THERMAL ALKYLATION OF AMBIDENTATE LACTAMS WITH 2-(PERFLUOROALKYL)-1-IODOALKANES - THE EFFECT OF REACTION CONDITIONS AND RING SIZE ON THE SYNTHESIS OF 2-(PERFLUOROALKYL)ETHANOLS AND THE MECHANISM OF REACTION

The perfluoroalkylated long chain alcohol and their derivatives exhibit strong surface activity in solution and novel surface modification properties as adsorbed layers or films. A new, little known synthesis of 2-(perfluoroalkyl)ethanols (R(F)CH(2)CH(2)OH) employs a lactam, e.g., 2-pyrrolidinone (2), with an iodoalkane, e.g., C6F13CH2CH2I (1) Alkylation of 2 by heating with 1 gives C6F13CH2CH2OH (3) in 83% distilled yield, and treating the residual lactim ether salt (6 HI) with K2CO3 gives additional 3, up to 94% yield. Rate of alcohol formation (k(alc)) is unaffected by molar ratio of 2:1, yet rate of 1 reaction (k(iodo)) increases 2.44 times with doubling of 2:1 and side product C6F13CH=CH2 (4) decreases from 4 to 2%. For homologous lactams [(CH2)(n)NHC=O] (n = 3-5), selectivities (mel 3:4) are as follows: 5-membered ring, 18.4; 6-membered ring, 0.73; 7-membered ring, 0.13. Conversions to 3 are as follows: 6-membered ring, 19.4%; and 7-membered ring, 1.75%, Table 13. A three-step mechanism is proposed: (1) O-alkylation of the lactam by 1 gives lactim salt I; (2) N-substitution of salt I by another molecule of lactam forms a tetrahedral adduct (II); (3) breakdown of salt II gives 3 and iminolactam salt III. In model experiments, heating of 2 and lactim 6 yields 99% of 3 and iminolactam 5 and 1% of 4. By contrast, 7-membered 14 with 2 gives 45% of 3 and iminolactam 12, besides 4 and epsilon-caprolactam 10 (20%). For higher lactams, two competitive reactions can be discerned: (1) the S(N)2 displacement of alcohol by N-attack on salt II and a unimolecular, concerted fragmentation of the lactim, to lactam and alkene.