Band 27, Heft 6

The synthesis of the dihalogeno-tris-(4-dimethylamino-phenyl)-compounds Ar 2 EX 2 (E = P, As, Sb; X = Cl, Br, J and E = Sb, X = F; E = Bi, X = Cl) is described. A generally valid correlation between the chemical shift of the n.m.r. signal of an atom and the atomic parameters electronegativity and principal quantum number of valence electrons is deduced.

The synthesis of a new type of organometallic compounds with a group VB element and the composition Ar 3 E 2+ (Ar = 4-dimethylamino-phenyl; E = As, Sb) in which this element has the oxidation state +5 and the coordination number 3 is reported. In accordance with the electronic and n.m.r. spectra it is assumed that the electronic structure of these intensive blue cations is similar to that of the isoelectronic cation of crystal violet.

Isotropic g factors and hyperfine coupling constants of a series of complexes [Fe (NO) 2 (EZ 3 ) X] are reported. In accord with theoretical suggestions, the g factors arrange the ligands EZ 3 corresponding to their π acceptor abilities. Both donor and acceptor properties of the ligands exhibit considerable influence on the spin densities.

The preparation of salts or complexes of N-hydroxy urea with Na + , Li + , Mg 2+ , VO 2+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ und Pt 2+ is reported. Their i.r.-spectra and the n.m.r.-spectra of the ligand and its alkali salts as well as of the methylated and deuterated derivative are discussed. Finally lhe complex stability constants of Mn 2+ , Co 2+ , Ni 2+ , Cu 2+ and Zn 2+ compounds are measured and discussed.

By UV-spectrophotometric titrations and a mathematical analysis of the titration results the complex formation between polymolybdate and periodic acid was investigated. In the studied concentration range the following two heteropolyanions were identified: [JMo 6 O 24 ] 5– and [J 2 Mo 2 O 15 ] 4– As reported by H. COPAUX 1 in 1913 and later by G. JANDER et al. 2 the salts of the heteropolyacids are characterised by strong light absorption in the UV in contrast to the acids from which these salts have been prepared. Therefore the UV-spectroscopy is suitable for studying the formation of heterocomplex compounds.

Substituted amides react with tridiloromethanesulfenyl chloride in the presence of triethylamine to following compounds: S=PCl 2 NCH 3 SCCl 3 , S=PFCl 2 NCH 3 SCCl 3 , S =PFClNCH 3 SCCl 3 , S=PF 2 NCH 3 SCCl 3 , O = PCl 2 NCH 3 SCCl 3 , O= PFClNCH 3 SCCl 3 , O = PF 2 NCH 3 SCCl 3 , FSO 2 NCH 3 SCCl 3 and CF 3 SO 2 -NCH 3 SCCl 3 . The properties of these substances are described. They were characteriszed by elemental analyses, IR- and mass spectra. 19 F-, 1 H- and 31 P-NMR spectra are reported and discussed.

59 Co-nmr-spectroscopic investigations of solutions of the complexes [Co (NO) 2 X(PZ 3 )]* in CH 2 Cl lead to relations between the chemical shift τo and bonding parameters of the Co-X-bond and the Co-PZ 3 -bond, respectively. With decreasing chemical shift, covalency of the Co-X-bond is increasing in the order Cl<Br<J. Regarding the PZ 3 ligands, τCo is a measure of the π-acceptor ability of PZ 3 , which increases in the order PPh 3 ∼ PPh 2 Z ∼ PPhCl 2 < alkylphosphine ∼ phenylalkylphosphine ∼ phosphines containing NR 2 -groups < phosphines containing OR-groups. The different π-accetor abilities are explained by varying Z-P-interaction.

Dichloro-bis (isocyanide) -platium (II) co-ordination compounds with arylisocyanides exist in two different modifications. One of them has a columnar structure consisting of “pancaked” cis-PtCl 2 (CNR) 2 molecules. Optical criteria classify some of these compounds as onedimensional metals.

Triphenyl Phosphine Oxide (TPO) which is known as a strong inhibitor of electrode processes in aqueous solutions is progressively adsorbed at the dme from methanol in the potential range -0.5 to -1.3 volts as compared with water, -0.15 to -1.6 volts (Ag/AgCl), for the concentrations studied. Adsorption activity as well as the sharpness of the desorption peak of TPO decrease in the order: water > 50% methanol > methanol and the adsorption region contracts as the solvent is changed from water to methanol. Adsorption isotherms in methanol and 50% methanol follow Langmuir's equation with adsorption coefficients equal to 1.58 x 10 2 l/mole and 1.62 x 10 4 l/mole respectively.

Kinetic studies of the reaction between Ammonia and Chlorine were carried out and it was found to be of second order. The reaction was studied at 20 ± 0.1°C and below pH value of 5. Above this pH the reaction being very fast could not be measured. The ΔΕ (energy of activation) and AS (entropy of activation) values of this reaction were found to be 32.66 Kcal/mole and 10.23 cal/deg.mole respectively. The reactive species appears to be hypochlorite in this reaction.

The reaction between diironenneacarbonyl and three with respect to the positions of the methyl groups isomeric trans-3,4-dichloro-dimethyl-cyclobut-1-enes is studied. Two of these isomers yield the expected 1,2-dimethyl-cyclobutadiene-irontricarbonyl; from the reaction of the third isomer a new iron-organic compound is obtained, the structure of which is determined by spectroscopic and chemical methods.

UV-Photolysis (λ=254 nm) of 5-iodouracil in aqueous oxygenated solution in presence of ethanol, ethylene glycol and i-propanol was investigated at pH = 6. Isodialuric acid, uracil, H 2 O 2 and iodine were found in all solutions. In addition to the above products in presence of ethanol, ethylene glycol and i-propanol acetaldehyde, glycolaldehyde and acetone respectively were formed. The yields of these products were determined as a function of the alcohol concentrations. The results suggest that the primary step is a homolytic splitting of the C-I-bond forming a uracil radical and an iodine atom. The uracil radical reacts with oxygen to form isodialuric acid and with alcohols to give uracil and an alkylhydroxyradical. The ratio of the rate constants between the addition of oxygen and the H-atom abstraction of the uracil radical has been determined for the following H-donors: ethanol, ethylene glycol, i-propanol and glycerine (Table 1). The reactions of the alkylhydroxyradicals with oxygen give the corresponding aldehyde or ketone respectively and H 2 O 2 . In the absence of oxygen the UV-photolysis of iodouracil in the presence of i-propanol leads to uracil, acetone and iodide. Consideration of the material balance leads to a reaction scheme which explains all the final products.

Ascorbic acid is oxidized by the OH radical and by radical anion complexes X 2 ⁻ (X: Cl, Br, J, SCN) to yield the “ascorbic acid radical” which finally disappears by second order. The pK of this radical was found to be about 3. It has several precursor radicals formed by the addition of OH or X to ascorbic acid. They lose H 2 O or HX, respectively, with different rates or are desactivated in radical-radical reactions. The precursor radicals are acids of different pK values. Since ascorbic acid exists in two tautomeric forms in aqueous solution, two precursor radicals are postulated for the reaction of OH with ascorbic acid: They lose water or OH⁻ with different rates to form the ascorbic acid radical. The absorption spectra of these species were measured. All radicals including the ascorbic acid radical have strong absorption at 3600 A, although somewhat different extinction coefficients. The decay of the 3600 A absorption in the 100 μs and millisecond range, which in earlier work of BIELSKI et al. 3 has been attributed solely to the disappearance of the ascorbic acid radical is partly due to the loss of water of long-lived precursors and to radical-radical desactivation of precursors and the ascorbic acid radical. Earlier conclusions of BIELSKI et al. about the pK of the ascorbic acid radical and about its protonization cannot be confirmed taking into consideration the complex precursor reactions. The kinetics is strongly dependent on the dose below about 400 rad. The precursor radicals formed by the addition of X to ascorbic acid are generally shorter lived than the OH addition precursors.

Diethyl acylmalonates are decomposed during gas chromatographic analysis in the metallic injection port and metallic column. Qualitative and quantitative determination of the volatile fragments demonstrates different modes of cleavage. These fragments can be identified as: ethene, carbon dioxide, a methyl ketone, a β-keto acid ethyl ester, ethanol, diethyl malonate and a monocarboxylic ethyl ester.

The change of free enthalpy involved in intramolecular hydrogen bonding is smaller if the proton acceptor group can rotate round a single bond, as compared to proton acceptor groups which are fixed in a position optimal for hydrogen bonding. Also, the free enthalpy change is altered when the rotation of the proton acceptor is sterically restricted. This is demonstrated by comparing the absorptions of carbonyl stretching vibrations in the infrared spectra of certain compounds showing rotational isomerism. In the present study derivatives of 5-hydroxy-2,2-dimethyl-6-carbomethoxychromanone- (4), 3-nitrosalicylaldehyde and 3-nitro-2-hydroxy-acetophenones substituted in the position 5 and 6 are examined.

The synthesis of the following thioethers of 2-chloro-6-mercaptopurine is described: 2-chloro-6-[4-phenyl-imidazole-2-thio] purine; 2-chloro-6- [4-guanidopropyl-imidazole-2-thio] purine; 2-chloro-6-[4-t.butyl-thiazole-2-thio] purine; 2-chloro-6- [4-phenyl-thiazole-2-thio] purine; 2-chloro-6- [4-methylthiazole-2-thio] purine; 2-chloro-6- [4-carbethoxymethyl-thiazole-2-thio] purine; 2-chloro-6- [4-carboxamido-5-amino-thiazole-2-thio] purine; 2-chloro-6- [5-phenyl-thiadiazole (1,3,4) -2-thio] purine; 2-chloro-6- [5-t.butyl-thiadiazole (1,3,4) -2-thio] purine; 2-chloro-6- [tetrazole-5-thio] purine. The thioether bond of these compounds is cleaved by nucleophilic agents especially by mercaptanes under mild conditions. The compounds are not metabolized by ascites cells and preferentially bound to the cell surface. They are inhibitors of DNA-, RNA-, and proteinsynthesis and of proliferation of Ascites cells in a different degree; the ascites carcinoma of mice was not influenced. A possible mechanism of action of their metabolic effects is discussed.

Gel layers of crosslinked polyacrylamide with different porosities were synthesized and their properties compared. At high concentrations of bifunctional monomers macroporous gels were formed, one of which (total monomer concentration 14%, methylene-bis-acrylamide 40%) permitted even high molecular weight proteins (e. g. γ-globulins) to diffuse more readily than in 2 per cent agar or agarose gels. Different immunological techniques were modified for application with this polymer. It offers advantages especially with respect to porosity, storability and sample application for quantitative diffusion techniques.

Chelation reactions of the antimitotic drug, 6-amino-purine (adenine; abbr. ADN) with the metal ions: Be(II), Al(III), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Pb(II), and UO 2 (II) have been investigated in aqueous solution at 30° using Bjerrum-Calvin pH titration technique. The formation constants have been determined at various ionic concentrations, and have been extrapolated to zero ionic strength to get the thermodynamic values of the constants.

The uropygial gland fat from the kittiwake is a complex mixture of ester waxes. As acidic components mainly n-octanoic acid and 2-methyl-substituted fatty acids are found. Besides 2,6-, 2,3 and 2,10-dimethyl-substituted fatty acids could be detected. Among the alcoholic components n-, 2-methyl-, 2,6-, 2,8-, 2,10- and 2,12-dimethyl-substituted primary alkanols were observed. Chemotaxonomically the kittiwake should be placed between the puffin and the limicoles.

The uropygial gland fat from the common scoter (Melanitta nigra) is a mixture of ester waxes of which 2,4,6-trimethyl-octanoic and 2,4,6-trimethyl-nonanoic acid are shown to be the main compounds within the acidic components. Besides traces of 2,4-dimethyl-heptanoic and 4,6-dimethyloctanoic acid could be detected. The alcoholic components of the waxes are more complex and consist of n-alkanols (77,6%) with chain-length from C 14 — C 18 and of monomethyl-substituted primary alcohols with the same chain-length and branches in 2-, 4-, 8-, 12- and 14-position. Chemotaxonomically the common scoter differs from other birds of this tribe but has some relationship to the barnacle goose and to the red-breasted merganser.

LDH, SDH and G-6-PDH activities have been determined in Uromastix hardwickii which hibernates during winter. Protein concentration was found to be significantly higher in liver than in kidney during active and hibernating periods. Protein concentration was decreased significantly in both the tissues during hibernation. LDH activity was significantly higher in the hibernating period in both liver and kidney. SDH activity was significantly reduced in liver during hibernation but increased significantly in kidney. There was a significant decrease in G-6-PDH activity in liver but only a slight decrease in kidney during hibernation.

Transketolase from the leaves of Nicotiana tabacum var. John William′s Broadleaf is inhibited by exposure to low intensity blue light in the presence of low concentrations of FMN, which functions as a sensitizer. The degree of photoinactivation is reduced in the presence of quenchers of triplet FMN. Photoinactivation does not occur in the absence of oxygen and is also lessened in the presence of quenchers of singlet oxygen. The mechanism of photooxidation is inferred to proceed by way of triplet FMN and a major route of inactivation of the enzyme may continue via singlet oxygen.

Electron densities at the nucleus of several simple phenols and plant phenols such as catechin and quercetin are calculated by the HMO-method. We found a correlation between the maximum of the electron density at the nucleus and the extinction value of the reaction product with vanillin. With the exception of quercetin an explanation is given by the HMO-calculation. Investigations into the structure of the reaction products have been carried out.

Investigations on hybrid DNA of B. subtilis after irradiation with long wavelength UV (313 nm) indicate that single strand breaks are produced in the T-strand. These lesions are not observed in normal DNA. Since the action of diffusible photoproducts could be excluded the occurrence of single strand breaks in the T-strand may be due to intramolecular energy transfer. Measuring the breakage rates for the T- and B-strand by employing analytical ultracentrifugation it was found that up to 5% of the energy absorbed in the B-strand can be transferred to the T-strand and causes there single strand breaks. The breakage rates per erg-mm- 2 for single strand breaks after long wavelength UV are determined to be a T = 0.5 · 10 -4 and a B = 10 · 10 -4 breaks/10 6 Dalton for the T- and B-strand of hybrid DNA respectively.

The influence of ionizing radiation on the turnover of high molecular weight RNA in mammalian cells was studied. Growing cultures of suspended human amnion cells were labeled with 32 P and irradiated with different doses of X-rays. RNA was isolated by hot phenol and the high molecular weight RNA fractionated by chromatography on methylated serum albumin celite columns. The salt gradient eluted RNA with sedimentation coefficients of 16 S or greater, which were characterized by analysis of nucleotide composition. Irradiation with doses from 900—6000 R results in degradation of pre-labeled RNA. A quantitative determination reveals that more 32 P-radioactivity leaves the high molecular weight RNA compared to labeled total material that is degraded to acid soluble products. This indicates that RNA is partly broken down to low molecular weight fragments. Nucleotide analysis of the high molecular weight RNA fractions indicate a preferred degradation of ribosomal precursor RNA. The experimental results give evidence that the analysis of RNA synthesis for a certain period after irradiation is complicated by interfering processes like the simultaneous degradation of RNA.