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The variation of the strength of complex formation of small polyols with cations has been examined along the series of lanthanides. The strength depends on the ionic size of the cation and on the shape and flexibility of the complexing molecule. In many cases a maximum is found around the middle of the lanthanide series. Some compounds which do not form complexes with cations separate satisfactorily on cation-exchange resin columns. More frequent use of such columns is advocated. Keywords. Lanthanide cations; complexes; ligand-exchange chromatography.

On heating aldohexoses in dimethylformamide solution with toluene-p- sulfonic acid, and removing the water formed azeotropically, the 1,6- anhydrofuranoses are formed as main products, rather than the more stable 1,6-anhydropyranoses.

Methylthiomethyl ethers are obtained in good yield from primary, secondary and tertiary alcohols by treating them with a mixture of dimethyl sulfoxide, acetic anhydride and acetic acid. The methyl- thiomethyl groups are readily removed on heating the compounds with methyl iodide in moist acetone. The methylthiomethyl ethers are converted into methyl ethers by the action of ?nickel boride?.

All the methyl glycosides of the sugars mentioned in the title were synthesized by Fischer glycosidation in the absence or in the presence of calcium chloride; addition of the salt improved the yield of some of the furanosides. The glycosides were separated on a cation-exchange resin in its calcium form. The anomeric equilibria of methyl furanosides are discussed.

By the use of complexing with calcium or strontium ions to alter the anomeric equilibria, the following methyl glycosides have been synthesized in good yield: methyl α-D-ribofuranoside, β-D-lyxo- furanoside and -pyranoside, α- and β-D-mannofuranoside, α-D- talopyranoside, α- and β-D-talo-furanoside, α-L-gulo-furanoside and- pyranoside, and all the four methyl glycosides of D-glycero-D-gulo- heptose.

Cyclitols which contain an axial-equatorial-axial sequence of three hydroxyl groups form complexes with cations. Complex formation can be detected by the downfield shifts of the signals in their p.m.r. spectra; the signal of the hydrogen atom attached to the central carbon atom of the ax-eq-ax sequence shifts to the greatest extent. Equilibrium constants of complex formation have been determined by measuring the calcium ion concentration with an ion-selective electrode. cis-Inositol appears to form some 2 : 1 complex in addition to the prevalent 1 : 1 complex. Complexes of epi-inositol with calcium and strontium chloride have been isolated.

Complex formation of alditols with metal ions in aqueous solution has been investigated by electrophoresis and by the study of the N.M.R. spectra in the presence of europium ions. Complexing occurs at three consecutive oxygen atoms which are in a gauche-gauche arrangement; the energy required to form this arrangement (by rotation around carbon-carbon bonds) determines the extent of complex formation. It appears that the alditols in aqueous solution are essentially in the same conformations as are their acetates in chloroform solution.

Several C-methyl-, deoxy-C-methyl-, C-hydroxymethyl- and C-methoxymethyl-inositols have been synthesized. The equilibrium constants for the formation of tridentate borate esters and the electrophoretic mobilities in borate solution have been determined. They were found to be in accordance with the values expected from conformational considerations, except for the C-hydroxymethyl derivatives which form complexes other than tridentate ones. The structures of the complexes were determined by n.m.r, spectroscopy.

Complex formation of muellitol with dipositive cations is fast, with tripositive cations slow, on the n.m.r . time-scale. The lanthanide- induced shifts of the signals in the 1H and 13C n.m.r . spectra of these complexes vary greatly, in sign and magnitude, with the nature of the solvent.

The 13C n.m.r. spectra of nine heptoses and of all of the heptuloses were recorded and most of the signals were assigned. From these spectra, the equilibrium compositions of the heptoses and heptuloses were determined in aqueous solution. Those of the heptoses differ, with one exception, little from those of the homomorphous hexoses but some heptuloses occur wholly in the α-pyranose form, and others are predominantly in furanose forms.

Contrary to earlier reports on closely related compounds, the reaction of all four diastereomers of 5α-cholestane-2,3-diol bismethanesulfonate with sodium iodide gives 5α-cholest-2-ene. The rate of the reaction decreases in the order 2α,3α > 2α 3β 28,3α ≈ 2β,3β. The reactions of the 5α-cholestan-2- and -3-yl methanesulfonates with sodium iodide were also investigated. The relative reaction rates are explained by considering the steric effects of the substituents.

Paper electrophoresis in an electrolyte containing calcium ions is a method suitable for the separation and characterization of many polyhydroxy compounds. The method is based on the formation ofcomplexes between the cation and at least two hydroxyl groups of the compounds. Electrophoretic mobilities are listed for many sugars, methyl glycosides and cyclitols. The mobilities convey someinformation on the structure of the compounds. The correlation of electrophoretic mobilities with the configuration and conformation of the compounds is discussed.

All the resonances have been assigned in the 13C N.M.R. spectra of the hexuloses and some of their derivatives by the use of specifically deuterated compounds and comparison with related compounds. The composition of the hexuloses at equilibrium in aqueous solution has been determined and is discussed in terms of conformational analysis. The synthesis of D-fructose[l-D], D-fructose[3-D] and D-fructose[4-D] is described.

The equilibrium compositions of 1-deoxy-D-fructose, 1-deoxy-L-sorbose, 1-deoxy-L-psicose, D-threopentulose, D-arabino- and L-xylo-3-hexulose and coriose in aqueous solution have been determined by 13C N.M.R. spectroscopy. In all but the last case, considerable amounts of the acyclic keto form are present at equilibrium. The hydrated keto form was not detected; a model compound, l-deoxy- 3,4,5,6-tetra-O-methyl-D-fructose, was found not to be hydrated in aqueous solution.

Addition of lanthanide ions to aqueous solutions of some methyl glycosides and 1,6-anhydrohexoses causes shifts of the signals in their p.m.r. spectra. The approximate location of the cation in the complexes was determined and an attempt was made to explain the shifts in terms of contact and pseudocontact interactions.

Addition of lanthanide ions to epi-inositol and related compounds in aqueous solution causes shifts in their p.m.r. spectra which are interpreted as being due to diamagnetic, pseudocontact, and contactinteractions. The contact interactions show stereospecificity: they are greatest when the bonds connecting the protons to the cation form a planar zig-zag arrangement.

Pinpollitol, a new cyclitol recently isolated from Pinus radiata, has been synthesized and its structure proven to be 1,4-di-O-methyl-D-chiro-inositol.

The mobilities of numerous polyols, sugars and methyl glycosides on ion-exchange resin thin-layer plates in the calcium and lanthanum form have been measured. Under these conditions, alditols which have a threo-threo sequence of hydroxy groups complex more strongly with lanthanum than with calcium, whereas methyl glycosides complex less strongly.

The shifts induced in the 13C n.m.r . spectrum of epi-inositol by the addition of various lanthanide ions have been determined and have been analysed in terms of contact and pseudocontact interactions. The behaviour of the three heavy lanthanides was found to be anomalous, probably owing to their smaller ionic radii and their lesser extent of hydration. Similar measurements have also been carried out on four 1,6- anhydro-β-D-hexopyranoses.

The originally postulated configurations of camphane-2-endo,3-exo- and -2-exo,3-endo-diols, which were recently claimed to be incorrect, have been confirmed by the use of 13C n.m.r. spectroscopy and by the X-ray crystal structure analysis of the dibenzoate of camphane-2-endo,3-exo-diol.

The compounds mentioned in the title were synthesized from 2,5-anhydro- D-glucitol. 2,5-Anhydrogalactitolforms complexes with cations involving the two hydroxyl groups in the ring and the ring-oxygen atom; 2,5-anhydroallitol does not form such complexes. The reaction of cis-(2,5- dihydrofuran-2,5-diyl)dimethyl dibenzoate (5) with iodine and silver acetate was found to be unusual, hydroxylation occurring from the unhindered side.

In the syrupy state, DL-glyceraldehyde, D-erythrose and D-threose consist mainly of mixtures of dimeric forms. Their aqueous solutions also contain some dimers; glyceraldehyde is present mainly as the aldehydrol, and the tetroses as mixtures of the furanoses and the aldehydrol. All the solutions contain some (> 1 %) of the aldehydo form. The proportion of the monomeric forms has been determined, from the 1H n.m.r. spectra, at various temperatures.

The tautomeric equilibrium of D-allose in aqueous solution is altered by the presence of some cations which form complexes with the α-pyranose and the α-furanose but not with the β-pyranose and the β-furanose forms. Determination of the proportions of the tautomeric forms by N.M.R. allows a comparison of the complexing ability of cations. Lanthanum, calcium, and strontium form the strongest complexes. The behaviour of D-lyxose, D-ribose, and D-glycero-D-gulo-heptose on complexing is described.

The proportion of the pyranose and furanose forms in aqueous solutions of deoxyaldoses has been determined by p.m.r. spectroscopy. Removal of a hydroxyl group from C2 or C3 of an aldose causes an increase in the furanose content, particularly if the group was cis to another group. The strongest unfavourable interaction in the furanose ring appears to be the one between the side-chain and a neighbouring cis hydroxyl group.

Addition of acetic anhydride to the reagent, chromium trioxide in acetic acid, changes the outcome of the oxidation of cyclic methylene acetals, giving cyclic carbonates in addition to formyl ketones. Five-membered acetals (acetylated 3,4-O-methylene-D-mannitol and-L-iditol) give good yields of the carbonates, which are readily isolated as diisopropylidene derivatives. Six-and seven-membered acetals (acetylated 2,4-O-methylene-D-glucitol and 2,5-O-methylene-D-mannitol) give poor yields of carbonates, which are unstable under the acid conditions used for deacetylation: the carbonate group migrates or is removed.

The D-arabino, L-lyxo, and L-xylo isomers of 3-hexulose have been synthesized by oxidation, with chromium trioxide in acetic acid, of fully acetylated derivatives of 3,4-0-ethylidene-D-mannitol, 3,4-0-ethylidene-L-iditol, and 2,4-O-benzylidene-D-glucitol, respectively. The D-ribo isomer has been obtained from the L-lyxo compound by inversion at C5. The 3-hexuloses were characterized as their crystalline di-O-isopropylidene derivatives: the arabino- and ribo-hexuloses each give three diacetals. The stereochemistry of these derivatives, and of the spiro-acetals of ketoses in general, is discussed.

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Oxidation of fully acylated methylene and benzylidene acetals of alditols with chromium trioxide in acetic acid yields fully acylated ketoses in their keto form. Derivatives of hex-3-uloses have been prepared by this method. Syntheses of 3,4-O-methylene-D-mannitol and 3,4-O-methylene-D-glucitol are described.

The stereochemistry of tritiation of crystalline (-)-inositol and its liquid hexa-O-methyl derivative by the Wilzbach labelling procedure has been investigated. Predominance of configurational retention was found to accompany substitution in the crystalline compound, whereas configurational inversion predominated during substitution in the liquid.

Evidence, obtained mainly by determining the amount of intermediary esters formed during the oxidation of aldoses by periodate, indicates that aldoses are pre- dominantly attacked in their original cyclic form ; that the oxidation of the intermediary aldoses is faster than their cyclization ; and that the oxidation of the intermediary hemiacetals is faster than their hydrolysis. Inositols are oxidized to tartron-aldehyde which undergoes " overoxidation " ; 0-methylinositols are degraded to methyl glyoxylate.

The hypothesis is advanced that the reaction of sulphonyl halides with amino-derivatives of nitrogen-containing cyclic compounds occurs on the ring-nitrogen (which is the more basic), followed either by reaction of the amino-group with another molecule of sulphonyl halide, or by migration of the sulphonyl group from the ring to the ammo-nitrogen. Several apparently anomalous cases of this reaction are explained.

Various disulphonyl derivatives of 2-aminopyridine and 2-aminothiazole are described. It is proved that the two sulphonyl groups are on two different nitrogens ; a similar conclusion is reached for dibenzoyl-2-an~inopyridme. Several of the disulphonyl compounds exist in two forms which are regarded as geometrical isomers.