Electrophoretic clean-up of organic acids from coffee for the GC/MS analysis

The clean-up presented here includes a free flow field step electrophoresis followed by ultrafiltration. Thus, organic acids can be separated from non-acidic and high-molecular compounds in roasted and instant coffee. The acids are identified by gas chromatography/mass spectrometry after freeze-drying and trimethylsilylation. With the method presented, 31 acids could be identified in commercial roasted coffee blends and in instant coffee, among them for the first time in coffee: 3-hydroxypropionic, 2-oxobutyric, glyceric, 2,4-dihydroxybutyric, 5-hydroxymethylfuran-2-carboxylic and 2-hydroxyglutaric acid.     

Measurement of np elastic scattering at high energies and very small momentum transfers

The np elastic differential cross section has been measured for incident neutron momenta 100–400 GeV/c in the |t| range 6 · 10^?6 ? 5 · 10^?1 (GeV/c)². The np data of this experiment provide a first direct measurement of the hadronic amplitude for |t| < 10^?2 (GeV/c)², which is consistent with the extrapolations from higher |t| values. Our data for |t| < 10^?4 (GeV/c)² are consistent with a rise which can be attributed to Schwinger scattering, caused by the interaction of the neutron magnetic moment with the proton.     

Hetero-diels-alder reactions of α-methoxymethylene substituted 1.3-dicarbonyl compounds with enol and enediol ethers

The inverse electron demand hetero-Diels-Alder reaction of methoxymethylene substituted 1.3-dicarbonyl compounds with enol ethers and enediol ethers results in the selective formation of 3.4-dihydro-2H-pyrans. These adducts with a high density of functional groups are versatile intermediates for natural product syntheses.     

The Cyclobutadiene Problem

Cyclobutadiene has recently become the center of reawakened interest. By use of the matrix isolation technique, cyclobutadienes can now be prepared as monomers frozen in matrices. Thus both the unsubstituted parent compound and its alkyl-substituted derivatives are amenable to study. The present progress report surveys the entire field; however, particular emphasis is placed on the author's own results from investigations concerning this classical problem of organic chemistry.     

Orthogonene

Orthogonene is a symmetrical polycyclic olefin with a highly twisted double bond. Semiempirical calculations predict the orthogonal structure to be lower in energy than the twisted form which makes it the first symmetrically substituted orthogonal olefin.     

Niederenergetische Gammalinien vom Neutroneneinfang in Lu 175 und Lu 176

The low energy gamma-rays from neutron-capture in Lu 175 and Lu 176 have been investigated by means of the bent crystal-spectrometer at the DR-3-reactor at Risø. From the transitions in Lu 177 3 rotational bands have been determined. The levels of the (404)K=7/2⁺ groundstate rotational band are: 121,62 keV (I=9/2), 268,79keV (I=11/2), 440,66 keV (I=13/2), 636,22 keV (I=15/2), 854,34 keV (I=17/2). The level-sequence of the (514)K=9/2^?-band is: 150,39 keV (I=9/2), 288,99 keV (I=11/2), 451,49 keV (I=13/2), 637,05 keV (I=15/2) and 844,88 keV (I=17/2). At 457,92 keV is the basis for the (402)K=5/2⁺-band the higher levels of which are 552,05 keV (I=7/2), 671,89 keV (I=9/2), 816,63 keV (I=11/2), 985,23 keV (I=13/2), 1176,73keV (I=15/2) and probably 1389,5 keV (I=17/2). The energies of the levels apart from the 1389 keV-level have an accuracy of 7×10^?5. The energy differences between the 3 bands agree very well with the values expected from the Bohr-Mottelson-formulaE=A·I(I+1)+B·I ²(I+1)². The calculated branching-ratios within the 3 bands are in fairly good agreement with the experimental values. Theg _K -factors have been determined for 2 bands: It was found that for the (514)-bandg _K =1,16±0,04 and for the (402)-bandg _K =1,33±0,07.     

Synthesen von Heterocyclen

Zusammenfassung Analog dem Malonsäure-bis-(2,6-dimethylphenol)-ester¹ läßt sich auch der entsprechende n-Butylmalonsäureester unter Wanderung einer Methylgruppe cyclisieren. Unter dem Einfluß von AlCl₃ entsteht in diesem Falle vorwiegend 3-Butyl-6,8-dimethyl-4-hydroxycumarin II.