Type RP Research Articles

Incorporation of phosphonic acid diesters into lipid model membranes Part I. Influence of the esters on the phase behaviour of egg yolk lecithin water systems and their orientational behaviour at low water content as seen by 2H- and 31P-NMR

Mixtures of egg yolk lecithin and phosphonic acid diethyl or dibutyl esters of the general type RP(O) (OR′) 2 with R = hexane or dodecane were studied at low water concentration using 31P- and 2H-NMR. (1) The esters cause a phase transition L α—H II at room temperature. This cannot be observed in pure egg yolk lecithin/water mixtures on decreasing the water content. (2) A redistribution of the esters at the phase transition takes place. The esters are excluded from the more ordered glycerol backbone and are forced into the less ordered hydrocarbon chain region of the lipids. Hexyl phosphonic dibutylester shows some peculiarities. A certain redistribution of these esters already takes place in the L α phase. (3) The angle between the phosphoryl group and the molecular symmetry axis increases in the sequence hexyl dibutyl, hexyl diethyl, dodecyl diethyl ester. It increases also with decreasing water concentration. (4) The molecular order parameter increases in the sequence hexyl dibutyl, hexyl diethyl, dodecyl diethyl ester. It increases significantly in dodecyl ester but not in the others with decreasing water concentration. The results obtained are qualitatively explained by the interplay of different forces.

Stability of difluorophosphines and their platinum complexes

Lutz Heuera, Peter G.Jonesa, Dietmar Schomburgb, and Reinhard Schmutzlera Instut für Anorganische und Analytische Chemie der Technischen Universität, Hagenring 30, 3300 Brauschweig. Federal Republic of Germany (a); Gesselschaft für Biotechnologische Forschung mbH, Mascheroder Weg 1, 3300 Braunschweig, Federal Republic of Germany (b).Compounds involving carbon-bonded λ3P-F are normally unstable because of redox disproportionation, e.g. 2n RPF2 → 1/n(RP)n + n RPF4This type of reactions is fairly slow if sterically demanding organic groups (e.g. tert.-butyl) or strongly electronegative groups (e.g. CF3) are used. The reaction of organolithium compounds (RL.i) with PF2CL[1,2] [RLi + PF2Cl → RPF2 + LiCl] therefore provides a n method of preparing difluorophosphines of the type RPF2 (R = organic substituent). With anthracyl lithium we observed the formation of antracyl difluorophosphine, which dimerized on irradiation. The anthracyl difluorophosphine monomer and dimer are stable with respect to redox disproportionation and the dimer is also moderately air stable; it was characterized by an X-ray diffraction study. The partial hydrolysis of the PF2-group gave compounds of type RP(F)(O)(H). In the case of R = 2,6-diphenoxyphenyl the corresponding fluorophosphonic acid was characterized by n.m.r. spectra and by X-ray diffraction study.Organodifluorophosphines reacted with cis-dichloro(η4-1,5-cyclooctadiene)platinum(II) or K2PtCl4 to form cis-dichloro-bis(organodifluorophosphine)platinum(II) or tetrakis(organodifluoro-phosphine)platinum(O), respectively. These complexes were characterized by n.m.r. spectra and by X-ray diffraction studies for R = But, Me5C5[2]. For complexes involving PF2-groups, a correlation between the Pt-P bond length and 2J(PtF) was found.The tetrakis(aryldifluorophosphine)platinum(O) complexes were found to undergo hydrolysis of the PF2-group and oxidation of the platinum with formation of bis(arylphosphonofluoridate)-bis (arylphosphonofluoridous acid)platinum(II). Bis{bis(2,5-dimethylphenylfluorophosphinito)-difluoro-borato)}platinum(II) is the only product of the reaction of the appropriate {RPF(O)}2Pt{RPF(OH)}2 complex with BF3*Et2O and was characterized by a single crystal X-ray diffraction study.

Efficacy of artificial humic acid as a selective nutrient in HV agar used for the isolation of soil actinomycetes

The efficacies of various kinds of humic acid, as the source of carbon and nitrogen in HV agar reported in the previous paper, were compared to the selective isolation of soil actinomycetes. The 4 types of natural humic acid, A, B, P and Rp were prepared from different soils, and 3 kinds of artificial humic acid were made from carbohydrates and urea in our laboratory. Among the natural humic acids, type Rp, which has been reported to be associated with an initial state of humification in natural conditions, showed the greatest efficacy. However, one of the artificial humic acids, which was prepared from glucose and urea, was considered to be superior to the Rp natural humic acid: 1) The HV agar containing this artificial humic acid (HV-glucose HA agar) produced the same large number of actinomycete colonies on the plate as that of the HV agar with type Rp soil humic acid (HV- Rp agar). 2) The HV-glucose HA agar restricted the number of bacterial colonies on the plates to one-half of that on HV- Rp agar plates. 3) The quality of natural himic acids varies, whereas artificial ones are more constant and can be made in any laboratory.

Neuartige basische Liganden für die homogenkatalytische Homologisierung von Methanol zu Ethanol, II [1]. Synthese und komplexchemisches Verhalten potentiell zwei- und dreizähniger P–N- und P–O-haltiger Chelatliganden / Novel Basic Ligands for the Homogeneous Catalytic Homologation of Methanol to Ethanol, II [1]. Synthesis and Complex Chemical Behaviour of Potential Bi- and Tridentate P–N and P–O Containing Chelate Ligands

Tridentate P-N and P-O ligands of the type RP(XC5H4N)2 (1a, b, a′, b′) [X = O, NH: R = CH3 (a, a′), t-Bu (b, b′)] and PhP(CH2C4H7O)2 (1c″) are obtained by reaction of RPCl2 with 2-hydroxy- and 2-aminopyridine and Li2PPh with tetrahydrofurfuryil chloride, respectively. In a similar way the potential bidentate ligand Ph2PCH2C4H7O (2c″) is formed by the action of LiPPh2 on ClCH2C4H7O. Potential tridentate ligands as RP(C4H3O)2 (3a‴-c‴) [R = CH3 (a‴), t-Bu (b‴), Ph (c‴)| with two furyl-phosphorus bonds can be isolated from RPCl2 and furyllithium. The complex chemical behaviour towards Mo(CO)6 or carbonyl derivatives of chromium was elucidated for 2c‴ and 3a‴- c‴, resulting in the formation of (OC)5MoPPh2CH2C4H7O (4c″) and trans-(OC)4Cr[RP(C4H3O)2]2 (5a‴-c‴), respectively. In the case of 5a‴ an X-ray investigation proved 3a‴-c‴ to be only monodentate P-ligands 5a‴ crystallizes in the monoclinic space group P21/c with Z = 2. 1c″ is the most versatile species within this series and functions probably as a tri-, bi- and monodentate P-O ligand. With 1c″ and 3c″ some homologation experiments of methanol at 200 °C and 304 bar synthesis gas pressure were carried out

Phospha-alkene durch thermische, basen- oder metall-induzierte eliminierung

Thermal, base- and metal- induced 1,2-elimination reactions at P-halogen phosphanes of the type RP(Hal)-C(X)R 1R 2 were used for the preparation of phospha-alkenes with a new-type pattern of substitution at the (PC)-double-bond. The different methods are discussed in more detail.

Catalytic activity of rhodium(I) complexes containing (ω-trimethylsilylalkyl)diphenylphosphines

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from μ,μ'-dichloro-bis(cyclooctenerhodium) and phosphines of the type RP(C6H5)2 (R = -CH3, -(CH2)nSi(CH3)3; n = 1-4) have been studied. The substitution of the ligands by the trimethylsilyl group was found to increase significantly the catalytic activity of the complexes. The results are discussed in relation to the electron density on the phosphorus atom determined by 31P NMR spectroscopy and to its proton acceptor ability determined by IR spectroscopy.

Phosphorus–nitrogen rotation barriers: Further studies

AbstractPhosphorus–nitrogen rotation barriers have been determined by low temperature NMR methods in a variety of compounds of the type RP(X)NR2′. The observed activation parameters are concentration and solvent independent. Increasing the bulk of substituents on nitrogen increases the barrier. Phosphonamidous fluorides (X = F) have lower barriers than the corresponding chlorides (X = Cl). Increasing the bulk of substituents on phosphorus decreases the barrier.