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Peroxide Forming Chemicals CONTENTS Introduction Neutralisation of peroxides Tables Table 1: Organic Functional Groups Prone to Peroxide Formation Table 2: Inorganic Substances Prone to Peroxide Formation Table 3: Common Peroxide Forming Chemicals and Recommendation For Their Testing and Disposal References Introduction There are many organic functional groups and inorganic substances that are susceptible to peroxide formation. These are shown in Table 1 and Table 2, respectively. Examples of specific chemicals that undergo peroxide formation are listed in Table 3, along with recommendations for the testing of peroxides in, and / or the disposal of, the peroxide forming chemicals which are listed. Tables No. Functional Group Description - hydrogen atoms 1 | H-C-O-R | \ | C=C-C-H / | Alkenes with allylic hydrogen atoms 2 \ | C=C-X / Chloro- and fluoro- alkenes 3 \ C=CH2 / Vinyl halides, esters and ethers 4 \ | | / C=C-C=C / \ Dienes 5 \ C=C(H)-C≡C-H / - hydrogen atoms 6 | H-C-C≡C-H | - hydrogen atoms 7 8 | H-C-Ar | Work Environment Group HR Division Alkyl aromatics hydrogen atoms containing tertiary 1 Version 1: June 2011 9 | H-C-R | Alkanes and cycloalkanes tertiary hydrogen atoms containing \ C=C-C(O)OR / Acrylactes and methacrylates 10 | H-C-OH | Secondary alcohols 11 12 \ H-C-C(O)/ | H-C=O Aldehydes 13 14 \ | H-C-N(H)-C=O / Amides, ureas and lactams that have an ahydrogen atom on a carbon attached to a nitrogen - hydrogen atoms Where: R is an alkyl group X is a chlorine or fluorine atom; and Ar is an aromatic group. Table 1: Organic Functional Groups That Are Prone To Form Peroxides (Listed in decreasing order of approximate likelihood of peroxide formation) Type Examples Alkali metals Potassium, Rubidium, Caesium Metal amides Sodium amide, Potasium amide Organometallics n-Butyllithium, Phenyllithium, Phenylsodium Metal alkoxides Aluminium n-butoxide, Iron (III) ethoxide Table 2: Inorganic Substances That Are Prone To Form Peroxides Work Environment Group HR Division 2 Version 1: June 2011 Severe Peroxide Hazard a Discard within 3 months Diisopropyl ether (isopropyl ether) Divinylacetylene (DVA) Potassium metal Potassium amide Sodium amide (sodamide) Vinylidene chloride (1,1-dichloroethylene) [a] [b] [c] [d] Peroxide Hazard On Concentration b Discard or test for peroxides after 6 months Acetaldehyde diethyl acetal Cumene Cyclohexene Cyclopentene Decalin Diacetylene (1,3-butadiyne) Dicyclopentadiene Diethyl ether Diethylene glycol dimethyl ether Dioxane Ethylene glycol dimethyl ether Ethylene glycol ether acetates Ethylene glycol monoethers Furan Methylacetylene Methylcyclopentane Methyl isobutyl ketone Tetrahydrofuran (THF) Tettralin Vinyl ethers Potential For Rapid Polymerisation c Discard or test for peroxides after 6 months Chloroprene (2-chloro-1,3butadiene) d Styrene Vinyl acetate Vinyl pyridine Discard after 12 months Butadiene d Tetrafluoroethylene (TFE) d Vinylacetylene (MVA) d Vinyl chloride On storage with exposure to air Do not distil or evaporate without first testing for the presence of peroxides Due to Internally Formed Peroxides When stored in liquid phase without an inhibitor, these should be considered to pose a severe peroxide hazard, and be discarded within 3 months of exposure to air. Table 3: Common Peroxide Forming Chemicals Removal of peroxides If a precipitate or crystals are present in a peroxide-forming chemical do not open the lid. Secure and label the area around the chemical so that it is protected from movement and can’t be disturbed. The chemical should be disposed of in a safe manner by a specialised waste contractor, or the local budget unit’s Hazardous Waste Safety Officer or the Work Environment Group contacted for advice on the treatment of the chemical. Peroxides may be removed using one of the two methods below: Method 1 Pass the solvent through a short column of activated alumina. (A suggested amount is 100g of alumina per 100mL of solvent). Retest the solvent to ensure that peroxides have been removed. Some peroxide may be retained on the column, which should then be disposed of as a flammable material. Solvents purified in this way should be used directly and not stored further as any peroxide-forming inhibitor will probably have been removed (see Standard Laboratory Practises Document for testing). Method 2 Work Environment Group HR Division 3 Version 1: June 2011 Shake gently the solvent with a freshly prepared solution of iron (II) sulphate (60g iron (II) sulphate, 6mL concentrated sulphuric acid and 110mL water per litre of ether). Repeat until peroxides are no longer detected after testing (see Standard Laboratory Practises Document for testing). Shake very gently for the first extraction. Be careful of rise in temperature and build up of pressure. References 1. National Research Council, Prudent Practices in the Laboratory: Handling and Disposal of Chemicals, National Academy Press, Washington D.C. (1995). 2. Bretherick, L., Bretherick’s Handbook of Reactive Chemical Hazards, 4th Edition, London: Butterworth. (1990). Work Environment Group HR Division 4 Version 1: June 2011