Formation of Explosive Peroxides

The fluorine radical is the most reactive of the halogen radicals—it reacts readily with alkanes (AH° = -31 kcal/mol), and the radical it produces reacts violently with F2 (AH° = —11 kcal/mol). In contrast, the iodine radical is the least reactive of the halogen radicals. In fact, it is so unreactive AH° = 34 kcal/mol) that it is unable to remove a hydrogen atom from an alkane. Consequently, it reacts with another iodine radical and reforms I2. 

Solution We know that the first reaction has to be a radical halogenation because that is the only reaction that an alkane undergoes. Bromination will lead to a greato yield of the desired 2-halo-substituted compound than wiU chlorination because a bromine radical is more selective than a chlorine radical. A nucleophilic substitution reaction forms the alcohol, which forms the target molecule when it is oxidized. 

Show how the following compounds could be prepared Irom 2-methylpropane a. 2-bromo-2-methylpropane b. 2-methyl-2-propanol c. 2-methyl-1-propene 

Ethers are a laboratory hazard because they form explosive peroxides by reacting with O2 when they are exposed to air. We will see that this reaction is similar to the reaction that causes fats to become rancid (Section 13.11). 

A peroxide is a compound with an O—O bond. Because an O—O bond is easily cleaved homolytically, a peroxide forms radicals that then can create new radicals—it is a radical initiator. Thus, the peroxide product of the preceding radical chain reaction can initiate another radical chain reaction— an explosive situation. To prevent the formation of explosive peroxides, ethers contain a stabilizer that traps the chain-initiating radical. Once an ether is purified (in which case it no longer contains the stabilizer), it has to be discarded within 24 hours. 

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This last comment forces one to reconsider the interpretation given to the following accident. A mixture of acetone and isoprene gives rise to the formation of peroxides that detonated spontaneousiy. One can ask oneself what role acetone plays since the presence of acetone is hardly necessary to the formation of explosive peroxides by isoprene in the presence of oxygen (see Hydrocarbons on p.242). 

Prolonged exposure to air may result in the formation of explosive peroxides easily undergoes polymerization (NIOSH, 1997). 

Note Stabilized with 5 to 10 ppm butylated hydroxytoluene (Acros Organics, 2002) to prevent formation of explosive peroxides. 

Note Normally stabilized with 0.025 wt % of 3,5-di-reA-butyl-4-hydroxytoluene to prevent or inhibit formation of explosive peroxides. 

Compared to other classes of organic compounds, ethers have relatively low toxicities. This characteristic can be attributed to the low reactivity of the C-O-C functional group arising from the high strength of the carbon-oxygen bond. Like diethyl ether, several of the more volatile ethers affect the central nervous system. Hazards other than their toxicities tend to be relatively more important for ethers. These hazards are flammability and formation of explosive peroxides (especially with di-isopropyl ether). 

Explosion forms explosive alr vapor mixtures formation of (explosive) peroxides can cause explosion. sealed machinery, ventilation, explosion-proof electrical equipment and lighting, non-sparking tools. in case of fire keep tanks/drums cod by spraying with water. 

NOTE The sodamide should be freshly prepared or obtained from a good commercial source. Long exposure to air and oxygen reduces the effectiveness of the material and may also cause the formation of explosive peroxides, oxides, etc. 

Following a published procedure [1], octene was treated with a solution of perox-yacetic acid in acetic acid for 8 h to form the epoxide, but the reaction mixture was then allowed to stand uncooled overnight. Next morning, when a 3pl sample was injected into a heated GLC injection port, the syringe shattered. This was attributed to formation of diacetyl peroxide during the overnight standing, and its subsequent explosion in the heated port [2],... 

Application of fluorine to aqueous sodium acetate solution causes an explosion, involving formation of diacetyl peroxide. 

An organic sulfur compound containing an acetal function had been oxidised to the sulfone with 30% hydrogen peroxide in acetic acid. After the liquor had been concentrated by vacuum distillation at 50-60°C, the residue exploded during handling. This was attributed to formation of the peroxide of the acetal (formally a gem-diether) or of the aldehyde formed by hydrolysis, but formation and explosion of peracetic acid seems a more likely explanation. 

Ether Air (oxygen) Formation of explosive organic peroxides... 

Mixing sodium percarbonate with acetic anhydride led to explosive shattering of the flask [1], undoubtedly caused by the formation of acetyl peroxide. The name sodium percarbonate has been used indiscriminately to describe 3 different compounds, all of which would react with acetic anhydride to give extremely explosive acetyl peroxide [2], These are sodium monoperoxycarbonate, NaOCO.OONa, [4452-58-8] sodium peroxydicarbonate, NaOCO.OOCO.ONa, [3313-92-6] and sodium carbonate sesqui hydrogen peroxidate, Na0C0.0Na.l,5H202, [15630-89-4],... 

Mixing sodium percarbonate with acetic anhydride led to explosive shattering of the flask [1], undoubtedly caused by the formation of acetyl peroxide. The name sodium... 

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