Of isopropyl alcohol

Figure 10.3a shows a simplified fiowsheet for the production of isopropyl alcohol by the direct hydration of propylene. Different reactor technologies are available for the process, and separation and recycle systems vary, but Fig. 10.3a is representative. Propylene... 

Figure 10.3 Outline flowsheet for the production of isopropyl alcohol by direct hydration of propylene. (From Smith and Petela, Chem. Eng., 513 24, 1991 reproduced by permission of the Institution of Chemical Engineers.)...

Mix 40 g. (51 ml.) of isopropyl alcohol with 460 g. (310 ml.) of constant boiling point hydrobromic acid in a 500 ml. distilling flask, attach a double surface (or long Liebig) condenser and distil slowly (1-2 drops per second) until about half of the liquid has passed over. Separate the lower alkyl bromide layer (70 g.), and redistil the aqueous layer when a further 7 g. of the crude bromide will be obtained (1). Shake the crude bromide in a separatory funnel successively with an equal volume of concentrated hydrochloric acid (2), water, 5 per cent, sodium bicarbonate solution, and water, and dry with anhydrous calcium chloride. Distil from a 100 ml. flask the isopropyl bromide passes over constantly at 59°. The yield is 66 g. 

The residue in the flask may be mixed with the aqueous layer of the first distillate, 40 g. of isopropyl alcohol added, and the slow distillation repeated. The yield of crude isopropyl bromide in the second distillation is only slightly less than that obtained in the original preparation. Subsequently most of the residual hydrobromic acid may be recovered by distillation as the constant boiling point acid (126°). 

A further quantity of wopropyl iodide, only slightly less than that obtained in the first distillation, may be prepared by combining the residues in the distilling flask, adding 30 g. (38 ml.) of isopropyl alcohol, and repeating the distillation. Finally, the residues should be distUled and the 67 per cent, constant boiling point acid recovered. 

The above test will detect 1 part of acetone in 500-1000 parts of isopropyl alcohol. The reagent should not be kept for more than 1-2 months since it deteriorates upon keeping. 

The combination of sulfuric acid addition to propene followed by hydrolysis of the resulting isopropyl hydrogen sulfate is the major method by which over 10 lb of isopropyl alcohol is prepared each year m the United States... 

Production of acetone by dehydrogenation of isopropyl alcohol began in the early 1920s and remained the dominant production method through the 1960s. In the mid-1960s virtually all United States acetone was produced from propylene. A process for direct oxidation of propylene to acetone was developed by Wacker Chemie (12), but is not beheved to have been used in the United States. However, by the mid-1970s 60% of United States acetone capacity was based on cumene hydroperoxide [80-15-9], which accounted for about 65% of the acetone produced. 

Direct oxidation of hydrocarbons and catalytic oxidation of isopropyl alcohol have also been used for commercial production of acetone. 

Dehydrogenation of isopropyl alcohol accounts for most of the acetone production not obtained from cumene. The vapor is passed over a brass, copper, or other catalyst at 400—500°C, and a yield of about 95% is achieved (1.09 unit weight of alcohol per unit of acetone) (13). 

Dehydrogenation of Isopropyl Alcohol. In the United States about 4% of the acetone is made by this process, and in Western Europe about 19% (22). Isopropyl alcohol is dehydrogenated in an endothermic reaction. 

Although the selectivity of isopropyl alcohol to acetone via vapor-phase dehydrogenation is high, there are a number of by-products that must be removed from the acetone. The hot reactor effluent contains acetone, unconverted isopropyl alcohol, and hydrogen, and may also contain propylene, polypropylene, mesityl oxide, diisopropyl ether, acetaldehyde, propionaldehyde, and many other hydrocarbons and carbon oxides (25,28). 

The mixture is cooled and noncondensable gases are scmbbed with water. Some of the resultant gas stream, mainly hydrogen, may be recycled to control catalyst fouhng. The Hquids are fractionally distilled, taking acetone overhead and a mixture of isopropyl alcohol and water as bottoms. A caustic treatment maybe used to remove minor aldehyde contaminants prior to this distillation (29). In another fractionating column, the aqueous isopropyl alcohol is concentrated to about 88% for recycle to the reactor. 

A yield of about 95% of theoretical is achieved using this process (1.09 units of isopropyl alcohol per unit of acetone produced). Depending on the process technology and catalyst system, such coproducts as methyl isobutyl ketone and diisobutyl ketone can be produced with acetone (30). 

Hydroxyethyl cellulose (HEC), a nonionic thickening agent, is prepared from alkali cellulose and ethylene oxide in the presence of isopropyl alcohol (46). HEC is used in drilling muds, but more commonly in completion fluids where its acid-degradable nature is advantageous. Magnesium oxide stabilizes the viscosity-building action of HEC in salt brines up to 135°C (47). HEC concentrations are ca 0.6—6 kg/m (0.2—21b/bbl). 

Reactivity is measured by placing a standard quantity, 100 mL, of isopropyl alcohol in a 500- or 1000-mL Dewar flask equipped with a stirrer and a temperature-measuring device. The temperature of the alcohol is adjusted to 30°C. Thirty-six grams of the sample are added and the temperature is observed as a function of time from the addition until a maximum is reached. Reactivity is defined as the temperature rise divided by the time interval to reach this maximum. Other alcohols may also be used for measuring reactivity (30). 

Physical properties of isopropyl alcohol are characteristic of polar compounds because of the presence of the polar hydroxyl, —OH, group. Isopropyl alcohol is completely miscible ia water and readily soluble ia a number of common organic solvents such as acids, esters, and ketones. It has solubiUty properties similar to those of ethyl alcohol (qv). There is a competition between these two products for many solvent appHcations. Isopropyl alcohol has a slight, pleasant odor resembling a mixture of ethyl alcohol and acetone, but unlike ethyl alcohol, isopropyl alcohol has a bitter, unpotable taste. 

Physical and chemical properties of isopropyl alcohol reflect its secondary hydroxyl functionaHty. For example, its boiling and flash poiats are lower than / -propyl alcohol [71-25-8], whereas its vapor pressure and freezing poiat are significantly higher. Isopropyl alcohol bods only 4°C higher than ethyl alcohol. 

Chemical properties of isopropyl alcohol are determined by its functional hydroxyl group in the secondary position. Except for the production of acetone, most isopropyl alcohol chemistry involves the introduction of the isopropyl or isopropoxy group into other organic molecules by the breaking of the C—OH or the O—H bond in the isopropyl alcohol molecule. 

Dehydrogenation. Before the large-scale availabiUty of acetone as a co-product of phenol (qv) in some processes, dehydrogenation of isopropyl alcohol to acetone (qv) was the most widely practiced production method. A wide variety of catalysts can be used in this endothermic (66.5 kj/mol (15.9 kcal/mol) at 327°C), vapor-phase process to achieve high (75—95 mol %) conversions. Operation at 300—500°C and moderate pressures (207 kPa (2.04 atm)) provides acetone in yields up to 90 mol %. The most useful catalysts contain Cu, Cr, Zn, and Ni, either alone, as oxides, or in combinations on inert supports (see Catalysts, supported) (13-16). 

Isopropyl alcohol can be oxidized by reaction of an a,P-unsaturated aldehyde or ketone at high temperature over metal oxide catalysts (28). In one Shell process for the manufacture of aHyl alcohol, a vapor mixture of isopropyl alcohol and acrolein, which contains two to three moles of alcohol per mole of aldehyde, is passed over a bed of uncalcined magnesium oxide [1309-48-4] and zinc oxide [1314-13-2] at 400°C. The process yields about 77% aHyl alcohol based on acrolein. 

Xanthate esters are prepared by reaction of isopropyl alcohol and carbon disulfide [75-15-0]. Isopropyl xanthates have wide use ia mineral flotation (qv) processes, and sodium isopropyl xanthate [140-93-2], C4HyOS2Na, is a useful herbicide for bean and pea fields (see Herbicides) (30). 

Similarly, another important esterification reaction of isopropyl alcohol iavolves the production of tetraisopropyl titanate [546-68-9], a commercial polymeri2ation catalyst, from titanium tetrachloride [7550-45-0] and isopropyl alcohol. 

Isopropyl nitrate [1712-64-7] can be prepared by the reaction of isopropyl alcohol with nitric acid [52583-42-3]. 

The reactants are fed separately iato a stUl, from which the product is continuously removed by distillation (qv) (31). Isopropyl nitrate is a valuable engiae-starter fuel and can be used ia explosives (see Explosives and propellants) (32). The nitrite ester, isopropyl nitrite, can be prepared from the reaction of isopropyl alcohol and either nitrosyl chloride or nitrous acid at ambient temperature (33). The ester is used as a jet engine propellant (30). 

Amination. Isopropyl alcohol can be aminated by either ammonolysis ia the presence of dehydration catalysts or reductive ammonolysis usiag hydrogeaatioa catalysts. Either method produces two amines isopropylamine [75-31-0] and diisopropylamine [108-18-9]. Virtually no trisubstituted amine, ie, triisopropyl amine [122-20-3], is produced. The ratio of mono- to diisopropylamine produced depends on the molar ratio of isopropyl alcohol and ammonia [7664-41-7] employed. Molar ratios of ammonia and hydrogen to alcohol range from 2 1—5 1 (35,36). 

Halogenation of isopropyl alcohol ia aqueous solutioa results ia concomitant oxidatioa. Thus, chlorination at 65°C produces a mixture of chloroacetoae derivatives, chiefly 1,3-dichloroacetoae [534-07-6] and 1,1,3-trichloroacetone [921-03-9] (47,48). Eurther chlorination at 70—I00°C provides... 

The first industrial quantities of isopropyl alcohol were produced in 1920 in the world s first petrochemical plant, owned by Standard Oil (Exxon)... 

Company (Bayway, New Jersey). This was followed in 1921, by the start-up of isopropyl alcohol production in Clendenin, West Virginia, by the Carbide and Carbon Chemicals (Union Carbide) Corporation. The Shell Oil Company began production in the 1930s at Dominguez, California (55). These three companies are the principal domestic manufacturers as of the mid-1990s. 

---