“Single tail” and “twin tail” 3-(perfluoroalkylethanethia)alkylsuccinic anhydrides give RF segmented diacids, amic acids, imides, esters, and salts: Unusual 1H NMR of the succinamic acids

Free radical addition of RFCH2CH2SH (1; RF = n-C6F13; n-C8F17; n-C10F21; RSH) to 2-alken-1-ylsuccinic anhydrides (2–7; C3–C6, and C8) gives adducts 8–13 (RSCHR1CH2CHR2[CHCO(O)COCH2]) in 90–100% conversion and yield. Thus, addition of thiol 1 to 2 (R1, R2 = H), or 3 (but-3-en-2-yl anhydride; R1 = H, R2 = Me), gives only terminal RS-substituted adducts 8 and 9 (respectively). However, the higher alkenyl anhydrides 4–7 (R1 = CH3(CH2)n, n=0–4) add 1 to give regioisomeric anhydrides 10a,b–13a,b with twin RF and alkyl tails of different sizes. Anhydrides 8–13a,b react quantitatively with nucleophiles. Amines give succinamic acids, and then imides; water and strong bases give diacids and salts; and, ethanol and diethylene glycol give half esters. Diethylamine and 8 give RS-substituted succinamic acid RS(CH2)3[CH(CO2H)CH2CONEt2] (24a,b). The NEt2 groups of 24a,b rotate slowly around the mesomeric CN sp2 bond of (−)OCN(+)Et2, and the two ethyl groups are non-equivalent in NMR spectra. Similarly, in succinamic acids 31a,b and 32a,b, derived from anhydride 3 and amine CH3NHR, the syn and anti methyls of the (−)OCN(+)(CH3)R amide function give two NMR signals. Likewise, the slowly rotating R[R(CH2)3N(CH3)2] groups of 31a,b and 32a,b give rise to syn and anti tautomers with non-equivalent N(CH3)2 groups. The imides from reaction of 3–7, or 8–13, with NH2(CH2)3N(CH3)2 are strongly basic and form water soluble salts with acids. These anionic, cationic, non-ionic or amphoteric RF-surfactants afford surface tensions in water below 18 dyn/cm and are similar to RF-surfactants used for fighting hydrocarbon fuel fires. The new RF-segmented compounds are analogous to RF–RH segmented amphiphiles that readily self-assemble into stable fluorinated vesicles, tubules and other organized molecular systems.