Of e-caprolactam

The material, Hostamid, LP700, is said to be a melt polycondensate of the diamines (I) and (II) above with terephthalic acid and up to 70% of e-caprolactam but has never been commercially marketed. 

Sodium hydroxide has been used successfully as a catalyst for the base-catalyzed depolymerization of nylon-6. At 250°C, a pressure of 400 Pa, and a sodium hydroxide content of 1%, the yield of e-caprolactam was 90.5%.49... 

Anionic copolymerization of e-caprolactam and cj-caprylolactam was also reported212,213. Organosiloxane copolymers can be prepared from two different cyclics by using acid or base catalysts214. ... 

From the kinetic viewpoint the polymerizability of 61 is considered to be higher than that of e-caprolactam, which is polymerized usually at temperatures above 135 °C63,64 Thermodynamically, the polymerization of 61 appears to be more favored than that of a-pyrrolidone, for which no polymerization is observed in THF63-65 The higher polymerizability of 61 may be attributed not only to its highly strained bicyclic structure but also to the activation of the anion 66 by the... 

Future developments are expected not only to yield a greater understanding of the mechanisms of many photochemical reactions, but also to provide a means for the adaptation of these reactions to large-scale industrial syntheses. A glimpse of the latter is seen in the production of e-caprolactam (Nylon 6 monomer) by the Toyo Rayon Company using the photonitrosation of cyclohexane. In this process nitrosyl chloride is cleaved by light and the following sequence of reactions takes place ... 

Methoxyphenylurea, 31,10,13 Methyl -acetylbenzoate, 32, 81 Methyl acrylate, 30, 65 32, 86 y-Methylallophanate, 32, 62 Methylamine, 30, 60 4 -Methyl-2-aminobenzophenone, 32,12 N-Methylaniline, 30, 62 31,110 N-Methylarylamines, preparation by reductive alkylation, 30, 59, 60 Methylation, of e-caprolactam, 31, 72 of quinacetophenone, with dimethyl sulfate, 31, 91 with methyl iodide, 31, 90 2-Methyl-3,l,4-benzoxaz-4-one, 32, 12 N-Methyl-a-bromo-n-butyranilide, 30, 63... 

Polyamide 6 is produced by ring opening polycondensation of e- caprolactame. If no other reactants are used, the polymer chains contain one carboxylic acid and one amine end group. 

Sommelet, 30, 67 Alizarin indicator, 37, 33 Alkylation, of acetylene, 30, 15 of aniline with triphenylcarbinol, 30, 5 of e-caprolactam with dimethyl sulfate,... 

Ragaini [86] has reported that the ring opening polymersiation of e-caprolactam (nylon 6, Fig. 5.43), in the presence of ultrasound, takes place without the need for added water and yields larger molar masses in shorter reaction times and at lower reaction temperatures than conventional polymerisation. 

Lysine and its derivatives are used for the preparation of e-caprolactams. From L-Lys or its ester, (5)-3-aminohexahydro-2//-azepin-2-one is prepared (43JCS39 57JCS4830 78S614 79JOC4841 80TL2443). 

Preparation of Linear and Star Nylon 6. The star-branched initiator, trimesoyl-tris-caprolactam (TTC) 6 was synthesized from the commercially available trimesoyl chloride 5 using the route shown in Figure 2. (6) Trimesoyl acid chloride in benzene was slowly added to a stirring solution of e-caprolactam, pyridene, and benzene. After addition was complete, the solution was heated to 70° C for 30 minutes to assure conversion to the initiator species. Single and difunctional analogs were synthesized using the same reaction scheme for direct comparison of the star-branched and linear aromatic initiator systems. 

Reduction of 5,5-dimethyl-2-pyrrolidone with 3 mol of lithium aluminum hydride by refluxing for 8 hours in tetrahydrofuran gave 2,2-dimethylpyrrol-idine in 67-79% yields [1123]. Reduction of e-caprolactam was accomplished by heating with sodium bis(2-methoxyethoxy)aluminum hydride [544], by successive treatment with triethyloxonium fiuoroborate and sodium borohydride [1121], and by refluxing with borane-d ras. )a.y sulfide complex [1064]. 

Hohensee F On pharmacological and physiological action of e-caprolactam (Ger) Faser-forsch Textiltech 8 299-303, 1951... 

Currently, cyclohexanone oxime is synthesized starting from cyclohexanone and hy-droxylamine (Route A, Scheme 30) or by photonitrosation of cyclohexane with NOCl (PNC process. Route B, Scheme 30). Of these approaches. Route A is most often employed and accounts for about 70% of the total production of e-caprolactam worldwide. However, this method has several drawbacks. ... 

The most notable apphcation of the Beckmann rearrangement is in the industrial production of e-caprolactam from cyclohexanone (or its oxime), which is used as monomer for the polymerization to a polyamide for the production of synthetic fibres (for example, nylon 6). 

The production of the nylon precursor e-caprolactam via the Beckmann rearrangement is one of the largest industrial processes worldwide. There are a large number of synthetic routes to e-caprolactam, most of which need to be improved because, without exception, all are multistage processes that produce large amounts of by-products, primarily ammonium sulfate. Due to its industrial application, the improvement of the Beckmann rearrangement of e-caprolactam was the aim of several smdies and a lot of scientific papers, patents and book chapters have been published on this topic during the last century. 

The classical production of e-caprolactam is based on cyclohexanone oxime and on its Beckmann rearrangement. For this step, aU manufacmrers use fuming sulfuric acid or oleum, sometimes enriched with more sulfur trioxide than present anyway in the oleum, to increase the rate of the rearrangement process. 

The rearrangement was done in similar ways by different caprolactam producers, and the differences can only be found in the purification processes. With the formation of ammonium sulfate being the most important problem for the producers of e-caprolactam, and due to the rising costs of its removal, many companies searched for new possibilities to produce caprolactam. There are some important industrial processes avoiding the cyclohexanone oxime as an intermediate product. 

Apart from the uses in the production of e-caprolactam, the Beckmann rearrangement has been used industrially in the synthesis of various APIs (Active Pharmaceutical Ingredient) or other compounds with economical value (essentially monomers for the production of polymers). A survey of the bulk reaction scaled in the GMP facilities at... 

Hydrolytic polymerization of e-caprolactam to form nylon 6 (Sec. 2-8f) is carried out commercially in both batch and continuous processes by heating the monomer in the presence of 5-10% water to temperatures of 250-270°C for periods of 12 h to more than 24 h [Anton and Baird, 2002 Zimmerman, 1988]. Several equilibria are involved in the polymerization [Bertalan et al., 1984 Sekiguchi, 1984]. These are hydrolysis of the lactam to e-amino-caproic acid (Eq. 7-56), step polymerization of the amino acid with itself (Eq. 7-57), and initiation of ring-opening polymerization of lactam by the amino acid. The amino acid is... 

The overall rate of conversion of e-caprolactam to polymer is higher than the polymerization rate of e-aminocaproic acid by more than an order of magnitude [Hermans et al., 1958, I960]. Step polymerization of e-aminocaproic acid with itself (Eq. 7-57) accounts for only a few percent of the total polymerization of e-caprolactam. Ring-opening polymerization (Eq. 7-58) is the overwhelming route for polymer formation. Polymerization is acid-catalyzed as indicated by the observations that amines and sodium e-aminocaproate are poor initiators in the absence of water and the polymerization rate in the presence of water is first-order in lactam and second-order in COOH end groups [Majury, 1958]. 

Aliphatic polyamides of e-caprolactam (Nylon-6) possess great importance as fibers and plastics. 

Bulk Polymerization of e-Caprolactam with Anionic Initiators (Flash Polymerization)... 

PHOTO-INDUCED RING EXPANSION OF l-TRIISOPROPYLSILYLOXY-1-AZIDOCYCLOHEXANE PREPARATION OF e-CAPROLACTAM [2 Azepin-2-one, hexahydro- from Silane, [(1-azidocyclohexyl)oxy]tris(1-... 

Polymerization by a ring-opening reaction is confined to cyclic monomers which contain at least one heteroatom. The mechanism is very often a polyaddi-tion-type with a product which has a polycondensation-type character. For example, ethylene oxide and other cyclic esters can be polymerized into linear chains by this type of reaction. An even more complicated example of this type of polymerization reaction is the polymerization of e-caprolactam into Nylon 6 (PA 6). 

In a well-ventilated hood, to a vigorously stirred solution of 11.3 gm (0.1-mole) of e-caprolactam and 23 gm (0.3 mole) of technical grade sodium nitrite in 50 ml of water, cooled in an ice-salt bath, is added dropwise 25 ml of concentrated hydrochloric add at such a rate that the temperature never exceeds —10°C. The reaction mixture is then cooled in a refrigerator for 2 hr. Impurities are rapidly removed by filtration and the product is extracted with ether. 

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