Millimeter-wave spectrum of 3-butynenitrile: Dipole moment and centrifugal distortion constants

The molecular rotational spectrum of 3-butynenitrile (3BN, propargyl cyanide), HCCCH₂CN, has been investigated in the vibrational ground state. A total of 222 transitions up to J = 69 have been measured between 8 and 300 GHz. The Hamiltonian used for the spectral analysis was required to include all centrifugal terms of fourth and sixth orders and one term of eighth order in the angular momentum components in order to reproduce the transition frequencies within the experimental error. Significant values for the respective distortion coefficients could be determined. The molecular dipole moment components were calculated from measured Stark effect shifts as |μ_a| = (3.23 ± 0.05) D, |μ_b| = (2.34 ± 0.02) D; μ_tot = (3.99 ± 0.05) D.     

Synthesen von Heterocyclen, 120. Mitt.: 2,6-Dimethyl-4-pyridone durch Reaktion von Enaminen mit Diketen

Zusammenfassung Primäre und sekundäre Enaminderivate aus Acetessigester und -Diketonen reagieren beim Erhitzen mit Diketen zu Derivaten des -Pyridons.

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Syntheses of heterocycles, CXX: Synthesis of 2,6-dimethyl-4-pyridones from enamines and diketene

Primary and secondary enamines derived from ethyl acetoacetate or -diketones react with diketene to yield -pyridones.

     

Analysis of methylisothiazolones by ion pair high-performance liquid chromatography after pre-column derivatisation

Summary 2-Methyl-3(2H)-isothiazolone resp. 5-chloro-2-methyl-3(2H)-isothiazolone were isolated from a commercial methylisothiazolone formulation (Kathon CG) by flash chromatography and subsequently converted into the respective-thio-substituted acrylamide derivative with the help of the nucleophilic reagent hydrogensulfite. UV spectra and absorption characteristics, for both the derivates as well as the original methylisothiazolones are given and represented in comparison. The derivatives differ clearly in their absorption characteristics from the reactants. Especially in case of the non-chlorinated constituent, derivatisation leads to a distinct increase of its UV activity. For separation and quantification of the derivates an ion pair high-performance liquid Chromatographic method had been developed. With this method an independent system for verification of the content of methylisothiazolones, determined in conventional analysis, is available.

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Analytik von Methylisothiazolonen durch Ionenpaar-HPLC nach Vorsäulen-DerivatisierungTeil I. Derivatisierung von 2-Methyl-3(2H)-isothiazolon und 5-Chlor-2-methyl-3(2H)-isothiazolon

     

Influence of complexation phenomena with multivalent cations on the analysis of glyphosate and aminomethyl phosphonic acid in water

Experimental and theoretical influence of multivalent cations on the analysis of glyphosate and aminomethyl phosphonic acid (AMPA) was studied in pure water and in one surface water. The procedure chosen, based on derivatization with FMOC-Cl, HPLC separation, and fluorescence detection, appears highly affected at cations concentrations current in natural waters. A detailed speciation study performed with the VMINTEQ software strongly suggests that the complexes formed between analytes and cations do not dissociate during the reaction and do not react with the derivatization agent, so that only the free forms are derivatized. These results point out the necessity of a pre-treatment to prevent these interferences, even in low salinity waters. The different ways conceivable are discussed in terms of kinetic and thermodynamic considerations.