of the decomposition of nitro derivatives of benzoyl peroxide in solution it is known 1 that the electron attracting nitro-substituents have a retarding effect on the spontaneous decomposition of peroxides. The introduction which accompanies its thermal decomposition in solution 2. However not only the substitution of nitro groups in the molecule but also the presence of nitro compounds accelerates the decomposition of benzoyl peroxide 3. This indicates that the decomposition reaction may be influenced not only by an intramolecular rearrangement of electrons but also by an intermolecular interaction of nitro compounds with the peroxidic compounds or radicals generated by them. The substitution of methyl groups for hydrogen in aromatic rings does not produce any marked changes in the decomposition reactions of benzoyl peroxide 2. p]Among other changes produced by substitution, the physical changes—in particular, the changes in the melting points of investigated substances—are of importance to out study of the thermal decomposition of nitro derivatives of nitro derivatives of benzoyl peroxide. These data are interesting mainly because the decomposition of peroxides is influenced by the state of aggregation of the decomposing substances.

Studies on the Decomposition Reactions of Benzoyl Peroxide in Solutions. III. Reactions with Ethyl Aceotacetate, Diethy- and Dimethyl-Phenylmalonate.

過酸化ベンゾイルの分解機構を解明するため, 活性メチレン基, メチン基をもつ化合物を溶媒として過酸化ベンゾイルを熱分解させ, その反応生成物を調べた。アセト酢酸エステルを溶媒とするときは,過酸化ベンゾィルは遊離ベンゾキシ基のほか, かなりの量が遊離フェニル基に分解する。これら遊離基は溶媒分子のメチレン基より水素をとって安息香酸およびベンゼンとなり, 溶媒分子からの遊離基は二量化してジアセチルコハク酸エステルになる。フェニルマロン酸ヱステルを溶媒とするときは, 過酸化ベンゾイルは大部分二酸化炭素を放って遊離フェニル基に分解し, この遊離基は溶媒分子のメチン基に対しては脱水素反応を,ベンゼン核に対しては核置換反応を行う。脱水素反応による溶媒分子からの遊離基は二量化する。またベンゼン核置換反応はオルト位およびメタ位におこる。

Studies on the Decomposition Reaction of Benzoyl Peroxide in Solutions. IV-V. IV. Reaction with Ethyl Benzoylacetate and with Benzoylacetone.

過酸化ベンゾイルをベンゾイル酢酸エチルエステルおよびベンゾイルアセトン中で熱分解させ,その反応生成物を調べた。前者においては少量の二酸化炭素, ベンゼン, 多量の安息香酸の他,溶媒分子より生成したと考えられるジベンゾイルコハク酸エステル, 5, 12-ジオキシナフタセンキノン-(6, 11) および油状物を生成し, この油状物からは, 濃硫酸による処理, 加水分解でα, α'-ジェニルフラン-β, β'ル-ジボン酸が得られる。後者においては二酸化炭素の生成は非常に少なく,過酸化ベンゾイルの大部分は安息香酸となる。その他にはジベンゾイルジアセチルエタン, フラン誘導体および油状物が生成する。ジベンゾイルジアセチルエタンは酸で処理するとフラン誘導体を与えるが, これはさきのフラン誘導体の異性体である。これら生成物から過酸化ベンゾイルの分解機構を推論した。

Studies on the Decomposition Reaction of Benzoyl Peroxide in Solutions. IV-V. V. Rates of Decomposition Reaction of Benzoyl Peroxide in the Solvents which have active Methylen or Methin Group in the Molecule.

フェニルマロン酸ジメチルエステル, マロン酸ジエチルエステル, アセト酢酸ヱチルエステル,ベンゾイル酢酸エチルエステル, ベンゾイルアセトンおよびマロン酸ジエチルエステル-ベンゾイルァセトン, マロン酸ジエチルエステル-ジベンゾイルメタン混合溶媒申の過酸化ベンゾイルの分解速度を77℃にて測定し, その結果に考察を加えた。

The decomposition of benzoyl peroxide in solution at high pressures

The first page of this article is displayed as the abstract.

Effect of phenols on the rate of decomposition of benzoyl peroxide.

THE decomposition of benzoyl peroxide in solution occurs by unimolecular fission into two radicals : In ‘reactive’ solvents (SH) this is accompanied by an induced chain-decomposition1, namely, Previous workers have found the induced reaction to be inhibited by quinol1 and m-cresol2. On the other hand, when a phenol is used as solvent, it is greatly accelerated3.