Showing papers in "Bulletin of the Chemical Society of Japan in 1965"

A New Method of Analyzing Thermogravimetric Data

Abstract: A new method of obtaining the kinetic parameters from thermogravimetric curves has been proposed. The method is simple and applicable to reactions which can not be analyzed by other methods. The effect of the heating rate on thermogravimetric curves has been elucidated, and the master curve of the experimental curves at different heating rates has been derived. The applications of the method to the pyrolyses of calcium oxalate and nylon 6 have been shown ; the results are in good agreement with the reported values. The applicability of the method to other types of thermal analyses has been discussed, and the method of the conversion of the data to other conditions of temperature change has been suggested. From these discussions, the definition of the thermal stability of materials has been criticized.

Estimation of Anharmonic Potential Constants. I. Linear XY2 Molecules

Abstract: On the basis of a normal-coordinate analysis of a series expansion of the anharmonic potential field, a set of general expressions has been derived for a linear XY2 molecule for relating the cubic and quartic potential constants (k) to the coefficients (f) of the potential function expanded in terms of the internal coordinates. The constants k and f for CO2 and CS2 have been calculated by using the observed values of α and x taken from the literature, and the physical significance of the dependence of k on f has been studied.The anharmonic constants related to the C-O(C-S) bond-stretching vibrations are represented as functions of the parameters of anharmonicity, a3 and a4, which are shown to be transferable from the CO(CS) diatomic molecule. Most of the k, α, and x values for CO2 and CS2 can be predicted quantitatively by assuming a simple potential function, comprised of ordinary quadratic terms and the anharmonic terms for the bond-stretching vibrations mentioned above, with all other higher-order pote...

The Electronic Spectra of Pyrene, Chrysene, Azulene, Coronene and Tetracene Crystals

Abstract: The electronic absorption spectra of single crystals of pyrene, chrysene, azulene, coronene and tetracene have been measured by a polarized light. Some crystal absorption bands exhibit appreciable splittings and changes in intensity relations according to the simple exciton theory. Those results are explained by the use of the second-order exciton calculation without the inclusion of the electron overlap effect. The theoretical results give a fairly reasonable explanation of crystal spectra, and it has been shown that the second-order mixing of excited states plays an essential role in modifying the crystal spectra from the pattern of the free molecule.

Phase Transitions in Crystalline Divalent Metal Dicalcium Propionates. I. Calorimetric and Dielectric Investigations of Strontium- and Lead Dicalcium Propionates

Abstract: Heat capacities have been measured for strontium and lead dicalcium propionates from 15 to 300°K with an adiabatic-type calorimeter in connection with the ferroelectric phase transition of strontium salt. The heat capacities, enthalpies, entropies and Gibbs energy functions in the standard state have been determined. For the strontium salt, the transition temperature, the heat of transition, and the entropy of transition for the ferroelectric phase transition are 282.6°K, 159.6 cal.mol−1, and 0.6 e.u. respectively. Another phase transition was discovered at 104°K; the heat and entropy of this transition amount to 255 cal.mol−1 and 3.2e.u. respectively. For the lead salt, a phase transition was found at 191.5°K, and the heat and the entropy of the transition are 1160.0 cal. mol−1 and 5.8 e.u. respectively. Low frequency dielectric constants have been measured for the lead salt from the liquid nitrogen temperature to 90°C. A discontinuous change in the dielectric constants at 183°K and another dielectric an...

Thermodynamic Properties and Order-Disorder Phase Transitions of the Potassium Cyanide Crystal

Abstract: The heat capacities of the potassium cyanide crystal have been measured over the temperature range from 13 to 310°K by using a low temperature adiabatic calorimeter It has been found that there are two regions of anomalous heat capacity, with maxima at 829±02°K and 1683±01°K respectively The heats and entropies of transition have been evaluated by utilizing a ΘD-versus-temperature plot The entropy of the lower transition amounts to about R ln 2, which means that the transition is due to the orientational order-disorder rearrangement of the cyanide ion with respect to its head and tail A perfectly-ordered structure for the orientation of the cyanide ions has been suggested A certain small anomaly in heat capacity has been found around 190°K, one which seems to be associated with some change in higher-order structural defects created by the upper transition phenomenonThe torsion-rotational heat capacity of the cyanide ions has been separated from the total on some reasonable assumptions The resul

The Trifluoroacetate Method of Peptide Synthesis. I. The Synthesis and Use of Trifluoroacetate Reagents

Abstract: The trifluoroacetates of various phenol, thiophenol and N-hydroxyimide derivatives, which are known as hydroxylic partners of various active carboxylic acid ester, have been synthesized, and it has been found that they are good reagents for the preparation of the respective active esters of acylamino acids by the ester-exchange reaction in pyridine The new method is especially effective in the preparation of p-nitrophenyl, 2,4,5-trichlorophenyl and N-hydroxysuccinimide esters of acylamino acids, which are well known to be useful intermediates for peptide synthesis The direct syntheses of peptides using these reagents, without the isolation of the intermediates, have been studied, and the new procedure has been found to be wise elongation of peptides

A Synthesis of Oxytocin

Abstract: N-Carbobenzoxy-S-methoxybenzyl-L-cysteinyl-L-tyrosyl-L-isoleucyl-L-glutaminyl-L-asparagin-yl-S-p-methoxybenzyl-L-cysteinyl-L-prolyl-L-leucylglycinamide (IX) was synthesized by the step-wise elongation method, and highly potent oxytocin was obtained from IX by treatment not only with sodium in liquid ammonia, but also with boiling trifluoroacetic acid, followed by the usual aeration procedure. It was demonstrated during the reactions that the newly introduced S-p-methoxybenzyl group could be cleaved more easily than the usual S-benzyl group, and that the new S-protecting group was useful in the preparation of complicated cysteinyl peptides.

An Automatic Adiabatic Calorimeter for Low Temperatures. The Heat Capacity of Standard Benzoic Acid

Abstract: An adiabatic calorimeter for the measurements of the heat capacity of a solid and liquid over the temperature range from 13 to 300°K has been constructed. In order to minimize the operating manpower, all the temperature controls were recorded semiautomatically. The energy input was started and stopped automatically by a timer driven by a signal from a transistor clock. The working platinum resistance thermometer was calibrated against a laboratory standard thermometer which had been calibrated by the National Bureau of Standards. In order to verify the performance and the accuracy of this one-man-operated calorimeter, the heat capacity of a Calorimetry Conference Standard sample of benzoic acid crystal has been measured from 15 to 310°K. The results have compared with the data from the NBS and from other laboratories; this comparison served to establish the reliability of this equipment. The estimated errors are ±2% at 20°K, ±1% below 50°K, and ±0.3% above 50°K.

Studies of Ion Exchange Membranes. XXII. Semicontinuous Preparation of Ion Exchange Membranes by the “Paste Method”

Abstract: A method for the preparation of ion exchange membranes called the “paste method” has been developed into a semicontinuous preparation. The roll-coating system being employed, a base membrane 1 m. wide and 50 m. long is prepared continuously; the ion exchange group is then introduced to it. The ion exchange membranes thus prepared have been proved to have excellent electrochemical and mechanical properties as well as an excellent appearance.

Switch-over of the Mechanism of the Primary Processes in the Photo-oxidation of Xanthene Dyes as Revealed by the Oxygen Consumption Experiments

Abstract: The oxygen up-take of irradiated aqueous solutions of xanthene dyes has been investigated by means of Warburg’s apparatus, and evidence for a switch-over from a D–O to a D–D mechanism is obtained from the variation of dye-concentration. This view is supported by the photobleaching rate and the oxygen concentration effect at high eosine concentrations (∼10−4M).The quautum yields (γo2) of the consumption are estimated and it is found that γo2(D–D) is larger than γo2(D–O).

Vibration-Rotation Spectra, the Coriolis Coupling Constants and the Intramolecular Force Field of Symmetric Top Molecules. I. The E-type Fundamental Bands of Methyl and Methyl-d3 Halides

Abstract: The infrared spectra of CH3X and CD3X (X=Cl, Br and I) have been observed with a high-resolution instrument in the region 500–3300 cm−1. The rotational fine structures of all the E-type fundamental bands have been resolved and analyzed, giving the Coriolis coupling constants, the rotational constants and the frequencies of the band origins. The uncertainties of the observed molecular constants have been discussed. On the basis of the observed data for the rotational constants and their changes by the excitation of vibration, the structures of methyl halide molecules have been determined.

Organic Photochemical Reactions. I. The Synthesis of Substituted Oxetanes by the Photoaddition of Aldehydes to Furans

Abstract: The photochemical reaction of aldehydes (propionaldehyde and benzaldehyde) and furan have been studied in the liquid phase; two new compounds, oxetanes I and II have easily been produced with a high purity by this photo-reaction. In the case of 2-methylfuran and propionaldehyde (or benzaldehyde), a mixture of oxetanes III and IV (or V and VI) has also been obtained.

The formylation of amino acids with acetic formic anhydride.

Abstract: The formylation of amino acids with acetic formic anhydride has been studied. This anhydride is prepared by the reaction of acetyl chloride with sodium formate or, preferably, from ketene and formi...

The Structure and Stereochemistry of Four New Sesquiterpenes Isolated from the Wood Oil of “Kaya” (Torreya nucifera)

Abstract: Four new sesquiterpenes, nuciferal (II), nuciferol (III), torreyal (IV) and neotorreyol (V), together with dendrolasin and o-methoxycinnamic aldehyde, have been isolated from the neutral volatile wood oil of Kaya (Torreya nucifera Sieb. et Zucc.) by adsorption chromatography on silica gel. The structures and stereochemistry of these new compounds have been confirmed by infrared, ultraviolet, NMR and MS spectrometry, as well as by chemical methods.

The Rotatory Dispersion of Cobalt(III) Ammine Complexes Containing Amino Acid as a Unidentate Ligand

Abstract: Fifteen new cobalt(III) ammine complexes containing amino acids as unidentate ligands have been prepared. The infrared, visible and ultraviolet absorption spectra of these complexes indicate that the oxygen of the carboxyl group acts as a donor atom. The circular dichroism and the rotatory dispersion of the unidentate complexes of the optically active α-amino acids and such chelate amino acid complexes as [Co(L-α-ala) (NH3)4]2+ have been measured. The results suggest that the magnitude of the anomalous dispersion of the α-amino acid complex in the region of its first absorption band seems to depend mainly on the conformational mobility of the optically active ligand in the coordination sphere.

Semi-empirical Self-consistent Field Molecular Orbital Calculation of the Electronic Structure of the Base Components of Nucleic Acids

Abstract: SCF MO calculations have been carried out for adenine, guanine, thymine, cytosine, uracil, 9-methyladenine and 1-methylthymine. In evaluating the two-center repulsion integral, the Pariser-Parr and Mataga-Nishimoto approximations have both been used, and the results compared with each other and with the experimental data on the optical properties. In the calculation of thymine, 9-methyladenine, and 1-methylthymine, the hyperconjugation of the methyl group has been taken into account. The calculated wavelength and the oscillator strength of the singlet-singlet transition for the above-mentioned molecules explain the experimental values well except for thymine and 1-methylthymine. The theoretically determined directions of the polarization of the transition moments have been compared with the experimental results for adenine, 9-methyladenine and 1-methylthymine. With regard to the direction of the polarization of the transition moments of the first and the second absorptions of adenine and 9-methyladenine, ...

Phase Transition in the Ammonium Bromide Crystal: The Thermal Motion of the Ammonium Ion

Abstract: We have measured the heat capacities of the ammonium bromide crystal from 13°K to 305 °K and have found two phase transitions in this temperature region. From the results, the heat and entropy of transitions at the transition points, 107.5°K and 235.0°K, have been derived: for the lower transition, ΔHtr=29.29 cal. mol.−1 and ΔStr=0.271 cal. deg−1·mol−1; for the upper one, ΔHtr=156.1 cal.·mol−1 and ΔStr=0.714 cal. deg−1 mol−1. The values of the entropy and enthalpy function at 298.15°K are: S°=26.97 cal. deg−1 mol−1 and (H°–H°O)⁄T=13.56 cal. deg−1 mol−1. The torsional motions of the ammonium ions may well be represented in terms of a periodic potential function at the lowest temperature modification. The torsional frequency, 340±7 cm−1, and the potential barrier height, 4.00±0.16 kcal.mol−1, as determined on the basis of the thermal data, agree well with the values obtained in other experiments.The infrared spectra of thin, non-scattering films of ammonium bromide have been obtained at 298°K, 100°K, 88°K, ...

Photoelectric Emission and Electrical Conductivity of the Cesium Complex with Pyrene Derivatives

Abstract: On the basis o the charge transfer process of the complexes, the photoemission and the electronic conduction of the complexes between cesium and pyrene derivatives, tetranitropyrene (TNO2P), tetrachloropyrene (TClP), tetrabromopyrene (TBrP) and tetracyanopyrene (TCNP) have been measured. A strong increase in the quantum yield of photoemission, from 10−3–10−4 to 10−1–102, resulting from the formation of the complexes, has been found. The promotion may take place by means of an electron transfer from cesium metal to a partner molecule; [Cs+] [Aromatics−]. The assumption is supported by the findings concerning electron spin resonance absorption and charge-transfer spectra. The electrical resistivity of the complexes, ρ at 15°C of pyrene-Cs=2.1×104 Ωcm., (TClP)-Cs=8Ωcm., (TBrP)-Cs=1.6×101 Ωcm., (TNO2P)-Cs=2×106 Ωcm. and (TCNP)-Cs=6×105 Ωcm., is strongly affected by the contribution of the, dative-bond character of the complexes.

Metal Complexes of Amino Acids. I. The Circular Dichroism of Copper(II) Complexes with Optically Active Amino Acids

Abstract: On the basis of the CD measurements of the complexes of the [Cu(L-am)2] type, four CD components have been observed in the region of the d→d absorption band, namely, (+), (+), (−) and (−), listing from longer to shorter wavelengths. The L-configuration of the amino acids determines the signs of these CD components. Judging from the CD curves of the copper-(II) complexes with L-threonine and with L-allothreonine, it has been suggested that the vicinal effect caused by the α-asymmetric carbon atom is stronger than that caused by the β-asymmetric one. It has also been suggested that, when L-proline or L-hydroxyproline is coordinated to copper, the nitrogen atoms of these ligands are activated by the configurational stereo specificity.

Studies of the Liquid-Liquid Partition Systems. IV. The Solvent Extraction Study of Europium(III) Adduct Chelate Complexes with Six Acetylacetone Derivatives and Tributylphosphate

Abstract: The extraction of europium(III) in 0.1 M sodium perchlorate with acetylacetone, benzoylacetone, trifluoroacetylacetone, benzoyltrifluoroacetone, froyltrifluoroacetone and thenoyltrifluoroacetone in...

Mean-Square Amplitudes and Force Constants of Tetrahedral Molecules. II. Silicon Tetrachloride

Abstract: The atomic distances and the mean-square amplitudes of silicon tetrachloride have been determined by the sector-microphotometer method. The possible sources of experimental errors have been thoroughly examined. The quadratic force constants of the potential function have been determined by the use of the mean-square amplitudes thus obtained, by combining them with the vibrational frequencies obtained from the Raman spectrum in the gaseous state. It has been shown that the errors of the force constants originate from those of the mean-square amplitudes by the same order of magnitude as from those of the frequencies.

A Molecular Orbital Treatment of Hydrogen Bonds. I. Preliminary Results

Abstract: 1) The changes caused by hydrogen bonds in the electronic structure of several molecules have been discussed by the use of the extended LCAO MO method. 2) The delocalization energy have been calculated to be 3.8 kcal./mol. 3) The frequency shifts in the ultraviolet spectrum cannot be explained. 4) In the formic acid dimer it has clearly been shown that the population transfers from the carbonyl group to the hydroxyl group and that a small bond population arises between them. 5) The 2pπ orbital on the hydrogen atom contributes almost nothing to the π delocalization energy. 6) The π hydrogen bond has also been discussed. 7) The defects in the extended LCAO MO method in treating molecules with polar groups or lone pairs have been pointed out, a method for improvement suggested, and some critical discussion of the present treatment added. The calculation was carried out on the IBM 7090 at the Japan IBM Co., with the permission of the UNICON Committee, whose kindnees we hereby acknowledge.