Propylene from isopropanol

The production of isopropanol from propylene occurs by either a direct hydration reaction (the newer method) or by the older sulfation reaction followed by hydrolysis. 

Diisopropyl sulfate is an intermediate in the indirect hydration (strong- or weak-acid) process for the preparation of isopropanol from propylene. It has no other known industrial use. No data were available on levels of occupational exposure to diisopropyl sulfate (lARC, 1992). 

Three major non-polymer propylene derivatives are isopropanol, acetone, and acrylic acid. Isopropanol (isopropyl alcohol) is used mainly as a solvent. It has been made from propylene by reaction with sulfuric acid and water for at least the last 75 years, making its manufacture the oldest, still-running commercial organic chemical process. It is used in household rubbing alcohol because, unlike ethanol, it is unfit for human consumption even in small amounts. About 25 % of the isopropanol produced is used for making acetone, in competition with a route based on isopropylbenzene. 

Some AvaUahle Data. A brief list of extractive distillation processes of actual or potential commerical value is in Table 13.7 the column of remarks explains why this mode of separation is adopted. The leading applications are to the separation of closeboiling aromatic, naphthenic, and aliphatic hydrocarbons and of olefins from diolefins such as butadiene and isoprene. Miscellaneous separations include propane from propylene with acrylonitrile as solvent (DuPont, U.S. Pat. 2,980,727) and ethanol from isopropanol with water as solvent [Figure 13.23 (b)]. 

FIGURE 19.1 Simplified flowsheet for isopropanol production from propylene. (Adapted from Lowenheim and Moran [5].)... 

From the thermodynamic and kinetic standpoints, dehydrogenation is favoured by an increase in temperature. At 325 C and atmospheric pressure, the theoretical conversion reaches nearly 98 per cent It should be practically total at 525°C. In fact a number of side reactions occur aUhese temperatures, including the dehydration of isopropanol to propylene. 

Other routes for obtaining glycerol are also based on propylene. It can be produced from allyl chloride or from acrolein and isopropanol (see following sections). 

By far the largest prodn of acet in the USA is from petroleum-derived propylene by way of isopropanol (Refs 31 48). Another method is to pass acetylene and steam over FeaOj-ZnO catalyst at elevated tempsfRef 48). In Germany acet was produced in 95% yield from AcOH by a vapor-phase catalytic process using a cerium oxide catalyst at 400 Ref 31) There are also other methods of prepn(Refs 1,2,3,4,10,14,31,33,42,47, ... 

The slurry process is the oldest and still widely used method for manufacturing polymers of ethylene, propylene and higher a-olefins. In this process, the monomer dissolves in the polymerisation medium (hydrocarbon diluent) and forms a solid polymer as a suspension containing ca 40 wt-% of the polymer the polymerisation occurs below the melting point of the polymer. In slurry polymerisation, the temperature ranges from 70 to 90 °C, with the ethylene pressure varying between 7 and 30 atm. The polymerisation time is 1-4 h and the polymer yield is 95-98 %. The polymer is obtained in the form of fine particles in the diluent and can be separated by filtration. Removal of the catalyst residues from the polymer can be achieved by the addition of alcohol (isopropanol, methanol), followed by recovery and extraction of the catalyst residues. The polymer is freed from diluent by centrifuging and then dried. In the case of polypropylene manufacture, the atactic fraction remains in the diluent [28,37]. 

Lactylated Fatty Acid Esters of Glycerol and Propylene Glycol occur as a substance that varies in consistency from a soft solid to a hard, waxy solid. They are a mixture of partial lactic and fatty acid esters of propylene glycol and glycerin produced by the lactylation of a product obtained by reacting edible fats or oils with propylene glycol. They are dispersible in hot water, and are moderately soluble in hot isopropanol, in chloroform, and in soybean oil. 

The introduction of an inert liquid may have an advantage in equilibrium-controlled reversible reactions. Tf the product is selectively more soluble in the liquid than the reactant, then the composition of the reacting mixture shifts from the equilibrium composition and better conversions are obtained. Zabor et al.58 have shown this to be the case during equilibrium conversion of propylene to isopropanol in the presence of an excess of water and tungsten oxide catalyst. Isopropanol is selectively more soluble in water than propylene, causing reduction of product concentration at the catalyst surface and resulting in better conversions of propylene. 

By far the largest prodn of acet in the USA is from petroleum-derived propylene by way of isopropanol (Refs 31 48). Another method is to pass acetylene and steam over Fe 0)-Zn0 catalyst at elevated temps(Ref... 

Any higher alcohols that may have formed in the process from traces of higher olefins present in the propylene feed are absorbed from the azeotrope into mineral oil, in which isopropanol is insoluble. Pure isopropanol is obtained by ternary distillation of the cleaned water azeotrope with the appropriate proportion of added di-isopropyl ether. The ternary azeotrope (Table 19.2) is the top product from the column, and pure isopropanol is removed from the bottom (see Section 16.4 for related information). 

The conversion can be carried out in two separate reactors or in a single one in tbe gas phase. In the most widely used processes, a liquid C3 cut (propylene content above 65 per cent weight) is treated with 70 to 75 per cent weight sulfuric add between 2 and 3.106 Pa absolute at ambient temperature. Isopropanol selectivity ranges from 90 to 95 molar per cent, depending on the propylene concentration in the feed. 

Acetate, CaHHOy needles from alcohol, mp 149-151 . Mi +22 (alcohol). Soly (g/100 ml of soln) carbon tetrachloride 50. petr ether l.O, ethyl acetate 7.9 acetone 2.7 chloroform 55.0 ethanol 2.5 benzene 26.0 isopropanol 2.0. Soly (g/100 ml of solvent) propylene glycol 0.1 dioxane 20.2 benzyl alcohol It.] benzyl benzoate 9.1. 

Crystals from water, mp 160. Practically insol in water. Sol in ethanol, isopropanol, propylene glycol, ether, benzene, toluene. Hydrolyzed by alkali. 

S, .S. .S )-Tri(isopropanol)arnine (14) is an efficient ligand for zirconium catalysts for cnantio-selective ring opening of epoxides with silyl azides (Section C.). It can be obtained either by the reaction of the commercially available starting materials ( + )-(5)-l-amino-2-propanol [(S)-alan-inol] and (-)-(5)-propylene oxide18, or directly from pure (iS)-propylene oxide and ammonia ... 

Propylene is obtained from refining of gasoline and thermal or catalytic cracking of hydrocarbons. It is used to produce polypropylene (plastic) and in the manufactnre of acetone, isopropanol, cumene, and propylene oxide. 

---