Yoshio Kosugi

Linear free energy relationships for carbon-13 NMR chemical shifts of substituted benzoic acids1

Abstract In order to examine 13C-SCS of substituted benzoic acids, chemical shifts of the acid form (I) and the dissociated form (II) have been obtained separately. Single substituent parameters, σ0 or σ+ are correlated with the shifts for the carboxyl (δco) or ipso carbons (δipso), respectively. Among the available five equations which are developed for the analysis with dual (or divided) substituent parameters (DSP), the Swain-Lupton equation (eqn 3) and the Taft-Swain-Lupton equation (eqn 4) give much better correlations, not only for δco and δipso but also for the results for ring carbons (C(2), C(5), C(6)), except for those attached to or neighboured by substituents. It is concluded that the SCS of aromatic compounds are best analyzed with substituent parameters derived from reactions or equilibria on the basis of linear free energy relationships.

Unusually large protonation shifts of aromatic carboxylic acids in carbon-13 nuclear magnetic resonance

Abstract Unusually large protonation shifts in carbon-13 NMR spectra of benzoic acid and phthalic, isophthalic, and terephthalic acids are observed. These chemical shift changes of δ co and δ ipso are 11 to 12 and 8 to 10 ppm (downfield shifts on the deprotonation), respectively. The protonation shifts are discussed in terms of electric field shift theory, polarity effect, and anisotropic effect. The effect of hydrogen-bond formation in the dimeric form of benzoic acid on the chemical shift of carboxyl carbon is estimated to be 4.9 ppm.

Studies on Inclusion Behaviors of β-Cyclodextrin-Starch Composite Gel by Spin Probe Method

Abstract A composite gel prepared from β-cyclodextrin and starch in a 1:2 ratio and cross-linked by epichlorohydrin was used as a host compound for inclusions. The competitive inclusion between 4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy and chloro-substituted acetic acids was monitored by ESR spectroscopy. The triplet signals enabled us to estimate the rotational correlation frequencies of the radical by employing Kivelsons equation. The unusual temperature dependence of the frequencies suggests that gradual loosening of the gel link occurs with an increase of temperature from 30 to 60°c, resulting in increased amounts of the inclusion which cancels the increments of the correlation frequencies. The gel is found to be a better host than β-cyclodextrin for dichloro, monochloro, and un-substituted acetic acids, at least below 50°c. Trichloroacetic acid is included in the gel as much as is dichloroacetic acid, but much more than monochloroacetic acid and acetic acid, which still compete comparably with ...

Analysis of sodium alkylsulphonates using filament heated in-beam electron impact mass spectrometry

ZusammenfassungMit Hilfe dieser Methode (280–450° C) erhält man für Natriumalkylsulfonate (RSO3Na mit R=C2H5 bis n-C12H25) sehr einfache Massenspektren: Na+, [RSO3Na2]+ (Basispeak mit Ausnahme von R=n-C4H9), [(RSO3)2Na3]+ und in den meisten Fällen [(RSO3)3Na4]+. Andere Fragmentierungen als diese 3 oder 4 Peaks wurden nur bei n-Heptylsulfonat beobachtet. Dieses Verfahren zur Analyse einfacher Alkylsulfonsäuren ist für übliche Elektronenstoß-Massenspektrometer verwendbar.SummaryBy means of the filament heated in-beam method at 280–450° C, the series of sodium alkylsulphonates (RSO3Na, where R=C2H5 to n-C12H25) give very simple mass spectra: Na+, [RSO3Na2]+, which is the base peak except for R=n-C4H9, [(RSO3)2Na3]+ and, in most cases, [(RSO3)3Na4]+. Fragmentations other than these three or four peaks are observed only in the case of n-heptylsulphonate. The proposed method of analysis for simple alkylsulphonic acids is applicable to ordinary electron-impact mass spectrometers.

Mass spectra of alkylbenzenesulphonates by filament heated in-beam electron impact

ZusammenfassungMit Hilfe der vorgeschlagenen Technik ergeben Natriumbenzolsulfonate einen starken Dinatriumsulfonatpeak sowie Clusterionen von Tri- und Tetranatriumsulfonaten. Natriumdodecylbenzolsulfonate ergeben ebenfalls Molekular- und Natriumionenpeaks und klare Fragmentierungsmuster, die denen der entsprechenden Kohlenwasserstoffe vergleichbar sind. Nach den erhaltenen Resultaten können »harte« und »weiche« Alkylbenzolsulfonate voneinander unterschieden werden.SummarySodium benzenesulphonate gives a strong disodium sulphonate ion peak and cluster ions of tri- and tetrasodium sulphonates by our devised EI-MS. Sodium dodecylbenzenesulphonates also give molecular plus sodium ion peaks and clear fragmentation patterns comparable with those of corresponding hydrocarbons. The results suggest that hard-type and soft-type alkylbenzene sulphonates (ABS) can be differentiated from each other.

Structures of phenol red

To our surprise we found [1] that NMR spectrometry has disclosed the fallacy of quinone-phenolate theory which had been long accepted for red colour of phenolphthalein 1. It is interesting to examine the structurally similar phenol red 2 which is another typical acid-base indicator. We wish to present here similarities and differences between 1 and 2 based on proton and carbon-13 NMR spectra. These data are also an extention of our NMR analyses of organic sulphonic acids [2, 3].

Bestimmung der relativen Stabilitäten der Zink- und Eisenkomplexe von 5-Chlor-7-iod-8-hydroxychinolin (Chinoform) durch KMR-Spektroskopie

Die Ligandenaustauschreaktionen des Chinoforms wurden mit Hilfe der KMR-Spektroskopie untersucht. In Hexamethylphosphorsauretriamid und Dioxan sind die Zink- und Eisen(III)-komplexe des Chinoforms stabiler als die entsprechenden Oxinate. Der 7-Iod-Substituent des Chinoforms reagiert vermutlich direkt mit den Metallionen.ZusammenfassungDie Ligandenaustauschreaktionen des Chinoforms wurden mit Hilfe der KMR-Spektroskopie untersucht. In Hexamethylphosphorsäuretriamid und Dioxan sind die Zink- und Eisen(III)-komplexe des Chinoforms stabiler als die entsprechenden Oxinate. Der 7-Iod-Substituent des Chinoforms reagiert vermutlich direkt mit den Metallionen.SummaryLigand exchange reactions associated with chinoform which is implicated in SMON have been investigated by proton NMR. Zinc and iron(III) complexes of chinoform are proved to be more stable than the corresponding oxinates in hexamethylphosphoric triamide or dioxane. The 7-iodo substituent of chinoform is supposed to interact directly with the metal ions.

Nuclear magnetic resonance spectra of 8-hydroxyquinolines and their zinc chelates in hexamethylphosphoric triamide

ZusammenfassungZink-, Mangan- und Chromchelate von 8-Hydroxychinolin lösen sich leicht in Hexamethylphosphortriamid. Ungefähr 3%ige Lösungen der Zinkkomplexe von 8-Hydroxychinolin und dessen 5-Sulfonsäurederivat ergeben gut aufgelöste 1H-KMR-Spektren. Die Ergebnisse der Untersuchungen sind nicht nur für die Interpretation komplizierter Oxinspektren, sondern auch für die Bestimmung der Struktur und relativen Stabilität von Chelation-Verbidnungen von Nutzen.SummaryZinc, manganese and chromium chelates of 8-hydroxyquinoline have been found to dissolve in hexamethylphosphoric triamide easily. Ca. 3% solutions of zinc complexes of 8-hydroxyquinoline and its 5-sulphonic acid derivative give well resolved 1H NMR spectra. The results are useful not only for interpretation of intricate spectra of 8-hydroxyquinolines but also for determination of structures and relative stabilities of chelation compounds.

NMR spectroscopic studies on the relative coordination ability of thiooxine

ZusammenfassungDie Protonen-KMR-Spektren von Thiooxin wurden untersucht. Bei der Bildung von Zinkthiooxinat wurde ein Shift von −0,2 ppm für H2 und von +0,36 ppm für H4 beobachtet. Die relative Koordinationsfähigkeit in Hexamethylphosphorsäuretriamid wurde mit Hilfe der KMR durch Ligandenaustausch und kompetitive Koordination untersucht. Die Ergebnisse zeigen, daß die Bindung des Zinks an Thiooxin stärker ist als an Oxin; bei Magnesium ist sie schwächer als an Acetylaceton.SummaryProton NMR spectra of thiooxine are analyzed. Upon formation of zinc thiooxinate, an upfield shift (−0.2ppm) of H2 and a downfield shift (+0.36ppm) of H4 are observed. Relative coordination ability in hexamethylphosphoric triamide is examined by ligand exchange reaction or competitive coordination reaction monitored by NMR method. The results indicate that thiooxine coordinates to zinc stronger than oxine does, but to magnesium weaker than acetylacetone does.