Synthesis of Caprolactam and Nylon 6
Charles E. Carraher, Jr. Wright State University Dayton. Ohio 45431
T h i s experiment allows t h e illustration of t h e Beckman rearrangement a n d ring opening reactions. T h e r e a r e a n u m b e r of important ring opening processes. T w o of t h e most i m p o r t a n t involve t h e synthesis of polyepoxys a n d epoxy resins utilizing epoxides such a s epichlorohydrine a n d t h e svnthesis of Nvlon-6 from c a ~ r o l a c t a m .
rangement of oximes to form an amide. It proceeds with a trans migration, the migrating group entering fram the rear as the hydroxyl (or derived) moiety leaves the nitrogen atom, the shift of the group from the carbon to nitrogen occurring as the OH containing portion departs, thus preserving the stereochemical specificity of the reaction. The reaction is typically conducted in eonc. HiS04 or phosphorus pentachlaride containingsolutions. The amine can be obtained utilizing a separate hydrolysis step.
strained four-membered lactam. the lactam maietv being quite labile,
The fact that certain ketones vield oximes that eive onlv one Reekman renrraneement oroduct is due to the oreferential iorohahlv
c=o H-01
Cyclic amides can he formed fram amino acids where the carhonyl (usually as an ester) and amine are separated hy three or fnur carbons. Cyelization to form seven-and higher-memhered cyclic amides occurs only as a minor side product with the major product heing linear amides, under proper conditions leading tn polymeric amides. Easy cyclization to form small membered rings (four and less) does not occur because of the ringstrain present in such rings. Predominance of cvclization to Cnrm lareer rims (seven and lareer) eenerallv does
mines where the intermediate oxime has the aryl group trans to the hydmryl. Most of the about 400 million pounds of caprolactam produced yearly in the U S . alone is utilized in the synthesis of Nylon-6 beginning with eyclohexane which is converted to eyelohexanone which is then made into the oxime finallv usine the Beckman rearrancement
exact equivalence of the two ca-monomers. For instance if there were present about one mole-percent excess of either the diacid or diamine
acid molecules.
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.
to illustrate chemical Principles
Nylon 6
Caprolactam is ordinarily synthesized using either the Reckman or Schmidt rearrangement from eyclohexanone
or its o x h e (generally produced from the hydroxamination of cydohexanone). Here the Beckman rearrangement of the oxime will be used. The Beckman rearrangement involves the stereospecific rear-
More chemists are involved directly and indirectly with the polymer industry than are involved in all the other areas combined. The polymer industry now employs about 800,000 people claiming parity with all of the metal-hased industry in the U.S. The annual production in the U.S. of polymeric materials is about 35 billion pounds which unprocessed, in hulk quantity shows a general price range of about 22 cents a pound for low density polyethylene (about 2 billion pounds per year) to $15 a pound for certain fluoroearhan (such as Teflon) polymers. The 35 billinn pounds represents ahout 175 pounds of plastics for every man, woman, and child per year. There is a need to emphasize "polymers" and "polymer chemistry" above that currently done in most academic institutions. With the already tight time schedule for chemistry majors there is little tendency to'insert polymer related topics a t the expense of much needed theory etc. But polymer related topics can be included without omitting other needed topics hv a iudicious inclusion of oolvmer related examoles to illus-
exercises and illustrations related to the ahove. Chnrlen E. Carraher. Jr. Volume 55, Number 1, January 1978 / 51
T h e following exercise is designed for two 3-hr organic laboratory sessions.
Exercise Caprolactam
i:yrl
