Trimethylsilyl- and trimethylstannyldimethylphosphane--convenient and versatile reagents for the synthesis of polyfluoroaryldimethylphosphanes.
Trimethylsilyldimethylphosphane (Me3SiPMe2) and the corresponding tin compound (Me3SnPMe2) were used as reagents for the substitution of fluorine by the Me2P group in polyfluoroarenes C6F5X (X = F, H, Cl, CF3) and C5NF5. The reactions occur even under mild conditions (T = 0-20 C), either in benzene or without solvent, to give as a rule 4-X-1-(dimethylphosphano)tetrafluorobenzenes (XC6F4PMe2, 1-4) and 4-(dimethylphosphano)tetrafluoropyridine (C5NF4PMe2, 5), respectively, in yields between 75 and 95%. In the case of C6F6, double substitution is also observed, which affords 1,4-bis(dimethylphosphano)tetrafluorobenzene (6). A very efficient route to the compounds XC6F4PMe2 (X = F, H, Cl, CF3) and C5NF4PMe2 was developed as a one-pot reaction of the corresponding fluoroarenes with tetramethyldiphosphane (P2Me4) and trimethyltin hydride (Me3SnH) at moderate temperatures. This process was tested for C6F6 and perfluorobiphenyl which gave C6F5PMe2 (1) and 4,4'-bis(dimethylphosphano)octafluorobiphenyl (7), respectively. The results, which included kinetic measurements that used the intensities of the 31P signals, revealed the influence of the substrate type on the rate of reaction in the sequence: C5NF5>C6F5CF3> C6F5Cl, C6F5PMe2>C6F5H>C6F6>> C6H5F. Ab initio calculations were carried out on the model reactions of pentafluoropyridine with silylphosphane, phosphane or phosphide to discriminate between possible reaction mechanisms. The novel phosphanes were characterised by spectroscopic investigations (NMR, MS), by preparation of the related thiophosphanes ArFP(=S)Me2 (8-14), their spectroscopic and analytic data and single crystal X-ray diffraction studies on five of these derivatives.
Compounds R1R2EMMe3 (E = P, As; M = Si, Sn) - Convenient and Versatile Reagents for the Syntheses of Tertiary (Fluoroaryl)phosphanes and -arsanes
Synthetic and mechanistic aspects of nucleophilic replacement of fluorine in fluorobenzenes, fluoropyridines and fluoroquinolines by phosphanyl and arsanyl groups via their reactions with R 1 R 2 EMMe 3 (E = P, As; M = Si, Sn; R 1 , R 2 = Me, i-Pr, t-Bu, Ph, etc.) reagents are considered.
A sustainable development indicator for NGOs and international organisations
The article offers an easy-to-use indicator for measuring whether NGOs, international organisations and government policies and projects meet the criteria for sustainable development that have been established by the Rio Declaration in 1992 and that are recognised by experts in the field. Use of this indicator reveals that most of the major actors in the field of development are actually failing to promote sustainable development and points to the specific areas where they need to improve in order to fulfil sustainability criteria. We also offer a sample test of the indicator using UNICEF as a case study.