bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of Octa-O-acetyl-tris(N-ethoxycarbonyl)destomycin A
Authors: Horito Shigeomi , Ohashi Yuji , Gassner Nobert , Yoshimura Juji , Sasada Yoshio 
Published: July 2006

Abstract
The molecular and crystal structure of octa-O-acetyl-tris(N-ethoxycarbonyl)destomycin A tetrahydrate, C45H65N3O27·4H2O, has been determined by X-ray analysis. The space group is P21 with a=14.738(4), b=17.391(4), c=12.171(4) Å, β=105.58(4)°, and Z=2. The structure was solved by the direct method, and the least-squares refinement using 4008 reflections led to the final R value of 0.12. The configuration of the ortho ester carbon atom is (R). The d-talose moiety has the boat conformation whereas the other rings are in the chair form.
Reaction of Organoaluminium Reagents with Cyclopropylmethyl Acetates and 2-Vinylcyclopropane-1,1-dicarboxylate Esters
Authors: Hiyama Tamejiro , Morizawa Yoshitomi , Yamamoto Hajime , Nozaki Hitosi 
Published: July 2006

Abstract
Ring-opening alkylation of cyclopropylmethyl acetates was studied. The acetoxyl group of 7-(1-acetoxyheptyl)norcarane is substituted by the alkyl group upon treatment with trialkylaluminium, but alkylation of trans-1-(1-acetoxyethyl)-2-phenylcyclopropane with trialkylaluminium gives rise to trans-5-phenyl-2-alkenes. The reaction of (1S,2S)-2-phenylcyclopropylmethyl acetate with trimethylaluminium resulted in the complete loss of optical activity to give racemic 4-phenyl-1-pentene. Alkylation of trans-1-(1-acetoxy-3-phenylpropyl)-2-vinylcyclopropane with trialkylaluminium proceeds under regioselective ring-opening to give 3-alkylated trans-8-phenyl-1,5-octadiene (selectivity 73–83%). The regio- and stereochemistry of homoconjugate addition to activated vinylcyclopropanes having a doubly carbonyl substituted ring carbon was studied. Trialkylaluminium on addition to diethyl 2-vinylcyclopropane-1,1-dicarboxylate in a 1,5-manner afford diethyl (2-alkyl-3-butenyl)propanedioate (over 96% selectivity). In contrast, the reaction of this cyclopropane with tetraalkylaluminiumlithium takes place in a 1,7-manner to give diethyl (trans-4-alkyl-2-butenyl)propanedioate with 88–92% selectivity. Clean regiocontrol of the reaction is observed in the methylation of ethyl exo-6-(trans-1-propenyl)-2-oxobicyclo[3.1.0]hexane-1-carboxylate with trimethylaluminium or tetramethylaluminiumlithium. Alkylation with trimethylaluminium proceeds with 86% inversion of the configuration at C(6) of the substrate, affording (2R*,3R*)-2-ethoxycarbonyl-3-[(S*)-trans-1-methyl-2-butenyl]cyclopentanone which is transformed into neonepetalactone.
Branched-chain Sugars. XXII. Synthesis of Benzyl 2,3-Di-O-benzyl- and 2,3-O-Methylene-β-l-threo-pentopyranosid-4-uloses, and the Corresponding 6-Deoxy-α-d-xylo-hexopyranosid-4-uloses
Authors: Matsuzawa Masafumi , Kubo Kazusuke , Kodama Hisashi , Funabashi Masuo , Yoshimura Juji 
Published: July 2006

Abstract
The title compounds were synthesized from l-arabinose and d-glucose as intermediates to a few naturally occuring branched-chain sugars. Oxidation conditions of precursors to the corresponding 4-uloses were examined.
Syntheses of [1]Benzopyrano[4,3-c]pyrazoles and -[3,4-d]isoxazoles
Authors: Shimizu Tomio , Hayashi Yoshiyuki , Yamada Kazunari , Nishio Toshiyuki , Teramura Kazuhiro 
Published: July 2006

Abstract
The reaction of 2H-1-benzopyran with several 1,3-dipoles gives cycloadducts in good yields. The orientation of the cycloaddition is qualitatively interpreted in terms of FMO theory. These heteropolycyclic compounds were also obtained from hydrazones of 3-aroyl-2H-1-benzopyrans, prepared from 3-cyano-2H-1-benzopyran.
Mixed Monolayers of Long Normal-chain Fatty Acids with Long Normal Alkyl Esters. III. Pentadecanoic Acid-Esters System
Authors: Matuo Hirosi , Motomura Kinsi , Matuura Ryohei 
Published: July 2006

Abstract
The surface pressures of mixed monolayers of pentadecyl acetate, hexadecyl acetate, heptadecyl acetate, and hexadecyl propionate with pentadecanoic acid were measured at various compositions and temperatures. The two-dimensional phase diagram and apparent molar entropy and energy changes were evaluated by means of a previously described thermodynamic treatment. They depend uniquely on the molecular structure of the film-forming substances and on the composition in the mixed monolayer. The phase diagrams of pentadecanoic acid–pentadecyl acetate and pentadecanoic acid–hexadecyl acetate systems are of a complicated type. There are positive and negative regions in the excess apparent molar energy changes. The pentadecanoic acid–heptadecyl acetate and pentadecanoic acid–hexadecyl propionate systems are of the positive azeotropic type. The excess apparent molar energy changes are positive over the whole range of mole fractions.
The Enantioface-differentiating (Asymmetric) Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXXVI. The Development of Modified Nickel Catalysts with High Enantioface-differentiating Abilities
Authors: Harada Tadao , Yamamoto Mihoko , Onaka Shinji , Imaida Motomasa , Ozaki Hiroshi , Tai Akira , Izumi Yoshiharu 
Published: July 2006

Abstract
Various types of modified nickel catalysts were prepared and their enantioface-differentiating (asymmetric) abilities were examined. It was found that the presence of aluminum or related metal compounds in the catalyst was unfavorable for the effective enantioface-differentiating catalyst. The modification with a solution containing tartaric acid and inorganic salt gave a high enantioface-differentiating ability to Raney nickel and reduced nickel catalyst. Among the modified nickel catalysts examined, the Raney nickel modified with tartaric acid and sodium bromide gave the best result with respect to the hydrogenation activity and enantioface-differentiating ability (optical yield 88%). NaBr adsorbed on Raney nickel was found to inhibit the nonenantioface-differentiating hydrogenation.
Oxygenation of Aromatic Vinyl Ethers. A Noticeable Formation of Epoxides and Reaction Mechanism
Authors: Kanno Tatsuya , Hisaoka Motoyuki , Sakuragi Hirochika , Tokumaru Katsumi 
Published: July 2006

Abstract
cis-β-Alkoxystyrenes such as cis-β-methoxy-, cis-β-ethoxy-, and cis-β-isopropoxystyrene were autoxidized as neat at room temperature in the dark even in the absence of any radical generator. UV-irradiation and the use of a radical generator facilitated the oxygenation of these olefins. These oxidations afforded the corresponding epoxides or their derivatives in considerable yields as well as carbonyl compounds resulting from oxidative cleavage of the double bonds. The mechanisms for these oxidations are proposed to involve free-radical chain pathways and charge-transfer complexes between the olefins and oxygen which play an important role in the initiation steps.
Migrated Lupane Derivatives. Boron Trifluoride Etherate-catalyzed Backbone Rearrangement of 3α,4α- and 3β,4β-Epoxy- D : A-friedo-18β,19αH-lupanes and Solvent Effects
Authors: Yokoyama Yasushi , Moriyama Yoshihiko , Tsuyuki Takahiko , Takahashi Takeyoshi 
Published: July 2006

Abstract
Backbone rearrangements of 3α,4α- and 3β,4βepoxy-D:A-friedo-18β,19αH-lupanes catalyzed by boron trifluoride etherate gave 18β,19αH-lup-12-en-3-ols, lup-18-en-3-ols, and lup-19-en-3-ols, besides known D:B-friedo-18β,19αH-lup-5-en-3-ols and -5(10)-en-3-ols. D:B-Friedo-18β,19αH-lup-l(10)-en-3α-ol and 3β,10β-epoxy-D:B-friedo-18β,19αH-lupane were also obtained from α- and β-epoxides, respectively. Solvent effects on these reactions were examined.
Oxidative Cleavage Reaction of 3-Substituted Indoles Catalyzed by CuCl–Pyridine Complex under Oxygen
Authors: Tsuji Jiro , Kezuka Hiroaki , Takayanagi Hiroshi , Yamamoto Keiji 
Published: July 2006

Abstract
Oxidative cleavage of 3-methylindole using a catalytic amount of copper(II) salts with added pyridine under an oxygen atmosphere was studied. Smooth cleavage of 3-methylindole took place to give 2-formamidoacetophenone in 73–80% yield, whereas exclusive formation of a hydrate compound derived from 3,3′-dimethyl-3,3′-bi-3H-indole resulted under anaerobic conditions. Clean oxidative cleavage of N-acetyltryptamine, methyl 3-indolylacetate, and methyl 2-acetamido-3-(3-indolyl)propionate was also achieved, constituting a mimic of tryptophan-2,3-dioxygenase.
Restricted Rotation Involving the Tetrahedral Carbon. XXXIX. 9-(2-Methoxy-1-methylethyl)triptycene Derivatives
Authors: Suzuki Masahiko , Yamamoto Gaku , Kikuchi Hiromi , Oki Michinori 
Published: July 2006

Abstract
9-(2-Methoxy-1-methylethyl)triptycenes were prepared from 9-(2-methoxy-1-methylethyl)anthracene and corresponding benzynes to examine the feasibility of isolating rotational isomers of 9-isopropyltriptycene derivatives at room temperature. They afforded crystalline ap forms which underwent internal rotation with activation energies of ca. 23 kcal/mol. 9-(2-Acetoxy-1-methylethyl)-1,2,3,4-tetrachlorotriptycene gave similar results. Based on the results, the barrier to rotation of 9-isopropyl-1,2,3,4-tetrabromotriptycene was reexamined to show that it must be corrected as 23.5 kcal/mol at 175 °C.
Configuration and Conformation of the Photoisomers of N-[p-(Dimethylamino)benzylidene]anilines
Authors: Yoshida Masato , Kobayashi Michio 
Published: July 2006

Abstract
The UV, 1H-NMR, and 13C-NMR spectra of the photoisomers produced by irradiation of N-[p-(dimethylamino)benzylidene]anilines at low temperature have been studied. The results suggested that the photoisomers have Z structures and the imino benzene rings are twisted around the Ar–N axis out of Ar–CH=N plane due to the steric repulsion between the two rings.
Spectroscopic Studies of Surfactant Solubility. III. Side-chain Effects of Phosphatidyl Compounds in Chloroform Solutions
Authors: Okazaki Mitsuyo , Hara Ichiro , Tsutsui Yumiko K , Fujiyama Tsunetake 
Published: July 2006

Abstract
The infrared spectra of phosphatidyl and related compounds were studied with respect to their side-chain effects on solubility. It was clarified that the existence of a hydrogen-bonding between chloroform and a phosphate group is essential for these phosphatidyl compounds to form stable solutions in chloroform. The existence of double alkyl-chains and acyloxyl groups is clarified to be very useful for those compounds to have a strong solvent-phobic character without losing their solubility in solvents. The role of a choline moiety was also clarified. The details of the analysis of the infrared intensity were also described. It was emphasized that the intensity enhancement due to hydrogen-bond formation can be quantitatively related to the enthalpy change due to hydrogen-bond formation.
The Reaction of Diazo Ketones in the Presence of Metal Chelates. VIII. The Stereochemistry of the 1,3-Dipolar Cycloaddition of 1-Methoxy- 2-benzopyrylium-4-olates to Ethylenic Dipolarophiles
Authors: Ibata Toshikazu , Jitsuhiro Kimiko , Tsubokura Yoshie 
Published: July 2006

Abstract
1,3-Dipolar cycloadducts were obtained in the reactions of 1-methoxy-2-benzopyrylium-4-olate (3a) with ethylenic dipolarophiles, such as dimethyl fumarate, dimethyl maleate, maleic anhydride, trans-1,2-dibenzoylethylene, N-substituted maleimides, and acenaphthylene. The configuration of the adducts was determined on the basis of the NMR coupling pattern of the methine protons of the adducts in connection with a deuterium experiment. The previously reported structure of the adduct of 3a with dimethyl fumarate was corrected according to the experimental results obtained using 3-deuterated 3a. The stereospecificity of the cycloaddition was confirmed in the reactions of dimethyl fumarate, dimethyl maleate, and trans-1,2-dibenzoylethylene; this stereospecificity was explained by the concerted (π2S+π4S) mechanism. The exo/endo ratios of the adducts of N-substituted maleimides may be explained by the combination of the steric repulsion and π-π interaction of the phenyl ring of 3 and the substituent on the N-atom of maleimides. The cycloadditions of 1-methoxy-3-methyl-2-benzopyrylium-4-olate with N-substituted maleimides were also explained in a similar manner.
On the Extractability of Univalent Cation as Dibenzo-18-crown-6 Complexes with Picrate Ion
Authors: Hasegawa Yuko , Wakabayashi Hiroji , Sakuma Manabu , Sekine Tatsuya 
Published: July 2006

Abstract
The solvent extractions of alkali metal(I) with dibenzo-18-crown-6 (the nomenclature recommended by IUPAC is 2,3,1l,12-dibenzo-1,4,7,10,13,16-hexaoxacyclooctadeca-2,11-diene) as the picrate into chloroform and benzene were studied at 25°C and compared with those of other univalent ions. The extraction constants of the metal ions (Kex0=[ME+A−]org[M+]−1[E]org−1[A−]−1), are in the sequence of Tl+\simeqK+&gt;Rb+&gt;NH4+≥Ag+&gt;Cs+&gt;Na+, but the extraction constants of the metal complexes (Kex=[ME+A−]org×[ME+]−1[A−]−1) are NH4+\simeqTl+\simeqRb+\simeqK+&gt;Cs+\simeqAg+&gt;Na+.
Visible Light-induced Oxidation of Ascorbic Acid and Formation of Hydrogen Peroxide
Authors: Kurimura Yoshimi , Yokota Hiroshi , Muraki Yuko 
Published: July 2006

Abstract
Photosensitized oxidation of ascorbic acid and the formation of hydrogen peroxide using tris(2,2′-bipyridine)ruthenium(II), Ru(bpy)32+, proceed simultaneously in oxygen containing an aqueous solution of ascorbic acid with the illumination of visible light. The mechanism of the reaction has been suggested from the rate dependence on the solute concentrations and from quenching experiments. The charge separation could be achieved as the result of scavenging Ru(bpy)33+, which is formed by the reaction of the lowest excited state species of Ru(bpy)32+ with O2.
X-Ray Structures of Di-μ-oxo, μ-Oxo-μ-thio-, and Di-μ-thio-μ-[(R)propylenediaminetetraacetato]-bis[oxomolybdate(V)] Ions
Authors: Kojima Akinobu , Ooi Shun’ichiro , Sasaki Yoichi , Suzuki Kimiko Z , Saito Kazuo , Kuroya Hisao 
Published: July 2006

Abstract
The crystal structures of Na2[Mo2O4(R-pdta)]·3H2O (1), Na2[Mo2O3S(R-pdta)]·4H2O (2), and Na2[Mo2O2S2(R-pdta)]·4H2O (3) have been determined from difTractometer data collected by the use of Mo Kα radiation. The structures of 1, 2, and 3 were refined by the least-squares method to R 0.064, 0.040, and 0.058 for 1370, 2794, and 2141 nonzero reflections respectively. Each Mov ion has a distorted octahedral coordination, and the two coordination octahedra share a common edge to form a binuclear complex. Two terminal oxo ligands are cis to the bridging oxide or sulfide. The R-pdta4− ligand bridges two Mov ions, yielding a Mo–N–CH2–CH(CH3)–N–Mo ring with an equatorial methyl group, the N and carboxyl O atoms occupying the axial (trans to the terminal O) and equatorial positions respectively. A specific distortion of the donor-atom disposition is observed, which is represented as the twist (Δ) of the terminal O–O edges in the (Remark: Graphics omitted.) portion about the axis passing through the mid-points of the O–O edges (Δ denotes the absolute disposition of two skew edges or bonds), and as the twist (Δ) of Mo–N bonds about the Mo–Mo axis. The O=Mo bonds of the O=Mo–Mo=O segment in 1 twist in Δ, but those in 2 and 3 are virtually parallel. The distortion of donor-atom disposition is discussed on the basis of the strain due to chelate-ring formation.
Kinetic Studies of Fast Equilibrium by Means of High-performance Liquid Chromatography. II. Ligand Exchange of N,N-Disubstituted Dithiocarbamate Chelates of Ni(II)
Authors: Moriyasu Masataka , Hashimoto Yohei 
Published: July 2006

Abstract
The equilibrium of the ligand exchange of labile Ni(II) dialkyldithiocarbamate chelates (MA2+B\ightleftharpoonsMAB+A, MAB+B\ightleftharpoonsMB2+A, K1=[MAB][A]/[MA2][B], K2=[MB2][A]/[MAB][B]) has been investigated by means of high-perfromance liquid chromatography, two solutions of MA2 and B being mixed and then equilibrated. The equilibrium constants, K1 and K2, have been determined by measuring the concentrations of each complex, including the kinetically unstable ternary complex in the equilibrium state. The ratio of the stability constants of the two Ni(II) chelates, which is equal to K1K2, has been calculated. The following series of increasing stability constants has been found for the alkyl substituents in chloroform; tetramethylene&lt;dimethyl&lt;pentamethylene&lt;diethyl&lt;hexamethylene&lt;dipropyl&lt;dibutyl. The rate of ligand exchange has been investigated by mixing very dilute MA2 and B and by injecting the mixture into HPLC after the lapse of a certain time. The rate of ligand exchange is slow when low initial concentrations of MA2 and B are chosen. The rate of ligand exchange is more than ten times faster than that of ternary complex formation.
Applications of Homogeneous Water-gas-shift Reaction. II. The Formation of Dipropyl Ketones as Primary Products from CO and H2O in the Presence of an Excess Amount of Propene. Cobalt-based Catalytic Hydrocarbonylation
Authors: Murata Kazuhisa , Matsuda Akio 
Published: July 2006

Abstract
The hydrocarbonylation of propene with CO and H2O to give dipropyl ketones occurs predominantly over forming C4-aldehydes; the catalyst solutions employed are prepared in situ from Co2(CO)8, various phosphines as ligands, and H2O, a high molar ratio of propene to Co2(CO)8 of 300/2 being required. Of the several phosphorus ligands examined, 1,2-bis(diphenylphosphino) ethane (diphos) and bis(diphenylphosphino) acetylene are relatively effective for the formation of the ketones (abbreviated as [ketones]). The effects of the reaction variables (CO pressure, temperature, and H2O concentration) on [ketones] are also examined using the Co2(CO)8–diphos system; [ketones] increases with the initial increase in CO pressure, but reaches a maximum at ca. 100 kg/ cm2 and decreases thereafter. Pronounced decreases of [ketones] are observed when pyridine as well as hydrogen is added to the catalyst solutions.
The Oxidation Products of Tetracyanoferrate(II) Chelates with Optically Active 1,2-Diamines: Tetracyano(1,2-diamine)ferrate(III)s and Tetracyano(1,2-diimine)ferrate(II)s
Authors: Goto Masafumi , Takeshita Michihiro , Sakai Tomoya 
Published: July 2006

Abstract
Optically active diamagnetic title complexes were oxidized with hydrogen peroxide under acidic and basic aqueous conditions. The corresponding low-spin tetracyano(diamine)ferrate(III) complexes with (R)-1,2-propanediamine, (1R,2R)-1,2-cyclopentanediamine, and (1R,2R)-1,2-cyclohexanediamine as diamines formed under acidic conditions and were characterized with several spectral measurements including the CD spectra. Each CD spectrum showed a moderate positive Cotton effect at ca. 24700 cm−1 and was assigned to a d-d transition. However a ligand oxidation took place, yielding tetracyano(1,2-diimine)ferrate(II) complexes under neutral and basic conditions; their electronic and 1H- and 13C-NMR spectra are also reported.
Preparation of (E)-1,3,5-Hexatriene and (3E, 5E)-1,3,5,7-Octatetraene by the Palladium Catalyzed Elimination of Acetic Acid from Allylic Acetates
Authors: Yamamoto Keiji , Suzuki Shigeaki , Tsuji Jiro 
Published: July 2006

Abstract
Palladium complex-catalyzed elimination of acetic acid from (2E,4E)-2,4-hexadienyl acetate and (2E, 4E, 6E)-2,4,6-octatrienyl acetate afforded, respectively, the title conjugated polyenes stereoselectively.
Pressure and Temperature Dependence of NMR Spin-lattice Relaxation in Plastic 2,2-Dimethylpropanoic Acid
Authors: Hasebe Tooru , Soda Gen , Chihara Hideaki 
Published: July 2006

Abstract
Proton spin-lattice relaxation time T1 of 2,2-dimethylpropanoic acid in its plastic phase was measured at 10 MHz up to 120 MPa between 268 K and 330 K. A minimum in T1 appears in the low-pressure region which is due to overall reorientation of molecules. The T1 minimum value decreases as the pressure increases in a way different from simple-minded prediction. The activation volume, 25±3 cm3 mol−1, is twice as large as in other plastic crystals when normalized by the molar volume. The pressure dependence of the activation enthalpy is also about twice as large. These can be rationalized by considering associated dimers as the reorienting unit. The phase diagram is given and the volume changes associated with the transition and with the fusion were derived (15.6 and 5.86 cm3/mol of dimer).
1,3-Dipolar Cycloaddition Reaction of Vinyl Azides with Enamines. Synthesis of Vinyltriazolines and Vinyltriazoles
Authors: Nomura Yujiro , Takeughi Yoshito , Tomoda Shuji , Ito Masato M 
Published: July 2006

Abstract
Reaction of α- and β-azidostyrene with enamines gave vinyltriazolines regioselectively in moderate yields. 1-Pyrrolidinyl enamines reacted with α-azidostyrene more readily than piperidino or morpholino enamines. β-Azidostyrene was as reactive as azidobenzene while α-azidostyrene was much less reactive. Vinyltriazolines formed from enamines of ketones were deaminated to yield the corresponding vinyltriazoles.
ESR Spectra and Structure of the Radical Anions of Organo Halosilanes
Authors: Hasegawa Akinori , Nagayama Akihiro , Hayashi Michiro 
Published: July 2006

Abstract
The radical anions of ethyl- and vinyl- halosilanes formed in solid matrices of tetramethylsilane and their ESR spectra were investigated to be compared with results obtained from related radical anions. These radical anions have a trigonal bipyramidal structure with two axial and two equatorial positions. Ethyl and methyl groups which are less electronetative than H prefer the equatorial positons. The vinyl group with a single π electron system occupies the equatorial position due to its electron-donating capability, in spite of its larger electronegativity.
The Capillary-tube Isotachophoretic Determination of Sodium(I), Magnesium(II), Calcium(II), Strontium(II), and Barium(II) Using Complex-forming Equilibria between CyDTA and the Metal Ions
Authors: Nukatsuka Isoshi , Taga Mitsuhiko , Yoshida Hitoshi 
Published: July 2006

Abstract
The capillary-tube isotachophoresis technique was used to determine sodium(I), magnesium(II), calcium(II), strontium(II), and barium(II). The complex-forming equilibria between CyDTA and the metal ions were used to expand the differences among their effective mobilities. The mobilities of IIa metal ions decreased with increases in the pH of the leading electrolytes and in the CyDTA concentration in the leading electrolytes. The simultaneous determination of the above five cations could be performed when the pH of the leading electrolyte was adjusted at 5.5 or above. The relative standard deviations were 1.7–2.2% for determining 15.0–25.0 nmol of the cations when the pH of the leading electrolyte was 5.70. Magnesium(II) and calcium(II) ions underwent “enforced isotachophoretic” migration.
The Spectrophotometric Determination of Ethylene Diamine with Phthalaldehyde and 2-Mercaptoethanol
Authors: Hihara Goro , Miyamae Hiroshi , Nagata Miharu 
Published: July 2006

Abstract
A simple spectrophotometric method has been developed for the determination of ethylenediamine in an aqueous or ethanolic solution. This method is based on the reaction of ethylenediamine with phthalaldehyde and 2-mercaptoethanol, and on the measurement of the absorbance of the yellow-developed solution at 430 nm. Beer’s law holds for 0.5–10 μg of ethylenediamine per 1 ml. Secondary and tertiary amines do not interfere with theestimation. Two of the primary amines, diethylenetriamine and triethylenetetramine, interfere with the estimation when present in quantities of more than 10 μg per ml of the sample solutions. 1,3-Propanediamine interferes seriously. The colored compound was found to be composed of ethylenediamine, phthalaldehyde, and 2-mercaptoethanol in a molar ratio of 1:2:1.