Perpropionic acid

In the peracid process (Bayer-Degussa technology916) propionic acid is oxidized by hydrogen peroxide in the presence of H2S04 to yield perpropionic acid, which, in turn, is used to oxidize propylene to propylene oxide. The peracetic acid process (Daicel technology ) employs a mixture of acetaldehyde, ethyl acetate, and... 

However, there was clear evidence for elution of Co from the resin during reaction. Since leaching of Co was promoted by the water formed in the autoxidation, some acetic anhydride was added to trap the water. Even then, leaching remained substantial, and the anhydride caused some polymerization. Clearly, since acetic acid is a corrosive medium and dissolves Co compounds well, it is probably impossible to find a supported equivalent of Co catalysis in acetic acid. Similar problems of leaching by acid might arise in the autoxidation of propionaldehyde to give perpropionic acid with Co- or Mn-exchanged resins as catalysts (169). 

The in situ generation of performic and peracetic acids has an important application in producing epoxidized soya bean oil (ESBO), a plasticizer and stabilizer. The acetic acid is often re-cycled. Technology for the manufacture of propylene oxide98 and of epichlorohydrin" using internal cycle systems for peracetic or perpropionic acids has also been developed. 

Pentane-1,2-diol is an important intermediate for the production of fungicides125 and can be continuously prepared by reacting pent-l-ene with a solution of perpropionic acid in benzene, and subsequent hydrolysis of the epoxide.126 The diol yield of 92% from the alkene is much higher than with performic acid (Figure 3.26).116... 

Figure 3.26 Hydroxylation of pent-l-ene using perpropionic acid.

In the procedures to date, the most frequent epoxidizing agent has been perbenzoic acid bearing an electron-attracting substituent. The use of p-methoxy-carbonylperbenzoic acid prepared by photooxidative means has been reported. In industrial syntheses, in situ performic acid, peracetic acid, and perpropionic acid °have been utilized in a two-phase solvent. 

The ability to stabilize is also part of green chemistry, for, if things last longer, there will be less need to replace them, and overall consumption will go down. Perpropionic acid can be stabilized by a-cyclodextrin so that 97% remains after 50 days at room temperature.228 Without the cyclodextrin 5% decomposes in just 11 days. The material may be useful for bleaching and disinfection. Some artificial food colors are of questionable toxicity. Some have already been removed from the market. Natural colors offer alternatives, but often lack the necessary resistance to heat and low pH. If cyclodextrins can stabilize colors, such as the red in beet juice, there might be no further need for the artificial colors. 

Although many peroxide compounds are suitable for this reaction, for economic reasons their choice is restricted to f-butyl and ethylbenzene hydroperoxides for the first type of co-reactant, and to peracetic and perpropionic acids for the second. 

See u-nder Perpropionic Acid. Di>n-propylacetaldehyde (l-Propylmler-aldehyde)... 

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