Organic peroxides

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The general structure of an organic peroxide Peroxy general.svg
The general structure of an organic peroxide

In organic chemistry, organic peroxides are organic compounds containing the peroxide functional group (R−O−O−R′). If the R′ is hydrogen, the compounds are called hydroperoxides, which are discussed in that article. The O−O bond of peroxides easily breaks, producing free radicals of the form RO• (the dot represents an unpaired electron). Thus, organic peroxides are useful as initiators for some types of polymerization, such as the acrylic, unsaturated polyester, and vinyl ester resins used in glass-reinforced plastics. MEKP and benzoyl peroxide are commonly used for this purpose. However, the same property also means that organic peroxides can explosively combust. Organic peroxides, like their inorganic counterparts, are often powerful bleaching agents. [1]

Contents

Types of organic peroxides

Organic peroxides are classified (i) by the presence or absence of a hydroxyl (-OH) terminus and (ii) by the presence of alkyl vs acyl substituents. [2]

One gap in the classes of organic peroxides is diphenyl peroxide. Quantum chemical calculations predict that it undergoes a nearly barrierless reaction akin to the benzidine rearrangement. [3]

Properties

The O−O bond length in peroxides is about 1.45  Å, and the R−O−O angles (R = H, C) are about 110° (water-like). Characteristically, the C−O−O−R (R = H, C) dihedral angles are about 120°. The O−O bond is relatively weak, with a bond dissociation energy of 45–50  kcal/mol (190–210  kJ/mol ), less than half the strengths of C−C, C−H, and C−O bonds. [4] [5]

Biology

The peroxide ascaridole, derived from terpinene. Ascaridol2.png
The peroxide ascaridole, derived from terpinene.

Peroxides play important roles in biology. Hundreds of peroxides and hydroperoxides are known, being derived from fatty acids, steroids, and terpenes. [6] The prostaglandins are biosynthesized by initial formation of a bicyclic peroxide ("endoperoxide") derived from arachidonic acid. [7]

Many aspects of biodegradation or aging are attributed to the formation and decay of peroxides formed from oxygen in air. Countering these effects, an array of biological and artificial antioxidants destroy peroxides.

In fireflies, oxidation of luciferins, which is catalyzed by luciferases, yields a peroxy compound 1,2-dioxetane. The dioxetane is unstable and decays spontaneously to carbon dioxide and excited ketones, which release excess energy by emitting light (bioluminescence). [8]

Loss of CO2 of a dioxetane, giving rise to an excited ketone, which relaxes by emitting light. Luciferin principle.png
Loss of CO2 of a dioxetane, giving rise to an excited ketone, which relaxes by emitting light.

Industrial uses

In polymer chemistry

Many peroxides are used as a radical initiators, e.g., to enable polymerization of acrylates. Industrial resins based on acrylic and/or methacrylic acid esters are invariably produced by radical polymerization with organic peroxides at elevated temperatures. [9] The polymerization rate is adjusted by suitable choice of temperature and type of peroxide. [10]

Methyl ethyl ketone peroxide, benzoyl peroxide and to a smaller degree acetone peroxide are used as initiators for radical polymerization of some thermosets, e.g. unsaturated polyester and vinyl ester resins, often encountered when making fiberglass or carbon fiber composites (CFRP), with examples including boats, RV units, bath tubs, pools, sporting equipment, wind turbine blades, and a variety of industrial applications.

Benzoyl peroxide, peroxyesters/peroxyketals, and alkylperoxy monocarbonates are used in production of polystyrene, expanded polystyrene, and High Impact Polystyrene, and benzoyl peroxide is utilized for many acrylate based adhesive applications.

Thermoplastic production techniques for many industrial polymerization applications include processes which are carried out in bulk, solution, or suspension type batches. Relevant polymers include: polyvinyl chloride (PVC), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), Polystyrene, and Polycarbonates.

Bleaching and disinfecting agents

Benzoyl peroxide and hydrogen peroxide are used as bleaching and "maturing" agents for treating flour to make its grain release gluten more easily; the alternative is letting the flour slowly oxidize by air, which is too slow for the industrialized era. Benzoyl peroxide is an effective topical medication for treating most forms of acne.

Preparation

From hydrogen peroxide

Dialkyl peroxides, e.g., dicumyl peroxide, are synthesized by addition of hydrogen peroxide to alkenes or by O-alkylation of hydroperoxides.

Diacyl peroxides are typically prepared by treating hydrogen peroxide with acid chlorides or acid anhydrides in the presence of base: [1]

H2O2 + 2 RCOCl → (RCO2)2 + 2 HCl
H2O2 + (RCO)2O → (RCO2)2 + H2O

The reaction competes with hydrolysis of the acylating agent but the hydroperoxide anion is a superior nucleophile relative to hydroxide. Unsymmetrical diacyl peroxides can be produced by treating acyl chlorides with the peroxy acid.

Peresters, an example being tert-Butyl peroxybenzoate, are produced by treating acid anhydrides or acid chlorides with hydroperoxides.

From O2

Cyclic peroxides can be obtained by cycloaddition of singlet oxygen (generated by UV radiation) to dienes. An important example is rubrene. Six-membered cyclic peroxides are called endo peroxides. [11] The four-membered dioxetanes can be obtained by 2+2 cycloaddition of oxygen to alkenes. [12] [13]

The hazards associated with storage of ethers in air is attributed to the formation of hydroperoxides via the direct albeit slow reaction of triplet oxygen with C-H bonds.

Reactions

Homolysis

Organic peroxides are widely used to initiate polymerization of olefins, e.g. the formation of polyethylene. A key step is homolysis:

ROOR ⇌ 2 RO.

The tendency to homolyze is also exploited to modify polymers by grafting or visbreaking, or cross-link polymers to create a thermoset. When used for these purposes, the peroxide is highly diluted, so the heat generated by the exothermic decomposition is safely absorbed by the surrounding medium (e.g. polymer compound or emulsion).

Self-oxidation

Especially when in concentrated form, organic peroxides can decompose by self-oxidation, since organic peroxides contain both an oxidizer (the O-O bond) and fuel (C-H and C-C bonds). A "self-accelerating decomposition" occurs when the rate of peroxide decomposition generates heat at a faster rate than it can be dissipated to the environment. Temperature is the main factor in the rate of decomposition. The lowest temperature at which a packaged organic peroxide will undergo a self-accelerating decomposition within a week is defined as the self-accelerating decomposition temperature (SADT). A large fire at the Arkema Chemical Plant in Crosby, Texas (USA) in 2017 was caused by the decomposition of various organic peroxides following power failure and subsequent loss of cooling systems. [14] This occurred due to extreme flooding from Hurricane Harvey, which destroyed main and back-up power generators at the site. [14]

Cumene process

Hydroperoxides are intermediates or reagents in major commercial processes. In the cumene process, acetone and phenol are produced by decomposition of cumene hydroperoxide (Me = methyl):

C6H5CMe2(O2H) → C6H5OH + O=CMe2

Reduction

Organoperoxides can be reduced to alcohols with lithium aluminium hydride, as described in this idealized equation:

4 ROOH + LiAlH4 → LiAlO2 + 2 H2O + 4 ROH

The phosphite esters and tertiary phosphines also effect reduction:

ROOH + PR3 → P(OR)3 + ROH

Cleavage to ketones and alcohols occurs in the base-catalyzed Kornblum–DeLaMare rearrangement, which involves the breaking of bonds within peroxides to form these products.

Some peroxides are drugs, whose action is based on the formation of radicals at desired locations in the organism. For example, artemisinin and its derivatives, such as artesunate, possess the most rapid action of all current drugs against falciparum malaria. [15] Artesunate is also efficient in reducing egg production in Schistosoma haematobium infection. [16]

Organic synthesis

tert-Butyl hydroperoxide is used for epoxidation and hydroxylation reagents in conjunction with metal catalysts. [17]

Analysis of peroxides

Iodine-starch test. Note the blackening (left) of initially yellowish (right) starch. Jodprobe.jpg
Iodine-starch test. Note the blackening (left) of initially yellowish (right) starch.

Several analytical methods are used for qualitative and quantitative determination of peroxides. [18] A simple qualitative detection of peroxides is carried out with the iodine-starch reaction. [19] Here peroxides, hydroperoxides or peracids oxidize the added potassium iodide into iodine, which reacts with starch producing a deep-blue color. Commercial paper indicators using this reaction are available. This method is also suitable for quantitative evaluation, but it can not distinguish between different types of peroxide compounds. Discoloration of various indigo dyes in presence of peroxides is used instead for this purpose. [20] For example, the loss of blue color in leuco-methylene blue is selective for hydrogen peroxide. [21]

Quantitative analysis of hydroperoxides can be performed using potentiometric titration with lithium aluminium hydride. [22] Another way to evaluate the content of peracids and peroxides is the volumetric titration with alkoxides such as sodium ethoxide. [23]

Active oxygen in peroxides

Each peroxy group is considered to contain one active oxygen atom. The concept of active oxygen content is useful for comparing the relative concentration of peroxy groups in formulations, which is related to the energy content. In general, energy content increases with active oxygen content, and thus the higher the molecular weight of the organic groups, the lower the energy content and, usually, the lower the hazard.

The term active oxygen is used to specify the amount of peroxide present in any organic peroxide formulation. One of the oxygen atoms in each peroxide group is considered "active". The theoretical amount of active oxygen can be described by the following equation: [24]

where p is the number of peroxide groups in the molecule, and m is the molecular mass of the pure peroxide.

Organic peroxides are often sold as formulations that include one or more phlegmatizing agents. That is, for safety sake or performance benefits the properties of an organic peroxide formulation are commonly modified by the use of additives to phlegmatize (desensitize), stabilize, or otherwise enhance the organic peroxide for commercial use. Commercial formulations occasionally consist of mixtures of organic peroxides, which may or may not be phlegmatized.

Safety

The GHS transport pictogram for organic peroxides. UN transport pictogram - 5.2 (white).svg
The GHS transport pictogram for organic peroxides.

Peroxides are also strong oxidizers and easily react with skin, cotton and wood pulp. [25] For safety reasons, peroxidic compounds are stored in a cool, opaque container, as heating and illumination accelerate their chemical reactions. Small amounts of peroxides, which emerge from storage or reaction vessels are neutralized using reducing agents such as iron(II) sulfate. Safety measures in industrial plants producing large amounts of peroxides include the following:

1) The equipment is located within reinforced concrete structures with foil windows, which would relieve pressure and not shatter in case of explosion.

2) The products are bottled in small containers and are moved to a cold place promptly after the synthesis.

3) The containers are made of non-reactive materials such as stainless steel, some aluminium alloys or dark glass. [26]

For safe handling of concentrated organic peroxides, an important parameter is temperature of the sample, which should be maintained below the self accelerating decomposition temperature of the compound. [27]

The shipping of organic peroxides is restricted. The US Department of Transportation lists organic peroxide shipping restrictions and forbidden materials in 49 CFR 172.101 Hazardous Materials Table based on the concentration and physical state of the material:

Chemical name CAS Number Prohibitions
Acetyl acetone peroxide 37187-22-7> 9% by mass active oxygen
Acetyl benzoyl peroxide 644-31-5solid, or > 40% in solution
Ascaridole 512-85-6(organic peroxide)
tert-Butyl hydroperoxide 75-91-2> 90% in solution (aqueous)
Di-(1-naphthoyl)peroxide 29903-04-6
Diacetyl peroxide 110-22-5solid, or > 25% in solution
Ethyl hydroperoxide 3031-74-1
Methyl ethyl ketone peroxide 1338-23-4> 9% by mass active oxygen in solution
Methyl isobutyl ketone peroxide 37206-20-5> 9% by mass active oxygen in solution

See also

Related Research Articles

<span class="mw-page-title-main">Ether</span> Organic compounds made of alkyl/aryl groups bound to oxygen (R–O–R)

In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two organyl groups. They have the general formula R−O−R′, where R and R′ represent 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">Epoxide</span> Organic compounds with a carbon-carbon-oxygen ring

In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile.

Methyl ethyl ketone peroxide (MEKP) is an organic peroxide with the formula [(CH3)(C2H5)C(O2H)]2O2. MEKP is a colorless oily liquid. It is widely used in vulcanization (crosslinking) of polymers.

<span class="mw-page-title-main">Benzoyl peroxide</span> Chemical compound with uses in industry and acne treatment

Benzoyl peroxide is a chemical compound (specifically, an organic peroxide) with structural formula (C6H5−C(=O)O−)2, often abbreviated as (BzO)2. In terms of its structure, the molecule can be described as two benzoyl (C6H5−C(=O)−, Bz) groups connected by a peroxide (−O−O−). It is a white granular solid with a faint odour of benzaldehyde, poorly soluble in water but soluble in acetone, ethanol, and many other organic solvents. Benzoyl peroxide is an oxidizer, which is principally used as in the production of polymers.

<span class="mw-page-title-main">Peroxy acid</span> Organic acid having a peroxide bond

A peroxy acid is an acid which contains an acidic –OOH group. The two main classes are those derived from conventional mineral acids, especially sulfuric acid, and the peroxy derivatives of organic carboxylic acids. They are generally strong oxidizers.

The Baeyer–Villiger oxidation is an organic reaction that forms an ester from a ketone or a lactone from a cyclic ketone, using peroxyacids or peroxides as the oxidant. The reaction is named after Adolf von Baeyer and Victor Villiger who first reported the reaction in 1899.

Autoxidation refers to oxidations brought about by reactions with oxygen at normal temperatures, without the intervention of flame or electric spark. The term is usually used to describe the gradual degradation of organic compounds in air at ambient temperatures. Many common phenomena can be attributed to autoxidation, such as food going rancid, the 'drying' of varnishes and paints, and the perishing of rubber. It is also an important concept in both industrial chemistry and biology. Autoxidation is therefore a fairly broad term and can encompass examples of photooxygenation and catalytic oxidation.

<span class="mw-page-title-main">Hydroperoxide</span> Class of chemical compounds

Hydroperoxides or peroxols are compounds of the form ROOH, where R stands for any group, typically organic, which contain the hydroperoxy functional group. Hydroperoxide also refers to the hydroperoxide anion and its salts, and the neutral hydroperoxyl radical (•OOH) consist of an unbond hydroperoxy group. When R is organic, the compounds are called organic hydroperoxides. Such compounds are a subset of organic peroxides, which have the formula ROOR. Organic hydroperoxides can either intentionally or unintentionally initiate explosive polymerisation in materials with unsaturated chemical bonds.

<span class="mw-page-title-main">Dakin oxidation</span> Organic redox reaction that converts hydroxyphenyl aldehydes or ketones into benzenediols

The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H2O2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H2O2 is reduced.

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

Lithium peroxide is the inorganic compound with the formula Li2O2. Lithium peroxide appears as white powder, and unlike most other alkali metal peroxides, it is nonhygroscopic. Because of its high oxygen:mass and oxygen:volume ratios, the solid has been used to remove CO2 and release high-purity O2 from the atmosphere in spacecraft.

<span class="mw-page-title-main">Photoinitiator</span> Molecule which creates reactive species when exposed to radiation

In chemistry, a photoinitiator is a molecule that creates reactive species when exposed to radiation. Synthetic photoinitiators are key components in photopolymers.

Polymer stabilizers are chemical additives which may be added to polymeric materials, such as plastics and rubbers, to inhibit or retard their degradation. Common polymer degradation processes include oxidation, UV-damage, thermal degradation, ozonolysis, combinations thereof such as photo-oxidation, as well as reactions with catalyst residues, dyes, or impurities. All of these degrade the polymer at a chemical level, via chain scission, uncontrolled recombination and cross-linking, which adversely affects many key properties such as strength, malleability, appearance and colour.

<span class="mw-page-title-main">Photo-oxidation of polymers</span>

In polymer chemistry photo-oxidation is the degradation of a polymer surface due to the combined action of light and oxygen. It is the most significant factor in the weathering of plastics. Photo-oxidation causes the polymer chains to break, resulting in the material becoming increasingly brittle. This leads to mechanical failure and, at an advanced stage, the formation of microplastics. In textiles the process is called phototendering.

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

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.

<span class="mw-page-title-main">Cumene hydroperoxide</span> Aromatic organic chemical compound

Cumene hydroperoxide is the organic compound with the formula C6H5C(CH3)2OOH. An oily liquid, it is classified as an organic hydroperoxide. Products of decomposition of cumene hydroperoxide are methylstyrene, acetophenone, and 2-Phenyl-2-propanol.

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

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.

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

Trifluoroperacetic acid is an organofluorine compound, the peroxy acid analog of trifluoroacetic acid, with the condensed structural formula CF
3COOOH. 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.

<span class="mw-page-title-main">Metal peroxide</span>

Metal peroxides are metal-containing compounds with ionically- or covalently-bonded peroxide (O2−
2) groups. This large family of compounds can be divided into ionic and covalent peroxide. The first class mostly contains the peroxides of the alkali and alkaline earth metals whereas the covalent peroxides are represented by such compounds as hydrogen peroxide and peroxymonosulfuric acid (H2SO5). In contrast to the purely ionic character of alkali metal peroxides, peroxides of transition metals have a more covalent character.

<span class="mw-page-title-main">1,2-Dioxolane</span> Chemical compound

1,2-Dioxolane is a chemical compound with formula C3H6O2, consisting of a ring of three carbon atoms and two oxygen atoms in adjacent positions. Its condensed structural formula is [–(CH
2)3–O–O–].

In chemistry, the Halcon process refers to technology for the production of propylene oxide by oxidation of propylene with tert-butyl hydroperoxide. The reaction requires metal catalysts, which typically contain molybdenum:

References

  1. 1 2 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. ↑ Saul Patai, ed. (1983). PATAI'S Chemistry of Functional Groups: Peroxides. Wiley. ISBN   9780470771730.
  3. ↑ "Henry Rzepa's Blog: Why diphenyl peroxide does not exist".
  4. ↑ Bach, Robert D.; Ayala, Philippe Y.; Schlegel, H. B. (1996). "A Reassessment of the Bond Dissociation Energies of Peroxides. An ab Initio Study". J. Am. Chem. Soc. 118 (50): 12758–12765. doi:10.1021/ja961838i.
  5. ↑ Otto Exner (1983). "Stereochemical and conformational aspects of peroxy compounds". In Saul Patai (ed.). PATAI'S Chemistry of Functional Groups. Wiley. pp. 85–96. doi:10.1002/9780470771730.ch2. ISBN   9780470771730.
  6. ↑ D. A. Casteel (1992). "Peroxy Natural Products". Natural Product Reports. 9 (4): 289–312. doi:10.1039/np9920900289. PMID   1522977.
  7. ↑ Rouzer, Carol A.; Marnett, Lawrence J. (2003). "Mechanism of Free Radical Oxygenation of Polyunsaturated Fatty Acids by Cyclooxygenases". Chemical Reviews. 103 (6): 2239–2304. doi:10.1021/cr000068x. PMID   12797830.
  8. ↑ Aldo Roda Chemiluminescence and Bioluminescence: Past, Present and Future, p. 57, Royal Society of Chemistry, 2010, ISBN   1-84755-812-7
  9. ↑ Thomas Brock, Michael Groteklaes, Peter Mischke Lehrbuch der Lacktechnologie, Vincentz Network GmbH & Co KG, 2000, ISBN   3-87870-569-7 p. 67
  10. ↑ Organische Peroxide für die Polymerisation Archived 2016-06-29 at the Wayback Machine . pergan.com (in German)
  11. ↑ Aubry, Jean-Marie; Pierlot, Christel; Rigaudy, Jean; Schmidt, Reinhard (2003). "Reversible Binding of Oxygen to Aromatic Compounds". Accounts of Chemical Research. 36 (9): 668–675. doi:10.1021/ar010086g. PMID   12974650.
  12. ↑ Heinz G. O. Becker Organikum, Wiley-VCH, 2001, ISBN   3-527-29985-8, p. 323
  13. ↑ Criegee, Rudolf; Müller, Gerhard (1956). "1.2-Dioxan". Chemische Berichte. 89 (2): 238. doi:10.1002/cber.19560890209.
  14. 1 2 USCSB. "Caught in the Storm: Extreme Weather Hazards". Youtube. USCSB. Retrieved 29 June 2023.
  15. ↑ White NJ (1997). "Assessment of the pharmacodynamic properties of antimalarial drugs in vivo". Antimicrob. Agents Chemother. 41 (7): 1413–22. doi:10.1128/AAC.41.7.1413. PMC   163932 . PMID   9210658.
  16. ↑ Boulangier D, Dieng Y, Cisse B, et al. (2007). "Antischistosomal efficacy of artesunate combination therapies administered as curative treatments for malaria attacks". Trans R Soc Trop Med Hyg. 101 (2): 113–16. doi:10.1016/j.trstmh.2006.03.003. PMID   16765398. S2CID   1675813.
  17. ↑ Zhu, Nengbo; Yao, Huijie; Zhang, Xiyu; Bao, Hongli (2024). "Metal-catalyzed asymmetric reactions enabled by organic peroxides". Chemical Society Reviews. 53 (5): 2326–2349. doi:10.1039/D3CS00735A. PMID   38259195.
  18. ↑ Légrádi, L.; Légrádi, J. (1970). "Detection of peroxides, hydroperoxides and peracids". Microchimica Acta. 58: 119–122. doi:10.1007/BF01218105. S2CID   101877371.
  19. ↑ Lea, C. H. (1931). "The Effect of Light on the Oxidation of Fats". Proceedings of the Royal Society B: Biological Sciences. 108 (756): 175–189. Bibcode:1931RSPSB.108..175L. doi: 10.1098/rspb.1931.0030 .
  20. ↑ Veibel, S. Analytik organischer Verbindungen, Akademie-Verlag, Berlin, 1960, p. 262
  21. ↑ Eiss, M. I.; Giesecke, Paul (1959). "Colorimetric Determination of Organic Peroxides". Analytical Chemistry. 31 (9): 1558. doi:10.1021/ac60153a038.
  22. ↑ Higuchi, T.; Zuck, Donald Anton (1951). "Behaviors of Several Compounds as Indicators in Lithium Aluminum Hydride Titration of Functional Groups". Journal of the American Chemical Society. 73 (6): 2676. doi:10.1021/ja01150a073.
  23. ↑ Martin, A. J. (1957). "Potentiometric titration of hydroperoxide and peracid in Anhydrous Ethylenediamine". Analytical Chemistry. 29: 79–81. doi:10.1021/ac60121a022.
  24. ↑ "ASTM E298, Standard Test Methods for Assay of Organic Peroxides". ASTM. 2010.
  25. ↑ Heinz G. O. Becker Organikum, Wiley-VCH, 2001, ISBN   3-527-29985-8 pp. 741–762
  26. ↑ Ozonelab Peroxide compatibility
  27. ↑ "Product Stewardship". American Chemistry Council. 2021-01-17. Retrieved 2022-01-03.
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