Adipic main producers

Two-step synthesis of sugar-containing polyesters by lipase CA catalyst was reported (Scheme 13)." Lipase CA catalyzed the condensation of sucrose with an excess of divinyl adipate to produce sucrose 6,6 -O-divinyl adipate, which was reacted with a,oo-alkylene diols by the same catalyst, yielding polyesters containing a sucrose unit in the main chain. This method conveniently affords... 

Cyclo-paraffins, also referred to as naphthenes, are mainly produced by dehydrogenation of their equivalent aromatic compounds such as the production of cyclohexane by dehydrogenation of benzene. Cyclohexane is mostly used for the production of adipic acid and nylon manufacturing (Rudd et al., 1981). 

Caprolactam (world production of which is about 5 million tons) is mostly produced from benzene through three intermediates cyclohexane, cyclohexanone and cyclohexanone oxime. Cyclohexanone is mainly produced by oxidation of cyclohexane with air, but a small part of it is obtained by hydrogenation of phenol. It can be also produced through selective hydrogenation of benzene to cyclohexene, subsequent hydration of cyclohexene and dehydrogenation of cyclohexanol. The route via cyclohexene has been commercialized by the Asahi Chemical Company in Japan for adipic acid manufacturing, but the process has not yet been applied for caprolactam production. 

It has been known since the early 1950s that butadiene reacts with CO to form aldehydes and ketones that could be treated further to give adipic acid (131). Processes for producing adipic acid from butadiene and carbon monoxide [630-08-0] have been explored since around 1970 by a number of companies, especially ARCO, Asahi, BASF, British Petroleum, Du Pont, Monsanto, and Shell. BASF has developed a process sufficiendy advanced to consider commercialization (132). There are two main variations, one a carboalkoxylation and the other a hydrocarboxylation. These differ in whether an alcohol, such as methanol [67-56-1is used to produce intermediate pentenoates (133), or water is used for the production of intermediate pentenoic acids (134). The former is a two-step process which uses high pressure, >31 MPa (306 atm), and moderate temperatures (100—150°C) (132—135). Butadiene,... 

Until the mid-1950s the main raw material source for the European plastics industry was coal. On destructive distillation coal yields four products coal tar, coke, coal gas and ammonia. Coal tar was an important source of aromatic chemicals such as benzene, toluene, phenol, naphthalene and related products. From these materials other chemicals such as adipic acid, hexamethylenedia-mine, caprolactam and phthalic anhydride could be produced, leading to such important plastics as the phenolic resins, polystyrene and the nylons. 

The main use of acrolein is to produce acrylic acid and its esters. Acrolein is also an intermediate in the synthesis of pharmaceuticals and herhicides. It may also he used to produce glycerol hy reaction with isopropanol (discussed later in this chapter). 2-Hexanedial, which could he a precursor for adipic acid and hexamethylene-diamine, may he prepared from acrolein Tail to tail dimenization of acrolein using ruthenium catalyst produces trans-2-hexanedial. The trimer, trans-6-hydroxy-5-formyl-2,7-octadienal is coproduced. Acrolein, may also he a precursor for 1,3-propanediol. Hydrolysis of acrolein produces 3-hydroxypropionalde-hyde which could he hydrogenated to 1,3-propanediol. ... 

Adipic acid is of considerable importance since it is a precursor to nylon and polyester, which are extensively used in many products. Between two and three million tonnes are produced worldwide each year. Currently, its main method of manufacture is a costly, multistep process involving concentrated nitric acid. Nitrous oxide is produced as a by-product in such quantities that they measurably contribute to global warming and ozone depletion [24], A cleaner alternative to this process is clearly highly desirable. 

Oxidation is the first step for producing molecules with a very wide range of functional groups because oxygenated compounds are precursors to many other products. For example, alcohols may be converted to ethers, esters, alkenes, and, via nucleophilic substitution, to halogenated or amine products. Ketones and aldehydes may be used in condensation reactions to form new C-C double bonds, epoxides may be ring opened to form diols and polymers, and, finally, carboxylic acids are routinely converted to esters, amides, acid chlorides and acid anhydrides. Oxidation reactions are some of the largest scale industrial processes in synthetic chemistry, and the production of alcohols, ketones, aldehydes, epoxides and carboxylic acids is performed on a mammoth scale. For example, world production of ethylene oxide is estimated at 58 million tonnes, 2 million tonnes of adipic acid are made, mainly as a precursor in the synthesis of nylons, and 8 million tonnes of terephthalic acid are produced each year, mainly for the production of polyethylene terephthalate) [1]. 

D-Glucaric acid, directly produced by nitric oxidation of glucose or starch, is usually isolated as its 1,4-lactone. The technical barrier to its large-scale production mainly includes development of an efficient and selective oxidation technology to eliminate the need for nitric acid as the oxidant. Because it represents a tetrahydroxy-adipic acid, D-glucaric acid is of similar utility as adipic acid for the generation of polyesters and polyamides (see later in this chapter). 

Adipic acid is a straight-chain dicarboxylic acid that exists as a white crystalline compound at standard temperature and pressure. Adipic acid is one of the most important industrial chemicals and typically ranks in the top 10 in terms of volume used annually by the chemical industry. Worldwide, approximately 2.5 million tons of adipic acid are produced annually. Adipic acid s main use is in the production of 6,6 nylon. It is also used in resins, plasticizers, lubricants, polyurethanes, and food additives. 

In a side-reaction 10-15% carboxylic acids are produced by oxidative cleavage of the ketone enolates. The cleavage is favoured by higher temperatures e.g. cyclo-hexanol leads to 80% cyclohexanone and 16% adipic acid at 25 °C, whilst at 80 °C 5% ketone and 42% diacid are found. These acidic by-products are easily separated, since they remain in the alkaline solution during workup. The oxidation of 6 gave the acetal 7 as main product (28%) together with 4% of the ketone 8 and 56% of unchanged 6. The acetal 7 is probably formed by nucleophilic addition of the alcohol 6 at the activated triple bond of ketone 8. 

Oxidation of Cyclohexane. The synthesis of cyclohexanol and cyclohexanone is the first step in the transformation of cyclohexane to adipic acid, an important compound in the manufacture of fibers and plastics. Cyclohexane is oxidized industrially by air in the liquid phase to a mixture of cyclohexanol and cyclohexanone.866 872-877 Cobalt salts (naphthenate, oleate, stearate) produce mainly cyclohexanone at about 100°C and 10 atm. The conversion is limited to about 10% to avoid further oxidation by controlling the oxygen content of the reaction mixture. Combined yields of cyclohexanol and cyclohexanone are about 60-70%. 

In the Dupont process, cyclohexane is reacted with air at 150 °C and 10 atm pressure in the presence of a soluble cobalt(II) salt (naphthenate or stearate). The conversion is limited to 8-10% in order to prevent consecutive oxidation of the ol-one mixture. Nonconverted cyclohexane is recycled to the oxidation reactor. Combined yields of ol-one mixture are 70-80%.83,84,555 The ol-one mixture is sent to another oxidation reactor where oxidation by nitric acid is performed at 70-80 °C by nitric acid (45-50%) in the presence of a mixture of Cu(N03)2 and NH4V03 catalysts, which increase the selectivity of the reaction. The reaction is complete in a few minutes and adipic acid precipitates from the reaction medium. The adipic acid yield is about 90%. Nitric acid oxidation produces gaseous products, mainly nitric oxides, which are recycled to a nitric acid synthesis unit. Some nitric acid is lost to products such as N2 and N20 which are not recovered. 

Adipic acid [HOjC E COjH], the main product of cyclohexane, is reacted with hexamethylene diamine to produce nylon-6,6, a very strong synthetic fiber. Most carpets are made of nylon, as are many silklike garments, some kinds of rope, and many injection-molded articles. 

Adipic acid is mainly used to produce nylon-6,6, a synthetic polyamide used in clothing, in the automobile industry, and in construction it also finds application in polyurethanes, plasticizers, and synthetic lubricants. Manufacture of nylon accounts for 89% of adipic acid consumption in North America, and 55-65% in Western Europe and Japan. 

Separation of benzene/cyclohexane mixture is investigated most extensively. This is not surprising because separation of this mixture is very important in practical terms. Benzene is used to produce a broad range of valuable chemical products styrene (polystyrene plastics and synthetic rubber), phenol (phenolic resins), cyclohexane (nylon), aniline, maleic anhydride (polyester resins), alkylbenzenes and chlorobenzenes, drugs, dyes, plastics, and as a solvent. Cyclohexane is used as a solvent in the plastics industry and in the conversion of the intermediate cyclohexanone, a feedstock for nylon precursors such as adipic acid. E-caprolactam, and hexamethylenediamine. Cyclohexane is produced mainly by catalytic hydrogenation of benzene. The unreacted benzene is present in the reactor s effluent stream and must be removed for pure cyclohexane recovery. 

Reaction between Na(Hg) and acrylic acid (AA) in water, dioxane, or diglyme produces propionic acid (PA) however, when DMSO (containing about 10% water) is used as solvent, adipic acid (ADA) is the main product [48]. 

The hydrodimerization of acrylic acid to adipic acid is a tail-to-tail addition hydrodimerization of methacrylic acid and crotonic acid produces mainly the head-to-head and head-to-tail dimers [48]. 

Oxidation of n-alkanes by Co acetate in acetic acid occurs with a remarkable regioselectivity (rs) at the alkyl acetate as the major product in anaerobic conditions, and 2-alkanone in the presence of oxygen (equations 233 and 234). Cyclohexane is readily oxidized in nitrogen by Co(OAc)3 in acetic acid to mainly cyclohexyl acetate and 2-acetoxycyclo-hexanone. In the presence of oxygen and a high cobalt concentration, adipic acid is the major product formed (equation 235). Oxidation of adamantane by Co(OAc)s and TFA in AcOH preferentially occurs at the tertiary positions, producing 1-adamantyl acetate as the major product. ... 

The readiness with which long-chain polymers crystallize is governed by the structure of the monomer and the linearity of the main chain. In the case of cellulose this relationship is referred to in the next chapter. Linear main chains are produced by the condensation or polymerization of bifunctional monomers which are those in which the uniting groups are such that the molecules can only link up end to end. A good example of this is nylon 66 made by the co-polymerization of adipic acid... 

The synthesis of adipic acid in the laboratory can be carried out by the oxidation of cyclohexene with potassium permanganate (Equation 4.6). The E-factor of this reaction is 2.61, which means that for 1kg of adipic acid 2.61kg waste (mainly Mn02 and KOH) is produced. The atom economy is 27.8%, indicating that only 27.8% of the atoms in the reactants will be incorporated into the product. 

Butane oxidation in the presence of cobalt(III) acetate in acetic acid occurs at temperatures of 100-125 °C. Acetic acid is the reaction product with 83% selectivity (at 80% conversion) [Ij, 17]. These data are markedly different from those observed for butane autoxidation at low initiator concentrations, where temperatures up to 170 °C and higher are required and acetic acid is produced with 40% selectivity. Cyclohexane oxidation in the presence of cobalt(II) acetate in acetic acid gives adipic acid in one step as the main product with 75% selectivity at more than 80% cyclohexane conversion [2b]. The induction period... 

Initially, cyclohexane is oxidized to the intermediate cyclohexyl hydroperoxide, CHHP. Then, the obtained CHHP is decomposed into the desired components cyclohexanone and cyclohexanol however, it is also partly decomposed into undesired by-products. A part of the formed cyclohexanol is further oxidized to cyclohexanone and a part of the formed cyclohexanone is converted to by-products. Part of the cyclohexane oxidation by-products are further destroyed (not shown in this figure). The by-products finally obtained include, in various amounts, acids such as adipic acid, e-hydroxycaproic acid, glutaric acid, succinic acid, valeric acid, caproic acid, propionic acid, acetic acid, formic acid, and noncondensable gases such as CO and CO2. In addition, several esters are formed between mainly cyclohexanol and the various carboxylic acids. The destinations of these by-products are quite diverse and depend on the producer for example, some of these byproducts are fed to combustion units for heat recovery purposes, while others are used as feedstock for chemicals such as 1,5-pentanediol, 1,6-hexanediol (HDO), and caprolactone. In general cyclohexanol is recovered from esters in a biphasic saponification step. 

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