Industrial synthesis cumene hydroperoxide

The most important autoxidation used industrially is the synthesis of cumene hydroperoxide from cumene and air (i.e., diluted oxygen) (Figure 1.37). It is initiated by catalytic amounts of dibenzoyl peroxide as the radical initiator (cf. Figure 1.11). The cumyl radical is produced... 

Fig. 1.35. Industrial synthesis of cumene hydroperoxide. In terms of Figure 1.2, this reaction is classified as a "substitution including an addition."...

Autoxidation of cumene (2.61) is the most important industrial synthesis of cumene hydroperoxide (2.62), which gives phenol and acetone. 

Autoxidation is one of the key steps in the industrial synthesis of phenol and acetone from benzene and propylene. In the second step of this synthesis, cumene (isopropylbenzene) is autoxidized to give cumyl hydroperoxide. 

Co-production is still used in many relevant industrial processes. A typical example is the synthesis of phenol via the cumene process, which involves the formation of acetone as by-product. This example is discussed in a more detail later in Chapter 13. Direct oxidation of benzene to phenol using H2O2 is an attractive industrial alternative, but a main motivation is to avoid the formation of acetone, as there is actually excess acetone on the market. The process requires a single step versus three steps in the cumene process, one of which is related to the synthesis of a cumene hydroperoxide intermediate that shows significant problems of safety. There are thus various aspects that make more sustainable the direct synthesis of phenol over the cumene process, but atom economy (or related mass intensity indicators) is not the correct indicator to assess sustainability. 

Among the reactions catalyzed by titanium complexes, the asymmetric epoxidation of allylic alcohols developed by Sharpless and coworkers [752, 807-810] has found numerous synthetic applications. Epoxidation of allylic alcohols 3.16 by ferf-BuOOH under anhydrous conditions takes place with an excellent enantioselectivity (ee > 95%) when promoted by titanium complexes generated in situ from Ti(0/ -Pr)4 and a slight excess of diethyl or diisopropyl (R,R)- or (iS, 5)-tartrates 2.69. The chiral complex formed in this way can be used in stoichiometric or in catalytic amounts. For catalytic use, molecular sieves must be added. Because both (RJ )- and (5,5)-tartrates are available, it is posable to obtain either enantiomeric epoxide from a single allylic alcohol. Cumene hydroperoxide (PhCMe20OH) can also be used in place of ferf-BuOOH. This method has been applied to industrial synthesis of enantiomeric glycidols [811, 812]. 

From Cumene Hydroperoxide. This process illustrates industrial chemistry at its best. Overall, it is a method for converting two relatively inexpensive organic compounds—benzene and propene—into two more valuable ones—phenol and acetone. The only other substance consumed in the process is oxygen from air. Most of the worldwide production of phenol is now based on this method. The synthesis... 

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