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Some Implications Of Chu's 10Ψ10 Generalization Of Bailey's 6Ψ6 Summation Formula, James Mclaughlin, Andrew Sills, Peter Zimmer

Mathematical Sciences: Faculty Publications

Lucy Slater used Bailey's 6ψ6 summation formula to derive the Bailey pairs she used to construct her famous list of 130 identities of the Rogers-Ramanujan type.

In the present paper we apply the same techniques to Chu's 10ψ10 generalization of Bailey's formula to produce quite general Bailey pairs. Slater's Bailey pairs are then recovered as special limiting cases of these more general pairs.

In re-examining Slater's work, we find that her Bailey pairs are, for the most part, special cases of more general Bailey pairs containing one or more free parameters. Further, we also find new …

Rademacher-Type Formulas For Partitions And Overpartitions, Andrew Sills

Mathematical Sciences: Faculty Publications

A Rademacher-type convergent series formula which generalizes the Hardy-Ramanujan-Rademacher formula for the number of partitions of n and the Zuckerman formula for the Fourier coefficients of ϑ4_0 | τ_−1 is presented.

Multichannel Spectrophotometry For Analysis Of Organophosphate Paraoxon In Beverages, Miroslav Pohanka, Jana Zdarova Karasova, Kamil Kuca, Jiri Pikula

Turkish Journal of Chemistry

Multichannel spectrophotometry was performed to assay for paraoxon in spiked beverages. A 96-well microplate was used for this purpose. The measuring protocol was based on inhibition of the enzyme acetylcholinesterase by paraoxon that resulted in decreased or no reaction of the enzyme product thiocholine with Ellman's reagent (5,5'-dithiobis [2-nitrobenzoic acid]). The above assay was practically tested using spiked drinking water, mineral water, and coffee. Analytical parameters such as the limit of detection, time, and sample size consumption were adequate. The limit of detection for beverages ranged from 32 to 48 ppb corresponding to 0.32-0.48 ng of paraoxon in absolute values. …

Influence Of Alcl_3 On The Optical Properties Of New Synthesized 3-Armed Poly(Methyl Methacrylate) Films, Adnan Kurt

Turkish Journal of Chemistry

Three-armed poly(methyl methacrylate)[PMMA] was synthesized by atom transfer radical polymerization at 100 °C using benzene-1,3,5-triyl tris(4-(bromomethyl) benzoate as 3-armed initiator and a cuprous(I) bromide/2,2'-bipyridine catalytic system. The characterization of PMMA was confirmed by FT-IR, ^1H-NMR, GPC, DSC, and TGA techniques. Optical absorption measurements were also studied by UV-VIS technique. Transmittance and reflectance measured in the wavelength range 300-700 nm were used to calculate the optical constants. The changes in dispersion and Urbach parameters were investigated as a function of AlCl_3 content. The wide band tails increased in width and the optical energy gap decreased from 2.39 to 1.28 eV as …

Template Synthesis And Characterization Of 16-Membered Octaazamacrocyclic Complexes: A Photoelectron Spectroscopic Study, Abul Kalam, Vishnu Tripathi, Shekhar Srivastava, Yogesh Pandey, Anil Kumar, Alok Gupta, Sharat Srivastava, Ankoor Purohit

Turkish Journal of Chemistry

A novel series of complexes of the type [MLX_2] where M= Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); X= C^- or NO_3^- were synthesized by template condensation of hydrazine hydrate, acetaldehyde, 2,4-pentanedione, and thiocarbohydrazide in the presence of divalent metal salt in methanolic solution. The complexes were characterized with the help of elemental analysis, conductance measurements, magnetic measurements, electronic, NMR, XPS, and infrared and far infrared spectral studies. Electronic spectra along with magnetic moments suggest 6-coordinated octahedral geometry for these complexes. The low value of molar conductance indicates them to be non-electrolytes.

Synthesis And Uranyl Ion Adsorption Study Of Cross-Linked Allyl Propionate-Maleic Anhydride-Styrene Terpolymer, Elchin Akperov, Abel Maharramov, Oktay Akperov

Turkish Journal of Chemistry

Allyl propionate-maleic anhydride-styren terpolymer has been modified with glycerin in order to prepare a new cross-linked functional polymer sorbent. The synthesized cross-linked polymer sorbent has a network structure and contains carboxylic acid, carbonyl, hydroxy, and ester groups, all of which are capable ofinteracting with metal ions. The sorption behavior of UO_2^{2+} ions under optimum sorption conditions was determined. The sorption properties of the sorbent were determined under different conditions by varying of the pH of medium, the sorbent weight, and the initial concentration of uranyl ions. The maximum experimental sorption capacity of the sorbent for uranyl ions was measured as …

Isolation Of Bis(1,4-Diphenyl-1,4-Bis(2-Pyridyl)-2,3-Diaza-1,3-Butadiene) Disilver With Bridging (N-N) Dinucleating Subunits: Formation Of A 6-Membered Chelate Ring, Amitabha Datta, Neerish Revaprasadu

Turkish Journal of Chemistry

A novel Ag(I) dinuclear complex {[(C_6H_5)(C_5H_4N)-C=N-N=C- (C_5H_4N)(C_6H_5)]Ag}_2.ClO_4(ClO_4) (1/2CH_3CN) (1) that was derived under mild conditions, during the course of combination of AgClO_4 with a polymorphic azine ligand, 1,4-diphenyl-1,4-bis(2-pyridyl)-2,3- diaza-1,3-butadiene (L) (condensed product of phenyl 2-pyridyl ketone and hydrazine monohydrate) is reported. The aforementioned complex is based on a central rotationally flexible diazine subunit (N-N). The azine ligand, L, having the N_2 dinucleating fragment, provides a coordination focus for pairs of metal centres and ultimately leads to the formation of a 6-membered chelate ring in 1.

An Investigation Of Energy Transfer Between Coumarin 35 And Xanthene Derivatives In Liquid Medium, Mahmut Toprak, Mustafa Arik

Turkish Journal of Chemistry

The energy transfer between coumarin 35 (C35) and pyronin compounds, which are xanthene derivatives, i.e. pyronin B (PyB) and pyronin Y (PyY), in methanol was investigated at room temperature by using steady-state absorption, emission, and time-resolved fluorescence spectroscopy. Fluorescence energy transfer rate constants (k_T) and critical radius (R_0) were determined for C35-PyB and C35-PyY molecular pairs in methanol. The obtained values of k_T and R_0 indicated that the dipole-dipole interaction between C35-PyB and C35-PyY molecular pairs accounted for the energy transfer mechanism. The energy transfer efficiency and the distance between the donor and acceptor (r) were also calculated for donor-acceptor …

Ionic Liquids As Solvent For Efficient Esterification Of Carboxylic Acids With Alkyl Halides, Yetki̇n Gök, Bülent Alici, Engi̇n Çeti̇nkaya, İsmai̇l Özdemi̇r, Özlem Özeroğlu

Turkish Journal of Chemistry

The selective esterification of carboxylic acid derivatives with a variety of alkyl halides was carried out using ionic liquid as solvent in the presence of triethylamine. The reaction was found to proceed under relatively mild conditions with excellent conversions (up to 99%) and selectivities. The ionic liquid was recycled and reused.

Electrooxidation Of Hydrazine By Carminic Acid As A Mediator On A Glassy Carbon Electrode, Mohammad Mazloum Ardakani, Seyed Hossein Moosavizadeh, Ali Sadeghiane, Mohammad Hossein Mashhadzadeh, Mohammad Ali Karimi

Turkish Journal of Chemistry

Electrocatalytic oxidation of hydrazine on a glassy carbon electrode with carminic acid as a homogeneous mediator in 0.1 M phosphate buffer solution (pH 8.0) was studied. Cyclic voltammetry study showed that the catalytic current of the system depends on the concentration of hydrazine. The magnitude of the peak current obtained by linear sweep voltammetry for carminic acid increased sharply in the presence of hydrazine and proportional to the hydrazine concentration in the ranges of 5.0-800.0 \mu M and the detection limit was 3.0 \mu M by this technique. The detection limit was promoted by differential pulse voltammetry and decreased to …

Stabilizing Cyclacene Molecules, Muthana Shanshal

Turkish Journal of Chemistry

It is shown that introducing a single methylene group into each trannulene ring of a cyclacene molecule compels the formation of a non-bonded molecular orbital, NBMO, in the ring. The union of both trannulenes conforms to a first order perturbation change in the total energy according to Dewar's PMO theory. The NBMO coefficients can be calculated then according to Coulson's pairing theorem. The PMO calculated new HOMO-LUMO energies of the cyclacene indicate the relative stabilization of the singlet over the triplet state of the cyclacene. The results are confirmed by the DFT calculation of differently substituted bis, methylene cyclacenes. The …

An Efficient Synthesis Of Schiff Bases Containing Benzimidazole Moiety Catalyzed By Transition Metal Nitrates, Akbar Mobinikhaledi, Naser Foroughifar, Mehdi Kalhor

Turkish Journal of Chemistry

A simple and efficient method has been developed for the synthesis of some novel Schiff bases via the reaction of aromatic aldehydes with 2-aminobenzimidazole by using catalytic amount of M(NO_3)_2.xH_2O in an organic solvent at room temperature. Some advantages of this protocol are its very good yields, use of available catalysts, simple workup procedure, and short reaction times.

Synthesis, Characterization, Antibacterial And Antifungal Evaluation Of Some New Platinum(Ii) Complexes Of 2-Phenylbenzimidazole Ligands, Semra Utku, Mustafa Topal, Ayli̇n Döğen, Mehmet Sami̇ Seri̇n

Turkish Journal of Chemistry

A series of platinum(II) complexes of the type [PtL_2Cl_2] 1, [PtL_2I_2] 2, [PtL_2(oxalato)] 3, and [PtL_2(malonato)] 4 (L= 2-phenylbenzimidazole ligands as ``non-leaving groups'') were synthesized and characterized by their elemental analyses, IR, ^1H NMR, and ESI-LC/MS. The in vitro antimicrobial activity of the synthesized compounds has been evaluated by the macrodilution method against gram-positive bacteria, such as Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis; gram-negative bacteria, such as Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonia; and yeast like fungi, such as Candida glabrata and Candida parapsilosis. In general, based on the data obtained in this study, synthesized complexes 1-4 might …

Mannich Base Derivatives Of 3-Hydroxy-6- Methyl-4h-Pyran-4-One With Antimicrobial Activity, Demet Us, Barkin Berk, Eni̇se Ece Gürdal, Ni̇han Ayteki̇n, Zühtü Tanil Kocagöz, Berrak Çağlayan, Işil Kurnaz, Di̇lek Demi̇r Erol

Turkish Journal of Chemistry

A series of 3-hydroxy-6-methyl-2-[(substitutedpiperidine-1-yl) methyl]-4H-pyran-4-one structured compounds were synthesized by reacting 5-hydroxy-2-methyl-4H-pyran-4-one with suitable piperidine derivatives using Mannich reaction conditions. Antibacterial activities of the compounds for E. coli ATCC 25922, S. paratyphi ATCC BAA-1250, S. flexneri ATCC 12022, E. gergoviae ATCC 33426, and M. smegmatis ATCC 14468 were assessed in vitro by the broth dilution method for determination of minimum inhibitory concentration (MIC). In addition, their inhibitory effects over DNA gyrase enzyme were evaluated using a DNA gyrase supercoiling assay. All the synthesized compounds showed a MIC value of either 8 or 16 \mu g/mL for M. smegmatis, whereas minimum …

Electrochemical Properties Of 1-(O-, M-, P-Nitrophenyl)-3-(M-Nitrophenyl)- 5-Phenylformazans And Their Nickel Complexes, Habi̇be Tezcan, Mehmet Levent Aksu

Turkish Journal of Chemistry

The electrochemical properties of NO_2 formazans and their Ni(II) complexes were investigated. The investigated formazans included a NO_2 group at the o-, m-, and p-positions of the 1-phenyl ring and at the m-position of the 3-phenyl ring. The oxidation and reduction peak potentials, number of electrons transferred, diffusion coefficient, heterogeneous rate constant, and possible reaction mechanism of the compounds were determined with the use of cyclic voltammetry (CV), ultramicrodisc electrodes (UMEs), and chronoamperometry (CA). The peak potentials (E}_{ox1}) were observed to shift towards more anodic potentials in formazans and more cathodic potentials in their respective Ni complexes compared to unsubstituted …

(E)-3-[(3-(Trifluoromethyl)Phenylimino)Methyl] Benzene-1,2-Diol: X-Ray And Dft Calculated Structures, Başak Koşar, Çi̇ğdem Albayrak, Mustafa Odabaşoğlu, Orhan Büyükgüngör

Turkish Journal of Chemistry

The crystal structure of (E)-3-[(3-(Trifluoromethyl)phenylimino)- methyl]benzene-1,2-diol was determined using X-ray diffraction and the molecular structure was investigated with density functional theory (DFT). The X-ray study showed that the title compound has a strong intramolecular O-H...N hydrogen bond and 3-dimensional crystal networks are primarily determined by O-H...O intermolecular hydrogen bonds and weak van der Waals interactions. The strong O-H...N bond is evidence of the preference for the phenol-imine tautomeric form in the solid state. Optimized molecular geometry was calculated with DFT at the B3LYP/6-31G(d,p) level. The results from both experiment and theoretical calculations for the title compound are compared with each …

Heterocyclic Synthesis Using Nitrilimines: Part 14. Synthesis Of New Pyrazole Derivatives, Hany Dalloul

Turkish Journal of Chemistry

A new series of 1,3,4,5-tetrasubstituted pyrazoles have been synthesized by the 1,3-dipolar cycloaddition of suitable nitrilimines to 3-propylidene and 3-benzylidene-phthalide. Both analytical and spectroscopic data of all the synthesized compounds are in full agreement with the proposed structures.

Friedel-Crafts Acylation Of Arenes With Carboxylic Acids Using Silica Gel Supported Alcl_3, Kaveh Parvanak

Turkish Journal of Chemistry

Aromatic compounds react smoothly with carboxylic acids in the presence of silica gel supported aluminium trichloride to afford the corresponding ketones with high regioselectivity in high to excellent yields. The catalyst is stable (as a bench top catalyst) and can be easily recovered and reused without appreciable change in its efficiency.

Surfactant-Controlled Aqueous Synthesis Of Sno_2 Nanoparticles Via The Hydrothermal And Conventional Heating Methods, Muhammad Akhyar Farrukh, Heng Boon Teck, Rohana Adnan

Turkish Journal of Chemistry

Tin oxide nanoplates and nanoballs were fabricated using a cationic surfactant of cetyltrimethylammonium bromide (CTABr) as an organic supramolecular template and tin(IV) chloride as an inorganic precursor via the hydrothermal and conventional heating methods. Urea, which decomposes to ammonium and hydroxide ions during hydrolysis, was used as the source of slow homogeneous precipitation of Sn^{4+} with OH^- to control the particle size. The influence of different reaction parameters (time, temperature, and ratio of Sn^{4+} to CTABr) on particle sizes, particle distribution, and morphology was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. XRD …

A Calorimetric Study Of The Interaction Of Silver Ions With Jack Bean Urease, Ali Akbar Saboury, Elahe Poorakbar, Gholamreza Rezaei-Behbehani

Turkish Journal of Chemistry

A thermodynamic study of silver ions by jack bean urease (JBU) was carried out at 2 temperatures, 27 and 37 °C, in Tris buffer (30 mM; pH 7.0) using isothermal titration calorimetry (ITC). There was a set of 12 identical and noninteracting binding sites for the silver ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding were 185 \mu M and -16.7 kJ mol^{-1} at 27 °C, and 229 \mu M and -16.3 kJ mol^{-1} at 37 °C, respectively. The molar entropy of binding was +15.7 J K^{-1} mol^{-1} at 27 °C and +17.1 J K^{-1} mol^{-1} …

A Pca Based Method For Image And Video Pose Sequencing, James Massaro

Theses

Problems exist in image sequence processing that require an ordered set of object views. In some cases, multiple angled images are acquired in random order and the angle of view information is not available. When this occurs, the poses have to be put into proper order. For example, in databases containing images of an object or scene taken over a period of time, each image pose or angled-view with respect to the camera or scene is unknown. This is important to achieve a complete or partial three-dimensional reconstruction. Other applications exist in photogrammetry, machine vision, computer-aided design, and military intelligence. …

Turbulent Mixing In A Strongly Forced Salt Wedge Estuary, David K. Ralston, W. Rockwell Geyer, James A. Lerczak, Malcolm Scully

OES Faculty Publications

Turbulent mixing of salt is examined in a shallow salt wedge estuary with strong fluvial and tidal forcing. A numerical model of the Merrimack River estuary is used to quantify turbulent stress, shear production, and buoyancy flux. Little mixing occurs during flood tides despite strong velocities because bottom boundary layer turbulence is dislocated from stratification elevated in the water column. During ebbs, bottom salinity fronts form at a series of bathymetric transitions. At the fronts, near-bottom velocity and shear stress are low, but shear, stress, and buoyancy flux are elevated at the pycnocline. Internal shear layers provide the dominant source …

Chemical Composition And Antimicrobial Activity Of The Essential Oils Of Mosses (Tortula Muralis Hedw., Homalothecium Lutescens (Hedw.) H. Rob., Hypnum Cupressiforme Hedw., And Pohlia Nutans (Hedw.) Lindb.) From Turkey, Osman Üçüncü, Tayyi̇be Beyza Cansu, Turan Özdemi̇r, Şengül Alpay Karaoğlu, Nuretti̇n Yayli

Turkish Journal of Chemistry

The essential oils of mosses [Tortula muralis Hedw. (Pottiaceae), Homalothecium lutescens (Hedw.) H. Rob. (Brachytheciaceae), Hypnum cupressiforme Hedw. (Hypnaceae), and Pohlia nutans (Hedw.) Lindb. (Mniaceae)] were investigated by means of GC-FID/MS techniques. The major components were nonanal (18.3%) and tetradecanol (4.3%) in the oil of T. muralis, nonanal (36.8%) and tricosane (6.5%) in the oil of H. lutescens, nonanal (12.5%) and 2E-tetradecen-1-ol (6.9%) in the oil of H. cupressiforme, and nonanal (7.8%) and 2E-tetradecen-1-ol (7.1%) in the oil of P. nutans. The essential oils of T. muralis, H. lutescens, H. cupressiforme, and P. nutans were rich as in non-terpenoid components …

Synthesis And Antimicrobial Activities Of Some New 1,2,4-Triazole Derivatives, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Hacer Bayrak, Hakan Bektaş, Şengül Alpay Karaoğlu

Turkish Journal of Chemistry

The synthesis of ethyl [3-(cyanomethyl)-5-alkyl-4H-1,2,4-triazol- 4-yl]carbamates (2a-d) was performed starting from ethyl 2-[ethoxy(4- (aryl)methylene]hydrazinecarboxylates (1a, 1b). The treatment of 2a with thiosemicarbazide afforded ethyl [3-[(5-amino-1,3,4-thiadiazol- 2-yl)methyl]-5-(4-nitrophenyl)-4H-1,2,4-triazol-4-yl]carbamates (3a), whereas compound 2b produced 5-{[4-amino-5-(4-methylphenyl)- 4H-1,2,4-triazol-3-yl]methyl}-1,3,4-thiadiazol-2-amine (3b) in the same reaction conditions. The treatment of tert-butyl 2-[2-(4-chlorophenyl)-1-ethoxyethylidene]hydrazinecarboxylate (5) with malonohydrazide or cyanoacethydrazide gave the corresponding 1,2,4-triazol-ylcarbamate derivatives (6 or 9); then the hydrolysis of these compounds resulted in the formation of 3-{[4-amino-5-(4- chlorobenzyl)-4H-1,2,4-triazol-3-yl]methyl}-5-(4-chlorobenzyl)-4H- 1,2,4-triazol-4-amine (7) and [4-amino-5-(4-chlorobenzyl)-4H- 1,2,4-triazole-3-yl]acetonitrile (10), respectively. The synthesis of the Schiff base derivatives 3-(4-chlorobenzyl)-5-{[5-(4-chloroben- zyl)-4-[(2-hydroxyphenyl-methylene)amino]-4H-1,2,4-triazol-3-yl]methyl} -N-(2-hydroxyphenylmethylene)-4H-1,2,4-triazol-4-amine (8), and (5-(4-chlorobenzyl)-4-{[(2,6-dichlorophenyl)methylene]amino}-4H-1,2,4- triazol-3-yl)acetonitrile (12) was performed from the reaction of compounds 7 …

Nile Blue-Hexacyanoferrate Carbon Paste Modified Electrode As An Amperometric Sensor For Determination Of Hydrazine, Reza Sabzi, Elnaz Minaie, Khalil Farhadi, Mirmaqsoud Golzan

Turkish Journal of Chemistry

The main problem associated with metal hexacyanoferrates (MHCFs) is their instability at high pH values. We synthesized a new Prussian Blue analogue, Nile-Blue hexacyanoferrate (NBHCF), that remains stable in 0.2 M KOH. A carbon paste (CPE) chemically modified electrode (ME) containing NBHCF was prepared as a stable electrochemical sensor for measuring hydrazine. A detailed characterization of the electrochemical and electrocatalytic behavior of NBHCF was performed using cyclic voltammetric, chronoamperometric, differential pulse voltammetric (DPV) and hydrodynamic amperometric methods. The NBHCF-modified electrode produced reproducible redox peaks and resulted in a linear increase in the oxidation signal of hydrazine with increasing concentration of …

Determination Of Trace Element Contents Of Thymus Species From Turkey, Fatümetüzzehra Küçükbay, Ebru Kuyumcu

Turkish Journal of Chemistry

Eleven mineral and trace elements (Mg, Ca, K, Fe, Mn, Al, Zn, Cu, Cd, Ni, and Pb) were determined in the Thymus species growing in Turkey. The total concentrations were measured in samples mineralized with concentrated nitric acid and hydrogen peroxide in a microwave system. The determination of mineral and trace elements in the leaves of the Thymus species was carried out by flame and graphite furnace atomic absorption spectrometry. The accuracy of the method was ensured by using standard reference material (NIST-SRM 1515 apple leaves). The concentration of elements in the Thymus species and their biological activity on humans …

Cover And Contents

Turkish Journal of Chemistry

No abstract provided.

Electrochemical Impedance Spectroscopic Studies Of The Passive Layer On The Surface Of Copper As A Function Of Potential, Amtul Naseer, Athar Khan

Turkish Journal of Chemistry

Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to investigate the oxide layer formed on a copper disc electrode and the changes that took place when treated potentiostatically in the range of -0.3 V to 0.9 V in buffer of pH 8.5. The response of an electrode using EIS, initially at equilibrium, to an applied potential was then modeled with equivalent circuits, proposed for different potential regions that completely illustrated the Cu/oxide/electrolyte systems and their properties in terms of 2 interfaces. Criterion for the applicability of equivalent circuit models was discussed. Changes in the film/metal interface as a …

Solid Phase Extraction Of Copper, Nickel, And Cobalt In Water Samples After Extraction Using Surfactant Coated Alumina Modified With Indane-1,2,3-Trione 1,2-Dioxime And Determination By Flame Atomic Absorption Spectrometry, Mahdi Hosseini, Nasser Dalali, Ali Karimi, Kourosh Dastanra

Turkish Journal of Chemistry

A simple method for simultaneous pre-concentration of Cu, Ni, and Co metal ions prior to their determination by flame atomic absorption spectrometry is reported. The method is based on the extraction of target ions via complexation with indane-1,2,3-trione 1,2-dioxime immobilized on sodium dodecyl sulfate (SDS) coated alumina. The metal content on the adsorbent was eluted with 4.5 mL of 2 mol L^{-1} nitric acid. The influences of the analytical parameters including pH, sample volume and flow rate, and eluent type and flow rate were investigated. The effect of matrix ions on the retentions of the analytes was also examined. The …

Co(Iii) Catalysed Asymmetric Ring-Opening Of Epichlorohydrin By Salicylaldehyde Derivatives: Reversal Of Enantioselectivity And Rate Acceleration On Addition Of Alcl_3, Leman Karadeni̇z, Gamze Koz, Kadri̇ye Aydin, Stephen Thomas Astley

Turkish Journal of Chemistry

Using asymmetric Cobalt(III) salen catalysts, the ring-opening of epichlorohydrin by 2,3-dihydroxybenzal- dehyde and 2,4- dihydroxybenzaldehyde was found to occur at the phenolic groups most distant from the aldehydic group. Switching catalysts afforded a reversal in enantioselectivity. For 2,3-dihydroxybenzaldehyde and salicylaldehyde, addition of AlCl_3 to the reaction mixture led to an increase in reaction rate without any decrease in product enantiopurity.