Tert-Butyl peroxybenzoate

Last updated
tert-Butyl peroxybenzoate
Tert-Butylperoxybenzoat Strukturformel.svg
Names
Preferred IUPAC name
tert-Butyl benzenecarboperoxoate
Other names
tert-Butyl perbenzoate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.009.440 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
UNII
  • InChI=1S/C11H14O3/c1-11(2,3)14-13-10(12)9-7-5-4-6-8-9/h4-8H,1-3H3
    Key: GJBRNHKUVLOCEB-UHFFFAOYSA-N
  • CC(C)(C)OOC(=O)c1ccccc1
Properties
C11H14O3
Molar mass 194.230 g·mol−1
Density 1.034 g/cm3
Melting point 8-9 °C
Boiling point 112 °C (decomposes)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

tert-Butyl peroxybenzoate (TBPB) an organic compound with the formula C6H5CO3CMe3 (Me = CH3). It is the most widely produced perester; it is an ester of peroxybenzoic acid (C6H5CO3H). It is often used as a radical initiator in polymerization reactions, such as the production of LDPE from ethylene, and for crosslinking, such as for unsaturated polyester resins. [1]

Contents

Properties

TBPB, which is pale yellow, is exclusively encountered as a solution in solvents such as ethanol or phthalate. [2]

As peroxo compound, TBPB contains about 8.16 wt% of active oxygen and has a self accelerating decomposition temperature (SADT) of about 60 °C. The SADT is the lowest temperature at which self-accelerating decomposition in the transport packaging can occur within a week, and which should not be exceeded while storage or transportation. [3] TBPB should therefore be stored between minimum 10 °C (below solidification) and maximum 50 °C. Dilution with a high-boiling solvent increases the SADT. The half-life of TBPB, in which 50% of the peroxy ester is decomposed, is 10 hours at 104 °C, one hour at 124 °C and one minute at 165 °C. Amines, metal ions, strong acids and bases, as well as strong reducing and oxidizing agents accelerate the decomposition of TBPB even in low concentrations. [3] However, TBPB is one of the safest peresters or organic peroxides in handling. [4] The main decomposition products of tert-butyl peroxybenzoate are carbon dioxide, acetone, methane, tert-butanol, benzoic acid and benzene. [5]

Production

A standard procedure for the preparation of peresters is the acylation of tert-butyl hydroperoxide with benzoyl chloride. [6] In the reaction a large excess of tert-butyl hydroperoxide is used and the hydrogen chloride formed is removed in vacuo whereby a virtually quantitative yield is obtained.

Synthesis of tert-butylperoxybenzoate Tert-Butylperoxybenzoat Synthese.svg
Synthesis of tert-butylperoxybenzoate

Applications

In polymer chemistry

Primarily, TBPB is used as a radical initiator, either in the polymerization of e.g. ethylene (to LDPE), vinyl chloride, styrene or acrylic esters or as so-called unsaturated polyester resins (UP resins). [2] The quantity used for the curing of UP resins is about 1-2%. [2]

A disadvantage, particularly in the production of polymers for applications in the food or cosmetics sector, is the possible formation of benzene as a decomposition product which can diffuse out of the polymer (for example, an LDPE packaging film).

In organic chemistry

The protecting group 2-trimethylsilylethanesulfonyl chloride (SES-Cl) for primary and secondary amino groups is accessible by the reaction of vinyltrimethylsilane with sodium hydrogensulfite and TBPB to the sodium salt of trimethylsilylethanesulfonic acid and the subsequent reaction with thionyl chloride to the corresponding sulfonyl chloride. [4]

Synthethis of the protecting group SES-Cl Synthese von SES-Cl.svg
Synthethis of the protecting group SES-Cl

TBPB can be used to introduce a benzoyloxy group in the allyl position of unsaturated hydrocarbons. [7]

Synthesis of 3-benzoyloxycyclohexene 3-Benzoyloxycyclohexen-Synthese 2.svg
Synthesis of 3-benzoyloxycyclohexene

From cyclohexene, 3-benzoyloxycyclohexene is formed with TBPB in the presence of catalytic amounts of copper(I)bromide in 71 to 80% yield.

This allylic oxidation of alkenes, also known as Kharasch-Sosnovsky oxidation, generates racemic allylic benzoates in the presence of catalytic amounts of copper(I)bromide. [8]

Kharasch-Sosnovsky reaction Kharasch-Sosnovsky-Reaktion Prinzip.svg
Kharasch-Sosnovsky reaction

A modification of the reaction utilizes copper(II) trifluoromethanesulfonate as a catalyst and DBN or DBU as bases to achieve yields up to 80% in the reaction of acyclic olefins with TBPB to allylic benzoates. [9]

Substituted oxazolines and thiazolines can be oxidized to the corresponding oxazoles and thiazoles in a modified Kharash-Sosnovsky oxidation with TBPB and a mixture of Cu(I) and Cu(II) salts in suitable yields. [10]

Kharasch-Sosnovsky reaction for oxidation of oxazolines and thiazolines Modifizierte Kharasch-Sosnovsky-Reaktion.svg
Kharasch-Sosnovsky reaction for oxidation of oxazolines and thiazolines

The carboalkoxy group at the C-4 position is essential a successful reaction.

Benzene and furans can be alkenylated with olefins in an oxidative coupling under palladium salt catalysis, with TBPB as hydrogen acceptor. [11]

Oxidative coupling of alkenes and aromatics with TBPB Oxidative Kupplung von Alkenen mit TBPB.svg
Oxidative coupling of alkenes and aromatics with TBPB

In the absence of Pd2+ salts, the aromatics are benzoxylated.

Related Research Articles

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In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom bonded to two organyl groups. They have the general formula R−O−R′, where R and R′ represent the organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether". Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.

<span class="mw-page-title-main">Petrochemical</span> Chemical product derived from petroleum

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<span class="mw-page-title-main">Polyethylene</span> Most common thermoplastic polymer

Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.

<span class="mw-page-title-main">Epoxide</span> Organic compounds with a carbon-carbon-oxygen ring

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<span class="mw-page-title-main">Allyl group</span> Chemical group (–CH₂–CH=CH₂)

In organic chemistry, an allyl group is a substituent with the structural formula −CH2−HC=CH2. It consists of a methylene bridge attached to a vinyl group. The name is derived from the scientific name for garlic, Allium sativum. In 1844, Theodor Wertheim isolated an allyl derivative from garlic oil and named it "Schwefelallyl". The term allyl applies to many compounds related to H2C=CH−CH2, some of which are of practical or of everyday importance, for example, allyl chloride.

<span class="mw-page-title-main">Oxazole</span> Chemical compound

Oxazole is the parent compound for a vast class of heterocyclic aromatic organic compounds. These are azoles with an oxygen and a nitrogen separated by one carbon. Oxazoles are aromatic compounds but less so than the thiazoles. Oxazole is a weak base; its conjugate acid has a pKa of 0.8, compared to 7 for imidazole.

<i>tert</i>-Butyl alcohol Chemical compound

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tert-Butyl hydroperoxide (tBuOOH) is the organic compound with the formula (CH3)3COOH. It is one of the most widely used hydroperoxides in a variety of oxidation processes, like the Halcon process. It is normally supplied as a 69–70% aqueous solution. Compared to hydrogen peroxide and organic peracids, tert-butyl hydroperoxide is less reactive and more soluble in organic solvents. Overall, it is renowned for the convenient handling properties of its solutions. Its solutions in organic solvents are highly stable.

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Oxazoline is a five-membered heterocyclic organic compound with the formula C3H5NO. It is the parent of a family of compounds called oxazolines, which contain non-hydrogenic substituents on carbon and/or nitrogen. Oxazolines are the unsaturated analogues of oxazolidines, and they are isomeric with isoxazolines, where the N and O are directly bonded. Two isomers of oxazoline are known, depending on the location of the double bond.

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3
COOOH
. It is a strong oxidizing agent for organic oxidation reactions, such as in Baeyer–Villiger oxidations of ketones. It is the most reactive of the organic peroxy acids, allowing it to successfully oxidise relatively unreactive alkenes to epoxides where other peroxy acids are ineffective. It can also oxidise the chalcogens in some functional groups, such as by transforming selenoethers to selones. It is a potentially explosive material and is not commercially available, but it can be quickly prepared as needed. Its use as a laboratory reagent was pioneered and developed by William D. Emmons.

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References

  1. Klenk, Herbert; Götz, Peter H.; Siegmeier, Rainer; Mayr, Wilfried. "Peroxy Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_199.pub2. ISBN   978-3527306732.
  2. 1 2 3 United Initiators, Technisches Datenblatt, TBPB
  3. 1 2 Organic Peroxide Producers Safety Division, SAFETY AND HANDLING OF ORGANIC PEROXIDES The Society of the Plastics Industry, 2012 edition Archived 2016-04-01 at the Wayback Machine
  4. 1 2 "2-Trimethylsilylethanesulfonyl chloride (SES-Cl)". Organic Syntheses . doi:10.15227/orgsyn.075.0161 .
  5. PERGAN GmbH: Organische Peroxide für die Polymerisation
  6. N.A. Milas, D.G. Orphanos, R.J. Klein (1964), "The solvolysis of acid chlorides with t-alkyl hydroperoxides", J. Org. Chem., vol. 29, no. 10, pp. 3099–3100, doi:10.1021/jo01033a525 {{citation}}: CS1 maint: multiple names: authors list (link)
  7. "3-Benzoyloxycyclohexene". Organic Syntheses . doi:10.15227/orgsyn.048.0018 .
  8. M.S. Kharasch, G. Sosnovsky (1958), "The reactions of t-butyl perbenzoate and olefins – a stereospecific reaction", J. Am. Chem. Soc., vol. 80, no. 3, p. 756, doi:10.1021/ja01536a062
  9. G. Sakar, A. DattaGupta, V.K. Singh (1996), "Cu(OTf)2 – DBN/DBU complex as an efficient catalyst for allylic oxidation of olefins with tert-butyl perbenzoate", Tetrahedron Lett., vol. 37, no. 46, pp. 8435–8436, doi:10.1016/0040-4039(96)01911-9 {{citation}}: CS1 maint: multiple names: authors list (link)
  10. A.I. Meyers, F.X. Tavares (1996), "Oxidation of Oxazolines and Thiazolines to Oxazoles and Thiazoles. Application of the Kharasch−Sosnovsky Reaction", J. Org. Chem., vol. 61, no. 23, pp. 8207–8215, doi:10.1021/jo9613491, PMID   11667808
  11. J. Tsuji, H. Nagashima (1984), "Palladium-catalyzed oxidative coupling of aromatic compounds with olefins using t-butyl perbenzoate as a hydrogen accepter", Tetrahedron, vol. 40, no. 14, pp. 2699–2702, doi:10.1016/S0040-4020(01)96888-7