New succinamic acids, -γ-lactones, and -succinimides from (3-perfluoroalkyl-2-iodoalkyl)succinic acid anhydrides and amines: Highly surface active amphiphiles

The (3-perfluoroalkyl-2-iodoalkyl)succinic anhydrides (4 and 5) react with primary (RNH2) and secondary amines (RYNH) to yield (3-F-alkyl-2-iodoalkyl)succinamic acids. A second mole of RYNH gives the conjugate bases, 7a and 7b, as two position isomers. Only the C-1 isomer 7a can cyclize to a γ-lactone, while the carboxylate ion intramolecularly displaces iodide ion from CHI as RYNH2+I−. Simultaneously, the nucleophilic carboxylate at C-4 in the unreacted isomer 7b attacks the CONHYR group at C-1 to displace the amine and revert to the anhydride 4. Then Step (1) is repeated until all of 7a and 7b are consumed. Though a weak base, COO− is an effective nucleophile in the coiled conformation of 7a or 7b. In the next step, the CH2(CO)NHR group of the γ-lactone, with an N-attack at the carbonyl rearranges to an N-alkyl (3-F-alkyl-2-hydroxypropyl)succinimide. As above, the lactone opens its ring under stereoelectronic control (with proper alignment of lone pairs on the two O atoms) and forms a new succinimide ring. These reactions occur, successively, in an aprotic, low polarity solvent under mild conditions. Elimination of HI from 4 or 5, or the iodopropylsuccinamic acid, does not occur. Diamines, e.g. (CH3)2N(CH2)3NH2 (23) or (CH3)2N(CH2)3NH(CH3) (27), reacting with 1 mol of 4 or 5, yield the zwitterionic salt., which inter alia, cyclizes smoothly to the γ-lactone HI salt. The lactone.HI salt from 23, as above, rearranges to the N-(dimethylammonium)propyl (3-F-alkyl-2-hydroxypropyl)succinimide iodide, while the lactone salt 33HI from diamine 27, like that from diethylamine, does not rearrange. Diamine 23, reacting with the t-butyl half ester, RFCH2CHICH2CH(CO2H)CH2CO2C(CH3)3, displaces t-butyl alcohol to yield the zwitterionic salt and γ-lactone HI salt, but not the succinimide. Radical addition of RFI to N-butyl prop-2-enylsuccinimide (100 °C; no solvent) provides the desired adduct in high yield. By contrast, N-(3-dimethylamino)propyl (3-F-alkyl-2-iodopropyl)succinimide (25), loses HI intramolecularly to the basic (CH3)2N group; the concentration of 25 is 10 times greater than amines in reactions above. The RF-surfactants (nonionic, zwitterionic, anionic, and cationic salts) of this work have an oriented F-alkyl segmented tail and a fairly complex polar head; and as a group, they lower the surface tension (γa) of water to 15–17 mN m−1 at 1.5–1.7 mM concentration.