bluuebunny/crossref_metadata_2025_split huggingface dataset:
Negative Photoconduction in Solution of Aromatic Amine and Benzoquinone by Flash Excitation
Authors: Nakata Jun-ichi , Imura Takeshi , Kawabe Kazuo 
Published: July 2006

Abstract
The conductivity of a solution of benzoquinone and TMPD decreased after being subjected to flash excitation. This is attributed to the decrease of free ions due to the equilibrium shift produced by photo-induced disappearence of the ion pair.
The Effect of Partial Deuteration on the Phosphorescence Lifetime of N,N,N′,N′-Tetramethyl-p-phenylenediamine
Authors: Yoshida Nobutoshi , Ebara Nozomu 
Published: July 2006

Abstract
A position-dependent deuterium effect on the phosphorescence lifetime of N,N,N′,N′-tetramethyl-p-phenylenediamine was found. Aromatic ring protons and methyl protons were shown to contribute to the radiationless transition independently and differently. Important terms in the decay constant are briefly discussed.
Densities and Molar Volumes of Molten Binary PrCl3–KCl, PrCl3–NaCl, PrCl3–CaCl2, NdCl3–KCl, NdCl3–NaCl, NdCl3–CaCl2 Systems
Authors: Mochinaga Junichi , Igarashi Kazuo 
Published: July 2006

Abstract
The densities of PrCl3, NdCl3, PrCl3–KCl, PrCl3–NaCl, PrCl3–CaCl2, NdCl3–KCl, NdCl3–NaCl, and NdCl3–CaCl2 melts measured dilatometrically were represented by the empirical equations as functions of temperature. The molar volumes of the melts were calculated from the density data.
The Reactions of Cyclic Sulfilimines with Cyanide Ion and Phosphine: Evidence for Substitution on Trivalent Sulfur
Authors: Aida Tetsuo , Nakajima Masashi , Inoue Teruhiko , Furukawa Naomichi , Oae Shigeru 
Published: July 2006

Abstract
The effect of ring size on the reaction of N-p-tosylsulfilimine with such nucleophiles as CN− and n-Bu3P was investigated kinetically and compared with the effect on the reaction of the corresponding cyclic sulfonium salt. The results indicated that the SN2–S process is more probable than the SN2–N route.
Reaction of 1,3-Oxazinium Salt with Active Methylene Compounds
Authors: Shibuya Isao , Kurabayashi Masahiro 
Published: July 2006

Abstract
2,4,6-Triphenyl-1,3-oxazinium perchlorate reacts with active methylene compounds to give several butadiene derivatives and various pyridine derivatives. The reactions seem to proceed as follows: The carbanion from an active methylene compound attacks the 6-position of the oxazinium ring, and opens the ring to form a butadiene as an intermediate, which is then recyclized to a pyridine derivative according to a characteristic mode. The mode of recyclization differs with the constituent of each active methylene. There are five modes characteristic of cyano-, ester-, amido- and benzoyl constituents and nitromethane. A compound containing two different constituents usually follows either of the two possible modes.
Photoreaction of Bicyclo[5.3.0]dec-1(7)-en-2-one with Cyclopentene and Cyclohexene
Authors: Kunai Atsutak , Omori Takeshi , Kimura Koji , Odaira Yoshinobu 
Published: July 2006

Abstract
The photoreaction of the enone (I) with cyclopentene gave the radical coupling products, (VII) and (VIII), along with the hydrogen abstraction product (VI), but not [2π+2π] photocycloadduct. On the other hand, the photoreaction of I with cyclohexene proceeded in somewhat different manner to give the [2π+2π] photocycloadduct (V) other than the hydrogen abstraction product (VI) and the radical coupling product (IX).
Oxidation by Iron(III) Complexes. IX. The Preparation of α-Diketones by the Oxidation of Enolizable Ketones with the Iron(III) Chloride–Pyridine Complex under Oxygen
Authors: Inoue Hiroo , Hata Hiroyuki , Imoto Eiji 
Published: July 2006

Abstract
The oxidation of deoxybenzoin and p-substituted deoxybenzoins with an iron(III) chloride–pyridine complex under air or oxygen was investigated. The reaction afforded the corresponding α-diketones in a satisfactory yield.
The Synthesis and Polymerization of 2-(p-Vinylphenyl)-4,6-diamino-s-triazine
Authors: Oikawa Eizo , Horiguchi Kazuya 
Published: July 2006

Abstract
A new olefinic s-triazine, that cited in the title, was prepared by the reaction of p-cyanostyrene with dicyandiamide. Methyl p-vinylbenzoate could provide the triazine in an improved yield. The triazine readily underwent radical polymerization in an aprotic solvent to give a soluble and thermally stable polymer.
Syntheses and Ring Opening Reactions of 2-Alkyl-3,3-dichlorospiro-[cyclopropane-1,9′-fluorene] Derivativatives
Authors: Wada Eiji , Fujisaki Shizuo , Nagashima Akiko , Kajigaeshi Shoji 
Published: July 2006

Abstract
2-Alkyl-3,3-dichlorospiro[cyclopropane-1,9′-fluorene] derivatives (4) were obtained by the addition of CCl2 to 9-alkylidenefluorenes. Ring opening reactions of 4 with bases gave enynes, butadienes, or butatrienes.
Rate of the Dushman Reaction in Iodic Acid at Low Iodide Concentration. Complexity of Iodic Acid
Authors: Furuichi Ryusaburo , Liebhafsky Herman A 
Published: July 2006

Abstract
Three rate laws have been postulated for the Dushman reaction, 6H++5I−+IO3−=3H2O+3I2, with total reaction orders of four, five and six, at iodide ion concentrations below 10−8 M. New direct measurements of the rate and an examination of thermodynamic data for iodic acid solutions have eliminated some of the confusion. The complexity of iodic acid solutions, with and without added salt, makes it impossible to establish a single reaction order from the radioactive iodine exchange measurements. The new results are best expressed by a quasiempirical rate equation, −d[IO3−]⁄dt=8.59×104[H+]2(I−)[IO3−] mol l−1 min−1, which is closely approximated by −d[IO3−]⁄dt=γ±p4(H+)2(I−)(IO3−){k′+k″(HIO3)} mol l−1 min−1, with k′=2.83×105 mol−3 l3 min−1 and k″=6.60×106 mol−4 l4 min−1 for 25 °C. The second rate law is interpreted in terms of a reasonable mechanism that takes into account the thermodynamically established polymerization in iodic acid solutions.
The Reaction of Hydrogen Atoms with Acetylene
Authors: Ibuki Toshio , Takezaki Yoshimasa 
Published: July 2006

Abstract
The addition of hydrogen atoms to acetylene has been investigated at room temperature. The relative rate constant for
&H+C_2H_4→C_2H_5, \labeleq1
&H+C_2H_2→C_2H_3, \labeleq2
was found to be k1/k2=9.99±0.16. The ratios of the rate constant of disproportionation to that of the combination for the same radicals and for different radicals were determined to be as follows:
2C_2H_5+C_2H_3 &→1-C_4H_8, & & (4)
& →C_2H_6+C_2H_2, & & (4a)
& →2C_2H_4, & & (4b)
k_4a/k_4& =0.369,
k_4b/k_4& =0.68,
C_2H_3+C_2H_3& →1,3-C_4H_6, & & (5)
& →C_2H_4+C_2H_2, & & (5a)
k_5a/k_5& =0.087.
Nucleophilic Substitution on Trivalent Nitrogen Atom. Menschutkin Type Reaction of O-2,4-Dinitrophenylhydroxylamine with Uncharged Nucleophiles
Authors: Yamamoto Fumio , Oae Shigeru 
Published: July 2006

Abstract
Kinetic investigation carried out on the reaction between O-2,4-dinitrophenylhydroxylamine and neutral nucleophiles revealed that the reaction is a typical SN2 reaction on the trivalent nitrogen atom. Moreover, the order of reactivities of common nucleophiles was found to be somewhat similar to that of the nucleophilicities toward sp3 carbon atom. However, unlike the SN2 reaction on sp3 carbon atom, the SN2 reaction on the trivalent nitrogen atom found to be not very sensitive to the steric effect of substituted pyridine.
A Configuration Analysis of the Electronic States of Aniline
Authors: Suzuki Satoshi , Fujii Tsuneo 
Published: July 2006

Abstract
The method of configuration analysis has been applied to the interpretation of the ground and the excited electronic states of aniline. The results of full analysis, including all the singly and the doubly excited configurations, is presented. The electronic wave functions analyzed were obtained by a procedure of the Pariser-ParrPople type. The first excited singlet state of aniline is assigned to the 1Lb. The second, the third, and the fourth excited singlet state are assigned to the mixed state of the 1La and 1CTSl states, the 1CTA, 1Bb, and 1Lb states, and the 1Ba and 1La states respectively. The lowest triplet state of aniline is assigned to the 3La state. The total weights of all the singly excited configurations range from 88% to 95%, except for the ground state. The inclusion of all the doubly excited configurations improves the weights up to 99.6% or more.
Complexes between Nucleotide Base and Amino Acid. I. Crystal Structure of Cytosine: N-Formylglycine
Authors: Ohki Minoru , Takenaka Akio , Shimanouchi Hirotaka , Sasada Yoshio 
Published: July 2006

Abstract
Cytosine: N-formylglycine complex crystallizes in the space group Pna21 with cell dimensions of a=8.444(2), b=21.169(5), and c=5.120(1) Å. The structure was solved by the trial-and-error method on the basis of a Patterson map. A full-matrix least-squares refinement led to an R value of 0.035. The difference map revealed the protonation of cytosine by the carboxyl group of N-acylamino acid and the involvement of ionic interaction in complex formation. This mode is the same as proposed for cytosine: N-benzoylglycine complex in spite of different molecular environment. Such arrangement of cytosine and ionized carboxyl group of amino acid may suggest a mutual recognition scheme between nucleic acid and protein.
Thermal Dehydration and Decomposition of Dioxalato Complexes of Be(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) in Solid State
Authors: Nagase Kenzo , Sato Katsuya , Tanaka Nobuyuki 
Published: July 2006

Abstract
The structures of anhydrous dioxalato complexes K2[M(C2O4)2] (M: Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) prepared by heating their hydrates, were examined by means of infrared absorption and visible reflectance spectroscopy. It was found that the anhydrous complexes of Mn(II), Co(II), and Zn(II) exist in a polynuclear octahedral form with a bridging oxalate group, and those of Ni(II) and Cu(II), in a monomer form. On further heating, the complexes of Be(II), Mn(II), and Zn(II) decomposed into the corresponding metal oxides and potassium oxalate, and those of Co(II), Ni(II), and Cu(II) into the corresponding metals and potassium oxalate. Except for the beryllium(II) complex, the complexes decomposed at lower temperatures with an increase in 1/r, where r is the radius of metal ion.
Thermal Products in the System of NaPO3 Glass-Al2O3
Authors: Watanabe Makoto , Sato Shoji , Saito Hajime 
Published: July 2006

Abstract
The glassy and crystalline products were made by heating a mixture of aluminum oxide and sodium metaphosphate glass with P/Al ratios in the range from 1.0 to 300 at 1000 °C for 3 hr. The crystalline substance was present in the products with P/Al ratios smaller than 5.0 and was, except for aluminum oxide, always aluminum orthophosphate. The quantitative analysis and the measurement of the average chain length of the phosphates contained in the soluble parts of the products showed that aluminum oxide reacts with sodium metaphosphate to make Al–O–P linkages. A theoretical treatment of the average chain length of the polyphosphates present in the aluminate-phosphates was also made. By comparing the calculated average chain length with the measured one, it has been concluded that the most reasonable chemical structure of the glassy products of the aluminate-phosphates is Al(OP)3. By the analysis of the infrared spectra of the thermal products, four-way branching points may be said to exist in the glassy products.
Preparation of cis- and trans-Dicyanobis(ethylenediamine)chromium(III) Complexes and Optical Resolution of the cis Isomer
Authors: Kaizaki Sumio , Hidaka Jinsai , Shimura Yoichi 
Published: July 2006

Abstract
Two geometrical isomers, cis and trans, of [Cr(CN)2(en)2]+ were prepared and the cis isomer was resolved into optical isomers. The ligand field absorption and circular dichroism spectra were discussed and the absolute configuration of cis-(+)546-[Cr(CN)2(en)2]+ was determined to Λ on the basis of the circular dichroism sign in the first spin-allowed d-d band region.
Resins from Formaldehyde. 103. Reaction of Naphthalene with Aqueous Formaldehyde Solution
Authors: Ouchi Tatsuro , Otsuka Saburo , Imoto Minoru 
Published: July 2006

Abstract
The reaction of naphthalene(N) with formaldehyde(F) was carried out in dioxane or an acetic acid/water solution, using sulfuric acid as the catalyst. The rate of the consumption of F is proportional to [N]1.12[F]1.05-[H2SO4]1.05. The activation energies and entropies of the reaction of N, α- and β-naphthyl carbinol(NC) with F were estimated to be 21.4, 15.3, and 16.0 kcal/mol and −19.1, −36.2, and −33.2 e.u., respectively. The reaction products were isolated and their structures were identified as α-NC, αα′-, αβ′-dinaphthylmethane, three-and four-nuclear compounds, which are linked to each other with methylene or methylene ether bonds at the α- or β-positions; identified was done by means of the IR, NMR, and UV spectra, molecular-weight measurements, elemental analysis, and thin-layer chromatography. In addition to the compounds described above, acetyl esters were obtained when the reaction was carried out in the presence of acetic acid. The reactivities of the α-position of N and its derivatives was larger than those of the β-position. Moreover, the resin formation from N and F was studied by means of gel-permeation chromatography. On the bases of these results, the reaction route of N with F to resin was deduced.
Studies of the cis-trans Isomerization of 3-Aryl-1,2,3-oxathiazolidine-2-oxides
Authors: Nishiyama Tomihiro , Yamada Fukiko 
Published: July 2006

Abstract
The isomerization of the cis- or trans-3-aryl-1,2,3-oxathiazolidine-2-oxides was investigated under various conditions. The isomerization proceeded in carbon tetrachloride, chloroform, and benzyl chloride solutions at a low temperature. On the other hand, in other organic solvents, such as benzene, acetone, pyridine, N,N-dimethylformamide, and chlorobenzene, isomerization did not occur. The results can be explained by the mechanism which yields the open-chain halosulfamic acid anion by the attack of a halogen ion on the 5-position. The anion can close to cis- or trans-oxathiazolidine.
Effect of Solvent Viscosity on the Decomposition of 1,1,4,4-Tetraphenyl-2-tetrazene
Authors: Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru 
Published: July 2006

Abstract
The rate of decomposition of 1,1,4,4-tetraphenyl-2-tetrazene (TPT) was measured in the polyethylene glycol (PEG) thickened dimethylformamide (DMF) of varying viscosities. The observed rate constant for the decomposition of TPT decreases with the viscosity of the DMF/PEG solvent system. A compensating change was found in the enthalpy and entropy of activation. It was also found that the decomposition of TPT occurs by the scission of only one N–N single bond, and undergoes cage return in the solvent system by recombination of radicals.
The Synthesis of Heterocyclic Compounds by the Reaction of Tin(II) Bis(acetylacetonate) with Isocyanates
Authors: Wakeshima Ikuko , Kijima Ichiro 
Published: July 2006

Abstract
It was found that phenyl isocyanate reacted with tin(II) bis(acetylacetonate) to yield triphenyl isocyanurate, 5-acetyl-6-methyl-2-oxo-3-phenyl-4-phenylimino-3,4-dihydro-2H-1,3-oxazine, and N,N′-diphenylurea, while ethyl isocyanate reacted with tin(II) bis(acetylaceonate) to afford only 2,4-dioxo-6-ethylimino-1,3,5-triethylhexahydro-1,3,5-triazine.
Studies of Saturated Heterocyclic Compounds. II. The Preparation and PMR Spectroscopic Study of Mono- and Di-substituted-1,3-dioxolan-4-ones
Authors: Asabe Yoshihiro , Takitani Shoji , Tsuzuki Yojiro 
Published: July 2006

Abstract
The relationship of the configurations and the magnitude of the long-range spin coupling constants between the 2-H and 5-H, J2,5, of 1,3-dioxolan-4-ones has been elucidated, the J2,5(trans) value being always larger than the J2,5(cis) value. Geometrical isomers of several 2,5-disubstituted derivatives have been separated by means of preparative tlc and assigned by means of PMR spectroscopy, especially by the use of their J2,5 values. The sign of the J2,5, values for a 2-trichloromethyl derivative has been determined by a partial decoupling experiment, both J2,5(cis) and J2,5, (trans) being positive.
Nuclear Magnetic Resonance Studies of Bicyclic Thiophene Derivatives. II. Through Space H–F Coupling in o-Fluorophenyl Derivatives of Benzoylthiophene, Thienopyrimidine and Thienodiazepine Derivatives
Authors: Hirohashi Toshiyuki , Inaba Shigeho , Yamamoto Hisao 
Published: July 2006

Abstract
Proton–fluorine coupling over six bonds has been observed between fluorine and Hβ of the thiophene ring in ortho fluorophenyl derivatives of 4-phenylthienopyrimidines (1), 2-acetylamino-3-benzoylthiophenes (2), 5-phenyl-1,4-thienodiazepines (3) and 5-phenyl-1,4-thienodiazepine-4-oxides (4). The solvent effect and the N-methylation effect on the coupling constant can be explained by considering that the H–F coupling is a through space coupling. The value of coupling constant (JHF: 0.5 Hz to 4.1 Hz) depends upon the geometry of the ring system condensed at 2-C and 3-C of thiophene ring, decreasing in the order of 1&gt;2&gt;3&gt;4. A discussion is given on the manner of steric repulsion between the benzene ring and some atoms on the other moiety of these compounds.
CNDO/2 Calculations of the Ionization Potentials and Electronic Spectra of Some Unsaturated Hydrocarbons
Authors: Hayashi Toshio , Nakajima Takeshi 
Published: July 2006

Abstract
A modified CNDO/2 method in which local core matrix elements are taken to be empirical parameters is presented. Using this method, the ionization potentials and electronic spectra of some unsatutated hydrocarbons, ethylene, trans-, cis-1,3-butadienes, cyclobutene, cyclopentadiene, benzene and naphthalene, were calculated. The results are in general agreement with the previously available experimental information.
Some Mixed-Ligand Iron(III) Complexes Produced by Reactions of Tris(acetylacetonato)iron(III) with Hydrogen Halides in Organic Solvents
Authors: Takeda Kenji , Isobe Kiyoshi , Nakamura Yukio , Kawaguchi Shinichi 
Published: July 2006

Abstract
Tris(acetylacetonato)iron(III) Fe(acac)3 reacts with an equimolar and double molar amounts of a hydrogen halide in dichloromethane to afford the mixed-ligand iron(III) complexes, FeX(acac)2 and FeX2(acac)H2O, respectively, where X is Cl or Br. They are all high-spin iron(III) complexes and exist as monomeric five-coordinate molecules in non-coordinating solvents, but behave as uni-univalent electrolytes in methanol. Further reactions of FeX2(acac)H2O with an excess of hydrogen halides in dichloromethane followed by the addition of twice as many moles of 1,10-phenanthroline produced [FeX2(phen)2]X. The reactions of FeX2(acac)H2O with excesses of pyridine and 2,2′-bipyridine in tetrahydrofuran gave the six-coordinate complexes FeX2(acac)(py)2and FeX2(acac)(bipy), respectively.
Diprotonated Bimetallic Complex between Copper(II) with 3,3′-Bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolsulfonphthalein
Authors: Yamada Mutsuo 
Published: July 2006

Abstract
The solution chemistry for complexes of copper(II) with 3,3′-bis[N,N-bis(carboxymethyl)aminomethyl]-o-cresolsulfonphthalein(XO) is studied by spectrophotometric measurement. Copper(II) is found to form a diprotonated bimetallic complex with XO in weakly acidic medium. Stability constant and molar absorptivity of the complex are evaluated to be logKCu2LH2=9.86±0.05 and ε574nm=3.73×104 M−1 cm−1, respectively, at 25.0 °C and I=0.1 M. Thermodynamic parameters are calculated to be ΔH=4.3 kcal·mol−1 and ΔS=64 eu at 25.0 °C and I=0.1 M.
Derivatographic Studies on Transition Metal Complexes. XVII. Solid-phase Deaquation-anation of Some Optically Active Aqua—cobalt(III) Complexes
Authors: Tsughiya Ryokichi , Omote Masakatsu , Uehara Akira , Kyuno Eishin 
Published: July 2006

Abstract
Stereochemical changes involved in the solid-phase deaquation-anation of the following optically active aqua-cobalt(III) complexes were investigated: (+)546-cis-[Co(H2O)2en2]X3·2H2O (X=Cl or Br), (+)589-cis-α[CoCl(H2O)en2]Cla·H2O, (−)589-cis-[CoCl(H2O)en2]Br2·H2O, (+)589-α-[CoCl(H2O)trien]Cl2·H2O and (+)589-α-[CoCl(H2O)trien]Br2·2H2O, where en and trien denote ethylenediamine and triethylenetetramine, respectively. Thermal deaquation-anation processes for each complex were observed with a derivatograph, polarimeter, and UV and CD spectrophotometers. cis-[Co(H2O)2en2]Cl3·2H2O was converted into cis-[CoCl(H2O)en2]Cl2 at first and then cis-[CoCl2en2]Cl; the stereochemical changes during the first step and the second step were found to be retention and racemization, respectively. In contrast, a predominant stereochemical change involved in the deaquation-anation of cis-[Co(H20)2en2]Br3·2H2O was cis-to-trans isomerization. The deaquation-anation of cis-[CoCl(H2O)en2]Cl2·H2O and cis-[CoCl(H2O)en2]Br2·2H2O was found to be accompanied by racemization and by greater parts of cis-to-trans isomerization, respectively. However, both α-[CoCl(H2O)trien]Cl2·H2O and α-[CoCl(H2O)trien]Br2·2H2O undergo deaquation-anation with retention.
A Convenient Synthesis of β-Acetyl-γ-substituted-γ-butyrolactones and γ-Acetyl-δ-substituted-δ-valerolactones
Authors: Sato Toshio , Hanna Junichi , Nakamura Hideo , Mukaiyama Teruaki 
Published: July 2006

Abstract
A convenient method for the preparation of β-acetyl-γ-substituted-γ-butyrolactones (III) and γ-acetyl-δ-substituted-δ-valerolactones (IV) is described. It was established that α-angelicalactone (I) and 3,4-dihydro-6-methyl-2H-pyran-2-one(II) react with various aldehydes in the presence of boron trifluoride etherate (BF3·OEt2) to afford the corresponding γ and δ-lactones, respectively, in good yields.
Hydrolysis of Carbohydrates in the Presence of a Reversed Micelle. I. Hydrolysis of Sucrose in a Dioxane–Water Mixed Solvent
Authors: Arai Kenichiro , Ogiwara Yoshitaka , Ebe Kazuyoshi 
Published: July 2006

Abstract
Formation of a reversed micelle by dodecybenzenesulfonic acid (DBSH) in a dioxane–water mixed solvent was discussed in terms of the behavior of critical micelle concentration and NMR study. Hydrolysis of sucrose in the presence of the reversed micelle was then investigated. The pseudo-first-order rate constant of the reaction showed a tendency to increase with decreasing substrate concentration and increasing dioxane composition, and the maximum rate acceleration obtained in the present experiment was 21-fold on the basis of the reaction in aqueous solution. The rate acceleration may result from the solvent effect of dioxane relating to the structuredness of water and the substrate binding effect due to the formation of the reversed micelle.
Studies of Unusual Amino Acids and Their Peptides. VI. The Syntheses and the Optical Resolutions of β-Methylphenylalanine and Its Dipeptide Present in Bottromycin
Authors: Kataoka Yoshiharu , Seto Yasuhiko , Yamamoto Masaaki , Yamada Takashi , Kuwata Shigeru , Watanabe Hiroshi 
Published: July 2006

Abstract
β-Methyl-phenylalanine was prepared by the condensation of α-methylbenzyl bromide with acetaminomalonate, followed by the hydrolysis and decarboxylation of the condensate. The decarboxylation occurred diastereoselectively to some extent. The erythro and the threo isomers could be separated by the fractional crystallization of their benzoyl derivatives, and differentiated by means of their NMR spectra. The optical resolution of the respective isomers was attained by treating the benzyloxycarbonyl derivatives with qunine or quinidine; thus, the four isomers could be obtained in a pure state. A dipeptide present in the C-terminal of bottromycin was synthesized by coupling N-protected erythro-l-β-methyl-phenylalanine with either l-β-(2-thiazolyl)-β-alanine ester or, more conveniently, with the Dl-compound, and by separating thereafter.