Peracetic acid (PAA) is a strongly oxidizing chemical that is widely used in oxidants. Here are some of the main applications of peracetic acid in oxidants:
1. Polymerization reaction: In polymerization reaction, peracetic acid can be used as the initiator of free radical polymerization. Free radical polymerization is an important polymerization method that initiates the polymerization of monomer molecules by generating free radicals. Peracetic acid decomposes to produce free radicals during the reaction, thereby promoting the polymerization of monomer molecules to form polymer compounds. This method has high controllability and repeatability when synthesizing polymers, and is widely used in the synthesis of materials such as plastics, rubber, and fibers.
2. Organic synthesis: In the process of organic synthesis, peracetic acid and its salts can be used as oxidants to oxidize certain organic substances into other compounds. Oxidation reaction is a common reaction type in organic synthesis. Through the action of oxidants, the structure and properties of organic matter can be changed. As a strong oxidant, peracetic acid can effectively oxidize unsaturated bonds such as double bonds and triple bonds in organic matter to generate corresponding oxidation products. This reaction has wide applications in the fields of drug synthesis, spice preparation, and dye production.
3. Pharmaceutical manufacturing: In the pharmaceutical industry, peracetic acid can be used to produce certain drugs and drug intermediates. The oxidizing property of peracetic acid makes it play an important role in drug synthesis. It can be used in oxidation reactions to generate specific functional groups in drug molecules. In addition, peracetic acid can also be used to produce pharmaceutical intermediates such as antibiotics and vitamins, providing important raw materials for the pharmaceutical industry. In the pharmaceutical manufacturing process, the use of peracetic acid requires strict control of its concentration and reaction conditions to ensure the safety of the reaction and the quality of the product.
Below are specific application cases with formulas.
It is used for the epoxidation of alkenyl hydroxyl groups, the oxidation of aromatic condensed rings, the N-oxidation of pyridine and the oxidation of C5 and C14 positions of steroids. It can also oxidize navel to azo oxide compounds, iodobenzene to iodobenzene, and phenol to quinone. , thioether becomes sulfoxide and sulfone, etc.
It can oxidize simple alkenes, alkenes containing different functional groups (such as ethers, alcohols, esters, ketones and amino groups, etc.), some aromatic compounds, furans, sulfides, amines, etc. It can also oxidize alkenes in the presence of a catalyst.
Epoxidation of olefins In industry, in order to avoid the possible dangers of using large amounts of this reagent, it is generally prepared in situ. The peracetic acid prepared in this way is widely used for the epoxidation of vegetable oils and fatty acids. Under stirring conditions, gradually add 50% H2O2 to the substrate of an acetic acid solution containing a catalyst amount of sulfuric acid (mass fraction 1%) at about 50°C. The concentration of H2O2 in the solution should remain the same value and no longer increase. Peracetic acid is consumed as it is produced (Formula 1). H2O2 is usually dropped in 2 hours, and the reaction temperature also increases and is maintained at about 60°C until all H2O2 is consumed (about 3 hours). The reaction solution is diluted with water to separate out the water-insoluble epoxide. Since the catalytic sulfuric acid is necessary for the rapid formation of peroxyacetic acid, this in situ method is only suitable for the preparation of epoxides that are stable in the presence of acid catalysts. If the reaction temperature and time are properly controlled, fatty acid epoxides can be obtained in good yields.
For the epoxidation reaction of olefins, peracetic acid in ethyl acetate is a better reagent than acetic acid solution, mainly because a large amount of acetic acid can easily cause epoxide ring opening in subsequent reactions.
Due to the low electron cloud density on the double bond, the reaction of epoxidation of terminal olefins by peracetic acid generally proceeds slowly. The use of some special metal complexes can complete the epoxidation of electron-deficient alkenes . Using the ferric ion chelate {[(phen)2-(HzO)Fe”]2(μ-0)}(Cl04)4 as the catalyst, peroxyacetic acid can react with very high efficiency within 5 minutes at 0°C. The terminal olefin is oxidized with high yield to obtain the epoxidation product (formula 2). Most olefins can be used in this reaction . The activity of this reaction is related to the pH value of the solution. The reaction activity is maximum when pH≤2 Good. The divalent manganese ion complex [Mn”(R,R-mcp)(CF3SO3)2] also has similar activity .
Easily decomposed propenyl epoxide can be prepared by the method shown in Reaction Equation 3 . This method has been successfully used to prepare propenyl epoxides from 1,3-cyclopentadiene , 1,3-heptadiene and 1,3-octadiene.
The epoxidation reaction has regioselectivity and stereoselectivity, and always preferentially occurs on olefinic bonds with high electron cloud density (Equation 4) . The epoxidation of dienes is regioselective and stereoselective, and the reaction site is on the side of the more substituted double bonds with less steric hindrance.
Oxidation of Furans 2,5-disubstituted furans can be oxidized and cleaved by peracetic acid; benzofurans can be oxidized to lactones by peracetic acid (Formula 5) .
Oxidation of Aromatic Compounds Certain substituted aromatic compounds can be efficiently oxidized to quinones by peracetic acid. For example, under the catalysis of Mn(III) or Fe(I) complexes, naphthalene and methylnaphthalene are oxidized by peracetic acid to obtain naphthoquinone (formula 6) .
Ruthenium and osmium catalytic oxidation In the presence of ruthenium trichloride catalyst, olefins react with peracetic acid to form a-ketol. This reaction must be carried out in a two-phase system. Conjugated dienes, allyl azides, α,β-unsaturated esters (Formula 7) can all be oxidized by this reagent.
Other applications In recent years, peracetic acid has also derived some new uses, such as: oxidizing sulfide to sulfoxide ; oxidizing alkylthio group to alkylsulfinyl group . Oxidizing nitrogen heterocycles, such as Pyridine is oxidized to N-amine oxide . Silane is oxidized to hydroxyl (formula 8) .
This article is excerpted from the WuJing database “Peracetic Acid”