84227-47-4

A procedure has been proposed for the synthesis of monoazacrown ethers by reaction of N-benzyldiethanolamine with oligo(ethylene glycol) bis-p-toluenesulfonates in a two-phase system aromatic hydrocarbon-50% aqueous alkali, followed by removal of the benzyl group by catalytic hydrogenolysis. The maximal yields of N-benzylaza-12-crown-4, -18-crown-6, and -21-crown-7 were achieved by adding 4-10 equiv of LiCl, BaBr2, and CsCl, respectively, to the reaction mixture, which probably indicated template effect. Pleiades Publishing, Ltd., 2012.

The alkali metal and ammonium cation binding properties of N-pivot, 12-crown-4 lariat ethers are recorded here.A reinvestigation of N-pivot lariat ethers having (CH2CH2O)nCH3 side arms is presented, and data are reported for fresh samples of these long chain compounds.Details of the X-ray crystal structures obtained for N-aza-12-crown-4 are reported.The complex crystallizes in the tricyclic space group P1 with cell constants a = 8.712 (2) Angstroem, b = 8.694 (3) Angstroem, c = 11.740 (3) Angstroem, α = 111.44 (2) deg, β = 90.76 (2) deg, γ = 103.50 (2) deg, and Z = 2 for Dc = 1.591 gcm-1.Least-squares refinement based on 3723 observed reflections led to a final conventional R value of 0.052.All of the lariat ether donors bind to the alkali metal cation, with the macroring in the crown conformation.The 12-crown-4 system behaves, in many ways, like the 15- and 18-membered ring analogues.The presence of an octakis(ethyleneoxy) side arm does not diminish cation binding strength in this series as reported for the 15- and 18-membered ring compounds.Indeed, the fall off in binding constants previously reported for the longest chain examples of the latter families now appears to be due to sample decomposition rather than solvent encumbrance.

Aza-12-crown-4 forms a 2:1 sandwich complex similar to that known for 12-crown-4 sodium iodide, except that the presence of >NH in each ring makes Na-donor bonds unequal in strength and leads to hydrogen bonding with the counterion.The heteroatoms of each macroring are coplanar, and both nitrogens are on the same side of the complex (twist angle 43 deg from eclipsed).This may be due to a long (and weak) hydrogen bond to iodide, an interaction confirmed by analysis using Raman spectroscopy.The previously unreported 1:1 and 2:1 cation affinity constants (anhydrous MeOH , 25 deg C) for this macrocycle are logKS(1:1) = 1.3 +/- 0.1 and logKS(2:1) = 2.0 +/- 0.1, respectively.

Eleven lipophilic bis(monoaza crown ether) derivatives were synthesized, in which two monoaza crown ethers with 9-, 12-, 15-, or 18-membered rings are linked through the nitrogen atoms by an alkane-, diether-, or diester-type bridge chain bearing a dodecyl group.Sodium and potassium binding with the bis(monoaza crown ether) was determined potentiometrically and compared with those for previous bis(crown ethers) 5 (n = 1 - 3) and corresponding monocyclic analogues 4 and 6 (n = 1 - 3).Marked bis(crown ether) effect was observed only for the alkane-type bis(monoaza-12-crown-4) and bis(monoaza-15-crown-5) derivatives 1 (n = 1,2) on complexing Na+ and K+, respectively.It was suggested that in some of the other bis(monoaza crown ethers) lariat-ether effect works instead.Bis(monoaza-9-crown-3) derivatives 1 and 2 (n = 0) possess very poor cation-complexing ability.Acidity constant values gave some hints about the bis(crown ether) effect.

The efficient synthesis of several 12-membered ring, N-pivot lariat ethers are reported and it is shown that binding to sodium cations is weak except when an oligoethyleneoxy sidearm is long enough to provide additional solvation.

Primary amines condense with 1,11-diiodo-3,6,9-trioxaundecane in acetonitrile solution containing dispersed Na2CO3 to give N-substituted derivatives of monoaza-12-crown-4, including several directly appended with an additional donor group.The unsubstituted azacrown and the N-methyl derivative were obtained from the N-benzyl derivative.The alkali cation complexing properties were studied by 13C NMR spectroscopy.It was found that the presence of an additional donor atom in the side-chain suppresses the formation of 2:1 in favour of 1:1 complexes.

Two molecules of monoaza-12-crown-4 can be linked through nitrogen in one step by direct double alkylation; the resulting bis-crown aminoethers give intramolecular alkali cation sandwich complexes which are particularly strong when the bridge is -CH2CH2- and the cation is sodium.