Syntheses of 6N(N′-formyl-D-phenylalanyl)-deoxyamino-β-cyclodextrin and 6N(N′-formyl-L-phenylalanyl)deoxyamino-β-cyclodextrin and their inclusion behavior

6N(N-formyl-D-phenylalanyl)-deoxyamino--cyclodextrin and 6N(N-formyl-L-phenylal-anyl)-deoxyamino--cyclodextrin (I andII) were prepared. These new hosts formed intramolecular host-guest complexes and included naphthyl derivatives preferentially with a stoichiometry of 1:1. The inclusion behavior was different between I and II because the cavity shape formed with the CD cavity and the phenylalanine moiety of I was different from that of II.     

Doubly bridged biscalix[4]arene for homotropic and heterotropic allosteric effects on ion recognition

A novel host, which shows homotropic and heterotropic allostery for Na⁺ and Ag⁺ recognition, is constructed by utilizing a biscalix[4]arene skeleton bearing bipyridine and ester moieties. The host binds two Na⁺ ions, but the second binding to Na⁺ is considerably suppressed by the first Na⁺ ion bound in the other binding site.     

Steric structure of isomeric bis-2,2-dichlorocyclopropyl ethers

Conclusions The meso- and dl-bis-2,2-dichlorocyclopropyl ethers exist in solution in a gauche-gauche type of conformation, with the three-membered rings arranged along different sides of the C-O-C plane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2828–2831, December, 1978.     

Reactions of α-HALO-α,β-unsaturated aldehydes with second amines —novel method for the preparation of N-disubstituted α-aminocrotonaldehydes

Conclusions -Halocrotonaldehydes react with secondary amines to give N-disubstituted -aminocrotonaldehyde derivatives, N,N-tetrasubstituted 1,2-diaminoethenes, and N-formyl derivatives of the amine starting materials.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1801–1805, August, 1987.     

Polymerization of propiolaldehyde. IV. Synthesis of a functional polymer having an ethynyl group

The cationic homopolymerization and copolymerization of propiolaldehyde were carried out with use of boron trifluoride etherate as an initiator at the temperatures of 0 to ?78°C. Poly(ethynyl)oxymethylene was prepared by the homopolymerization at ?78°C, but it was readily depolymerized to the monomer. The cationic copolymerization with styrene at ?78°C proceeded almost exclusively through the aldehyde addition and a new functional copolymer was obtained. With a rise in polymerization temperature, the ethynyl addition was mixed slightly.     

ATP and AMP formation from ADP in the presence of cyclodextrin

A new nonenzymatic formation of ATP from ADP was observed in the presence of cyclodextrin in a phosphate buffer of pH 7.00 at 37.0°C under at mospheric conditions. Time conversion curves were obtained in the presence of -cyclodextrin and heptakis-(2,6-dimethyl)--cyclodextrin. The effect of adding -cyclodextrin, MgCl₂, phosphate buffer and creatine was examined kinetically as well as the effect of cyclohexanol as an inhibtor.     

Leaving group effects in gas-phase substitutions and eliminations

Using a methodology recently developed for studying the product distributions of gas-phase S(N)2 and E2 reactions, the effect of the leaving group on the reaction rate and branching ratio was investigated. Using a dianion as the nucleophile, reactions with a series of alkyl bromides, iodides, and trifluoroacetates were examined. The alkyl groups in the study are ethyl, n-propyl, n-butyl, isobutyl, isopropyl, sec-butyl, and tert-butyl. The data indicate that leaving group abilities are directly related to the exothermicities of the reaction processes in both the gas phase and the condensed phase. Gas-phase data give a reactivity order of iodide > trifluoroacetate > bromide for S(N)2 and E2 reactions. Previous condensed phase data indicate a reactivity order of iodide > bromide > trifluoroacetate for substitution reactions; however, the basicities of bromide and trifluoroacetate are reversed in the condensed phase so this reactivity pattern does reflect the relative reaction exothermicities. Aside from this variation, the gas-phase data parallel condensed phase data indicating that the substituent effects are rooted in the nature of the alkyl substrate rather than in differences in solvation. The experimental data are supported by calculations at the MP2/6-311+G(d,p)//MP2/6-31+(d) level.     

Oxidation of Two α-Hydroxy Acids by Vanadium(V)

Summary. The pathways for the oxidation of tartaric acid and citric acid by vanadium(V) in perchloric acid medium have been studied at 303K by following the formation of vanadium(IV) spectrophotometrically at 760nm. The oxidation reaction displays fractional order dependence with respect to both the -hydroxy acids concentrations as well as fractional (tartaric acid) and first order (citric acid) dependencies with respect to the perchloric acid concentration. It does not matter at all whether the ionic strength was varied or was maintained constant. The reaction rate remains essentially constant with increasing ionic strength in the tartaric acid oxidation, but decreases slightly in the citric acid case. A decrease of the dielectric constant of the reaction medium results in a rate decrease in the tartaric acid oxidation and in a rate enhancement in the citric acid reaction. The activation parameters were obtained from studies of the reactions at different temperatures (293 to 313K). Based on the experimentally determined rate laws oxidation mechanisms and theoretical rate laws were proposed.Received April 8, 2003; accepted May 10, 2003 Published online September 18, 2003     

Adsorption and Recovery of Ionic Surfactants by β-Cyclodextrin Polymer

The adsorption and recovery of ionic surfactants, such as dodecylbenzenesulfonic acid (DBS) and benzalkonium chloride (BKC), from an aqueous solution were studied using the β-cyclodextrin polymer (β-CDP). BKC always demonstrated a higher adsorption efficiency than DBS in batch tests, isotherms, and column tests. The adsorption characteristics of the surfactants seemed to be caused by inclusion into β-CD, and they were easily determined using the Langmuir adsorption isotherm. Furthermore, the surfactants adsorbed by β-CDP were easily released by shaking it with a mixture of water and methanol. Recovery efficiency was dependent on the mixture ratio of the solvent, and regenerated β-CDP was reusable as an adsorbent.