Molecular structures of 3-[(2,2,3,3-tetrafluoropropoxy)methyl]- and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyridinium saccharinates

Abstract

The salts 3-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium saccharinate, CHFNO·CHNOS, (1), and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyridinium saccharinate, CHFNO·CHNOS, (2), i.e. saccharinate (or 1,1-dioxo-1λ,2-benzothiazol-3-olate) salts of pyridinium with -CHOCHCFCFH and -CHOCHCFCF meta substituents, respectively, were investigated crystallographically in order to compare their fluorine-related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven-membered ring reveals a double hydrogen-bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation-anion π-interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2).

Food Sweetener Saccharin in Binary Organocatalyst for Bulk Ring‐Opening Polymerization of Lactide

“…Saccharin, the acidic part in our cocatalyst, has been used as an artificial sweetener since 1900 and certified rigorously safe in food additives. The adduct DMAP · Sac was stabilized by intermolecular double H-bonds in the solid, [35] however, we proposed that in solution of DMAP · Sac in monomer(s) at elevated temperatures, weaker one of the two H-bonds was dissociated into a bifurcate conformation (Scheme 2, c) in which a negatively charged enolate was capable of activating the initiator (In) and a positively charged pyridinium was capable of activating the monomer (M). [34] DMAP was FULL PAPER asc.wiley-vch.de a strong enough base that will abstract a proton from enolate saccharin to form a pyridinium saccharinate adduct DMAP · Sac (Scheme 2, b).…”

“…[34] DMAP was 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 a strong enough base that will abstract a proton from enolate saccharin to form a pyridinium saccharinate adduct DMAP · Sac (Scheme 2, b). The adduct DMAP · Sac was stabilized by intermolecular double H-bonds in the solid, [35] however, we proposed that in solution of DMAP · Sac in monomer(s) at elevated temperatures, weaker one of the two H-bonds was dissociated into a bifurcate conformation (Scheme 2, c) in which a negatively charged enolate was capable of activating the initiator (In) and a positively charged pyridinium was capable of activating the monomer (M). Our assumption was that DMAP and saccharin binary catalyst (DMAP · Sac) in its pyridinium saccharinate form would be a promising bifunctional catalyst in ring-opening polymerizations of cyclic esters (Scheme 3) including lactide, lactones, and cyclic carbonates.…”