A- caprolactam

In 1993, worldwide phenol production was more than 5.2 million metric tons (1). The predominant uses of phenol are in phenoHc resins (qv), bisphenol A, caprolactam (qv), aniline, and alkylphenols (qv). 

Acetic acid Acrylic acid Adipic acid Benzene Biphenyl Bisphenol-A Caprolactam Chloroacetic acid p-Chloro toluene p-Cresol... 

Ammonium sulfate is produced as a caprolactam by-product from the petrochemical industry, as a coke by-product, and synthetically through reaction of ammonia with sulfuric acid. Only the third process is covered in our discussion. The reaction between anunonia and sulfuric acid produces an ammonium sulfate solution that is continuously circulated through an evaporator to thicken the solution and to produce ammonium sulfate crystals. The crystals are separated from the liquor in a centrifuge, and the liquor is returned to the evaporator. The crystals are fed either to a fluidized bed or to a rotary drum dryer and are screened before bagging or bulk loading. 

In die case of nylon-6,6 waste recycled by ammonolysis, nylon is treated with ammonia in die presence of a phosphate catalyst. Reaction occurs at 330°C and 7 MPa. Distillation of die reaction mixture produces ammonia which is recycled and three fractions containing (a) caprolactam, (b) HMDA and aminocaproni-trile, and (c) adiponitrile. Aminocapronitrile and adiponitrile are hydrogenated to yield pure HMDA, and die caprolactam is eidier converted to aminocapronitrile by further ammonolysis or distilled to produce pure caprolactam. The HMDA produced by this process is extremely pure (>99.8).1 The main impurities are aminomediylcyclopentylaniiiie and tetrahydroazepine, which are expected to be removed more effectively in the larger distillation columns employed in the larger plants. 

The polycaprolactam waste is contacted with superheated steam in the absence of added catalyst at a temperature of about 250 to 400C and a pressure in the range of about 1.5 to 100 atm. and substantially less than the saturated vapour pressure of water at the temperature at which a caprolactam-containing vapour stream is formed. The resulting caprolactam may then be used in the production of engineered resins and fibres. 

Rosa Llusar was born on September 20th, 1960 in Almenara (Spain). She studied chemistry at the University of Valencia (Spain) where she graduated in 1983 with the highest honors. Her doctorate work was devoted to the chemistry of cubane-type molybdenum and tungsten sulfides and she received Ph.D. degrees from Valencia University in 1987 and from Texas A M University (USA) in 1988, under the guidance of Prof. F. Albert Cotton. After working in the Research and Development Department of a Caprolactam Production Plant in Castello (Spain) for three years, she spent one year (1992) with Prof John D. Corbett at the... 

Figure 23.3 Examples of monomers used in the polymerization of nylons a) caprolactam, b) adipic add and c) hexamethylene diamine...

The related dirhodium(II) a-caprolactamate (cap) complex [Rh2(p--cap)4] undergoes a one-electron oxidation process at quite a lower potential (11 mV) than the acetate complex (1170 mV). In agreement with the Kochi hypothesis, the a-caprolactamate complex has recently been found to be an exceptional catalyst for the allylic oxidation of alkenes under mild conditions. A wide range of cyclohexenes, cycloheptenes, and 2-cycloheptenone (Eq. 5) are rapidly converted to enones and enediones in 1 h with only 0.1 mol % of [Rh2( x-cap)4] and yields ranging from 60 to 90%, in the presence of potassium carbonate [34]. 

If any base whose basicity exceeds the basicity of the caprolactam anion is applied, this kind of neutralization reaction results in formation of caprolactam salt, i. e. practically a metal salt of caprolactam. As far as the simultaneously formed component B-H does not interfere to the further catalytic action, especially if this compound is higly volatile and can be easily removed before having opportunity of such interference, the same result is obtained no matter what sort of base was used. Thus, extremely strong bases as alkali metals (7, 15, 18—22, 31, 42, 43, 46, 47, 49—51, 58, 71, 72, 100, 101), other strongly elektropositive metals (42), metal hydrides (12,31, 32, 51, 52) or metal amides react in a smooth way according the above scheme. The same result i. e. the formation of a caprolactam salt is obtained starting with relatively weak bases as alkali hydroxides (1, 5, 6, 10, 12, 13, 16—19, 28, 29, 33—35, 37—41,44, 45, 51, 54, 60, 64, 70—72, 78, 79, 100, 102) or alcoxides (9, 45), leading to an equilibrium... 

Phenol is used in the manufacture of formaldehyde resins, bisphenol A, caprolactam, aniline, xylenols, and alkylphenols. Phenol-formaldehyde polymers (phenolic resins) have a primary use as the adhesive in plywood formulations. The use of phenol in detergent synthesis to make alkylphenols is an important aspect of phenol utility. 

Process Economics Program Report SRI International. Menlo Park, CA, Isocyanates IE, Propylene Oxide 2E, Vinyl Chloride 5D, Terephthalic Acid and Dimethyl Terephthalate 9E, Phenol 22C, Xylene Separation 25C, BTX, Aromatics 30A, o-Xylene 34 A, m-Xylene 25 A, p-Xylene 93-3-4, Ethylbenzene/Styrene 33C, Phthalic Anhydride 34B, Glycerine and Intermediates 58, Aniline and Derivatives 76C, Bisphenol A and Phosgene 81, C1 Chlorinated Hydrocarbons 126, Chlorinated Solvent 48, Chlorofluorocarbon Alternatives 201, Reforming for BTX 129, Aromatics Processes 182 A, Propylene Oxide Derivatives 198, Acetaldehyde 24 A2, 91-1-3, Acetic Acid 37 B, Acetylene 16A, Adipic Acid 3 B, Ammonia 44 A, Caprolactam 7 C, Carbon Disulfide 171 A, Cumene 92-3-4, 22 B, 219, MDA 1 D, Ethanol 53 A, 85-2-4, Ethylene Dichloride/Vinyl Chloride 5 C, Formaldehyde 23 A, Hexamethylenediamine (HMDA) 31 B, Hydrogen Cyanide 76-3-4, Maleic Anhydride 46 C, Methane (Natural Gas) 191, Synthesis Gas 146, 148, 191 A, Methanol 148, 43 B, 93-2-2, Methyl Methacrylate 11 D, Nylon 6-41 B, Nylon 6,6-54 B, Ethylene/Propylene 29 A, Urea 56 A, Vinyl Acetate 15 A. 

Palladium hydrogenates arenes at elevated T (>90 C) and P (>20 X 10 kPa), but still finds industrial applications such as the preparation of cyclohexanecarboxylic acid, a caprolactam intermediate, by hydrogenation of benzoic acid in quantitative yield . Water increases the reduction rate over Pd catalysts, and strained rings can be hydrogenated over palladium-on-carbon in alcohol at Rt and P [equation (a)] . Compound 1 is readily hydrogenated the less strained compound 2 is inert. 

Heath. A, Caprolactam Grom totaenewithout ammonium sulfate". Chem. Engng, 81 (15) 70-71 (1974). NYPRO, a lesson not to be forgotten. Chemical Age, 14-15 (23 May 1975). 

The new primary amine anion (HI), unlike the lactam anion (II), is not stabilized by conjugation with a carbonyl group. It is therefore highly reactive and, once it is formed, it undergoes a rapid proton-abstraction reaction with a caprolactam monomer producing the dimer compound A -caproylcaprolactam (TV), which is a //-acyllactam, and regenerating the lactam anion (II) ... 

The interest in 1,3-butadiene hydroformylation is the atom-efficient green route for producing /1, y-unsaturated aldehyde and 1,6-hexanedial (adipaldehyde), which is a valuable precursor for producing a-caprolactam and adipic acid/hexamethylene-1, 6-diamine (HMDA) as key monomers in nylon-6 and nylon-6,6 manufacture. 

So, while the above structure commonly represents propiolactam, in this section it can mean any lactam, like a caprolactam, valerolactam, etc. Thus, the reaction can be shown as follows ... 

Figure 7-2 shows, for example, crystallization of ammonium sulfate from a crude solution, obtained from a caprolactam process, in a three stage evaporation crystallization unit [7.16], The unsaturated crude solution is fed to a crystal washer (1), in which... 

Fig. 7-2. Flow sheet of a three-stage crystallization unit of ammonium sulfate from a crude solution of a caprolactam process.

With the cationic initiators known, only low yields and degrees of polymerization are obtained with a-caprolactam. Therefore the cationic polymerization process is not used commercially. Low yields and low degrees of polymerization presumably result from formation of amidine structures ... 

Ogawa et al. have reported the cyclodehydration of 6-aminocaproic acid adsorbed on zeolite, silica gel or alumina in refluxing toluene to yield a-caprolactam [85]. 

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