tert-Butyl hydroperoxide

Description

tert-Butyl hydroperoxide (TBHP) is an organic peroxide widely used in a variety of oxidation processes.

Chemical properties

tert-Butyl hydroperoxide (TBHP) is a water-white liquid commonly commercially available as a 70% solution in water; 80% solutions are also available. It is used to initiate polymerization reactions and in organic syntheses to introduce peroxy groups into the molecule. TBHP vapor can burn in the absence of air and may be flammable at either elevated temperature or at reduced pressure. Fine mist/spray may be combustible at temperatures below the normal flash point. When evaporated, the residual liquid will concentrate TBHP content and may reach an explosive concentration (＞90%). Closed containers may generate internal pressure through the degradation of TBHP to oxygen . TBHP is a highly reactive product. The three types of significant physical hazards are flammability, thermal, and decomposition due to contamination. To minimize these hazards, avoid exposure to heat, fire, or any condition that will concentrate the liquid material. Store away from heat, sparks, open flames, foreign contaminants, combustibles, and reducing agents. Inspect containers frequently to identify bulges or leaks (7a, 125).

The Uses of tert-Butyl hydroperoxide

tert-Butyl hydroperoxide is used as an initiator for radical polymerization and in various oxidation process such as sharpless epoxidation. It is involved in osmium catalyzed vicinal hydroxylation of olefins under alkaline conditions. Furthermore, it is used in catalytic asymmetric oxidation of sulfides to sulfoxides using binaphthol as a chiral auxiliary and in the oxidation of dibenzothiophenes. It plays an important role for the introduction of peroxy groups in organic synthesis.

The Uses of tert-Butyl hydroperoxide

TBHP is an intermediate in the production of propylene oxide and t-butyl alcohol from isobutane and propylene. It is primarily used as an initiator and finishing catalyst in the solution and emulsion polymerization methods for polystyrene and polyacrylates. Other uses are for the polymerization of vinyl chloride and vinyl acetate and as an oxidation and sulfonation catalyst in bleaching and deodorizing operations. It is a strong oxidant and reacts violently with combustible and reducing materials, and metallic and sulfur compounds.

Definition

ChEBI: Tert-butyl hydroperoxide is an alkyl hydroperoxide in which the alkyl group is tert-butyl. It is widely used in a variety of oxidation processes. It has a role as an antibacterial agent and an oxidising agent.

Production Methods

TBHP is produced by the liquid-phase reaction of isobutane and molecular oxygen or by mixing equimolar amounts of t-butyl alcohol and 30–50% hydrogen peroxide. TBHP can also be prepared from t-butyl alcohol and 30% hydrogen peroxide in the presence of sulfuric acid or by oxidation of tert-butylmagnesium chloride. The manufacturing process of TBHP is in a closed system.

General Description

Watery odorless colorless liquid. Floats and mixes slowly with water.

Air & Water Reactions

Water soluble.

Reactivity Profile

Most alkyl monohydroperoxides are liquid. The explosivity of the lower members (e.g., methyl hydroperoxide, or possibly, traces of the dialkyl peroxides) decreasing with increasing chain length and branching [Bretherick 2nd ed. 1979 p. 10]. Though relatively stable, explosions have been caused by distillation to dryness [Milas, JACS 1946, 68, 205] or attempted distillation at atmospheric pressure [Castrantas 1965 p. 15].

Hazard

Moderate fire risk. Oxidizer.

Health Hazard

tert-Butyl hydroperoxide is a strong irritant.Floyd and Stockinger (1958) observed thatdirect cutaneous application in rats did notcause immediate discomfort, but the delayedaction was severe. The symptoms were erythemaand edema within 2–3 days. Exposureto 500 mg in 24 hours produced asevere effect on rabbit skin, while a rinse of150 mg/min was severe to eyes.
It is moderately toxic; the effects aresomewhat similar to those of MEK peroxide.Symptoms from oral administration in ratswere weakness, shivering, and prostration.
LD₅₀ value, intraperitoneal (rats): 87 mg/kg
LD₅₀ value, oral (rats): 406 mg/kg.

Flammability and Explosibility

tert-Butyl hydroperoxide is a flammable liquid and a highly reactive oxidizing agent. Pure TBHP is shock sensitive and may explode on heating. Carbon dioxide or dry chemical extinguishers should be used for fires involving tert-butyl hydroperoxide.

Mechanism of action

The general mechanism of transition metal-catalyzed oxidative Mannich reactions of N, N-dialkyl anilines with tert-butyl hydroperoxide (TBHP) as the oxidant consists of a rate-determining single electron transfer (SET) that is uniform from 4-methoxy- to 4-cyano-N, N-dimethylanilines. The tert-butylperoxy radical is the major oxidant in the rate-determining SET step that is followed by competing backward SET and irreversible heterolytic cleavage of the carbon–hydrogen bond at the α-position to nitrogen. A second SET completes the conversion of N, N-dimethylaniline to an iminium ion that is subsequently trapped by the nucleophilic solvent or the oxidant prior to the formation of the Mannich adduct[1].
Tert-butyl hydroperoxide could induce oxidative stress in liver mitochondria at low concentrations. The damaging effect of low concentrations of tBHP in the course of pyruvate oxidation in isolated liver mitochondria is caused by the opening of the nonspecific Ca²⁺-dependent cyclosporin A-sensitive pore in the inner mitochondrial membrane[2].

Safety Profile

Moderately toxic by ingestion and inhalation. A severe skin and eye irritant. Mutation data reported. At highest dosage levels, symptoms noted were severe depression, incoordmation, and cyanosis. Death was due to respiratory arrest. Very dangerous fire hazard when exposed to heat or flame, or by spontaneous chemical reaction such as with reducing materials. Moderately explosive; may explode during distillation. Violent reaction with traces of acid. Concentrated solutions may ignite spontaneously on contact with molecular sieve. Mixtures with transition metal salts may react vigorously and release oxygen. Forms an unstable solution with 1,2-dichloroethane. To fight fire, use alcohol foam, CO2, dry chemical. When heated to decomposition it emits acrid smoke and fumes. See also PEROXIDES, ORGANIC.

Carcinogenicity

A study performed to evaluate the carcinogenicity of TBHP found it was not carcinogenic when applied to the skin of mice at 16.6% of the peroxide 6 times a week for 45 weeks. However, if its application was preceded by 0.05 mg of 4-nitroquinoline-1-oxide as a 0.25% solution in benzene applied 20 times over 7 weeks followed by TBHP (16.6% in benzene), then malignant skin tumors appeared between days 390 and 405 of the experiment . This supports the theory that peroxides are not complete carcinogens, but may act as promoters . The effects of TBHP on promotable and nonpromotable mouse epidermal cell culture lines were reported by Muehlematter et al. .

storage

tert-butyl hydroperoxide should be stored in the dark at room temperature (do not refrigerate) separately from oxidizable compounds, flammable substances, and acids. Reactions involving this substance should be carried out behind a safety shield.

Toxicity evaluation

TBHP accelerates oxidation of glutathione and decreases the metabolism of sodium hexobarbital in rat livers and is a strong oxidation agent.

Incompatibilities

tert-Butyl hydroperoxide and concentrated aqueous solutions of TBHP react violently with traces of acid and the salts of certain metals, including, in particular, manganese, iron, and cobalt. Mixing anhydrous tert-butyl hydroperoxide with organic and readily oxidized substances can cause ignition and explosion. TBHP can initiate polymerization of certain olefins.

Waste Disposal

Excess tert-butyl hydroperoxide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

References

[1] Maxim O, et al. Mechanistic Investigation of Oxidative Mannich Reaction with tert-Butyl Hydroperoxide. The Role of Transition Metal Salt. Journal of the American Chemical Society, 2013; 135: 1549–1557.
[2] Fedotcheva N, et al. Mechanism of induction of oxidative stress in liver mitochondria by low concentrations of tert-butyl hydroperoxide. Biochemistry (Moscow), 2013; 78: 75–79.