Himic Anhydride: A Retro Diels–Alder Reaction for the Organic Laboratory and an Accompanying NMR Study

Abstract

The thermal equilibration of himic anhydride [IUPAC (2- endo ,3- endo )-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride] to (2- exo ,3- exo )-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid anhydride and subsequent recrystallization of the exo -product can be performed as a standard undergraduate laboratory experiment requiring minimal equipment. The interpretation of the 1 H NMR spectra for these norbornene carboxylic anhydride molecules promotes an appreciation of constrained ring systems and factors that affect chemical shifts and coupling constants.

Polynorbornene-based bioconjugates by aqueous grafting-from ring-opening metathesis polymerization reduce protein immunogenicity

“…exo-NBDA, 64 NB-PEG, 53 NB-Zwit, 53 and oNB-PEG 44 were synthesized as previously described. All other reagents and solvents were used as obtained from commercial sources.…”

Updating Dimedone─The Humble Hero of the Organic Laboratory

“…Students will therefore gain a better appreciation that when considering solvation properties, a number of factors need to be considered, including dipole–dipole interactions, hydrogen-bonding interactions (if present), and thermodynamic parameters such as overall entropy and enthalpy. For dimedone, the ratio of tautomers in equilibrium in solution can be determined by 1 H NMR spectroscopy comparing respective integration values, provided that both tautomers are visible in appreciable quantities, as they are in CDCl 3, and this analysis offers a good example of laboratory classes reinforcing NMR interpretations. − IR spectra will similarly show the absence or presence of a hydroxyl stretch depending on the method of acquiring the spectrum.…”

Tricyclononenes and tricyclononadienes as efficient monomers for controlled ROMP: understanding structure–propagation rate relationships and enabling facile post-polymerization modification

“…TCNs and TCNDs are tricyclic, strained olens with fused cyclobutane and cyclobutene rings, respectively, connected to the two exo positions of the NB skeleton. Compared to other exo-substituted NB monomers, which oen require high temperatures [9][10][11] and/or precious metal catalysts 8,12 for their synthesis, exo-TCNs and TCNDs can be conveniently assembled by thermal cycloadditions of activated olens and quadricyclane with perfect exo selectivity. 13,14 While TCN and TCNDbased polymers have been synthesized using Mo (Schrock-type initiators) 15 and Ru (Grubbs 1st and 2nd generation initiators) initiated ROMP 16,17 and studied for applications in gas separations, [18][19][20][21][22][23][24][25] no studies of their performance under "living" ROMP conditions initiated by G3 or post-polymerization functionalization have been reported.…”