Iranian Journal of Chemistry and Chemical Engineering
Volume:15 Issue: 2, Nov-Dec 1996

The complex[PtMe4(dppm)],dppm=bis(diphenylphosphino)methane, reacts with thiols, RSH, to give fac-[PtMe3(SR)(dppm)], whereR= m-CH3(C6H4), Ph, and PhCH2. The complex also reacts withCF3COOH and HgCl2 to give fac-[PtMe3(OCOCF3)(dppm)] and fac-[PtMe3Cl(dppm)], respectively. Reaction of [PtMe4(PMe2Ph)2] with SO2gives the S-sulfinate derivative fac-[PtMe3(SO2Me)(PMe2Ph)2]. In eachcase, one of the mutually trans methyl groups in the tetramethylcomplexes, is attacked by the electrophilic reagents.

Metalloporphirins; Cu(TPP),Mn(TPP)Cl,Co(TPP), Fe(TPP)Cl,Zn(TPP), and Mn(OBP)Cl catalyze regio and chemoselective silylation ofhydroxy groups with HMDS. Fe(TPP)Cl is the most effective catalyst andsilylation occurs immediately in its presence at room temperature.

An efficient synthesis of the 1,4- dihydroxy-9(10H)- anthra-cenone (2) is described. Bromination of phthalide, treated with 1,4-di-methoxybenzene, oxidation with ceric ammonium nitrate(CAN) in aqueousacetonitrile, reduction with zinc dust in glacial acetic acid affordedhydroquinone 14 in good yield. Further reduction with zinc dust inaqueous sodium hydroxide, and cyclization with trifluoroacetic acid andtrifluoroacetic anhydride produced the title compound in high yield.

The difficult to handle and store zinc borohydride,Zn(BH4)2, is stabilized by supporting it on polyvinylpyridine. This newmild, efficient, selective, and regenerable polymer supported borohydridereducing agent reduces a variety of organic compounds such as, aldehydes,a, b-unsaturated carbonyl compounds, acid chlorides, epoxides, disulfides,as well as reductive acetylation of carbonyl compounds. It absolutely dis-criminates aldehydes from ketones.

The epoxidation of styrene by sodium periodate is catalyzedby (acetato-tetraphenylporphyrinato) manganese(III)/tetra-n- butylammo-nium bromide in the presence of various polybenzimidazole modelcompounds in CH2Cl2-H2O media with high yields (75-84%) and absoluteselectivities in 3 hours at ambient temperature.

Synthesis of 4-(N,N- dimethylamino)-3-aryl-3-butene-2- one,ethyl-5-aryl-4-oxo-4H-pyran-2-carboxylate, ethyl-5-aryl-4-pyridones-2- carboxy-late and 5-aryl-3-cyano-5-methyl-2-pyridones (aryl=3-thienyl, 2-furyl) aredescribed.

Catalytic amount of 2,3-dichloro-5,6-dicyano benzoquinone(DDQ) can bring about an efficient transetherification of allylic andtertiary benzylic ethers in primary, secondary and tertiary alcohols.Etherification of allylic acetates and esterification of allylic ethers can bealso performed catalytically in the presence of DDQ.

Fourier transform infrared (FTIR) and gel permeation chro-matography (GPC) were respectively utilized in determining the changes inisocyanate (NCO) concentration and molecular weight (MW) and its dis-tribution (MWD) in polyurethanes during their cure and postcure stages. Samples, originally cured at 45ـC, were taken through accelerated agingtests at various temperatures. The FTIR and GPC analytical conditionswere optimized, for both molecular weight and molecular weight distri-bution and NCO group determination. In FTIR spectroscopy Beers lawwas obeyed over the ranges: 2. 33-22. 34 and 0. 03-1. 61 mmol lit-1. RSD, detection limit and molar absortivity were found to be 1. 46%, 4خ10-6 mollit-1 and 1095 lit mol-1 cm-1 respectively. It was found the NCO concen-tration decreases with the progress of polymerization and at the same timeMW of the sol increases, going through a maximum and then decreases toa constant level. The time to reach this level and termination of NCO con-centration, i. e., the end of polymerization decreases with the increase intemperature. The results obtained from GPC and FTIR methods in follow-ing the different steps of polymerization as well as those from the linearplots of the end time of reaction vs. the 1/T, were in good agreement.

Anionic polymerization was used for synthesis of block copo-lymers of styrene-t-butylmethacrylate and styrene dimethylaminoethyl-methacrylate, using cumyl potassium and naphthalene potassium as initia-tors for diblock and triblock copolymers, respectively. The 1, 1إ- diphenyl-ethylene (DPE) was added to reduce the activity of the growing chain

The interactions of Tl(I) ions with adenosine-5-monophos-phate(5-AMP), and guanosine-5-monophosphate (5-GMP) anions inratios 1 and 2 have been studied in acidic and neutral pH s. The solidcomplexes were isolated and characterized by FTIR and 1H NMR spec-troscopy. In the Tl2-AMP, Tl+ bind indirectly to N-7 and directly tophosphate group with sugar moiety in C2-endo/anti conformation. In theacidic solution, there is no direct binding between Tl+ and GMP-2. Acidi-fication of Na2-GMP causes conformational change of sugar moiety fromC2-endo/anti to C3-endo/anti. The crystalline salt of Tl2-GMP isolatedfrom neutral solution show direct Tl-N-7 (inner sphere) and indirect Tl-PO3binding through metal hydration shell (outer sphere). The conformation ofribose moiety in Tl2-GMP (neutral) is C3-endo/anti.

The 3,5-di(trifluoromethyl)benzyl hydroxylamine hydro-chloride (DTFMBO), a new derivatizing agent was synthesized for theanalysis of carbonyl compounds using gas chromatography-mass spectro-metry. The DTFMBO-TMS derivatives of testosterone and hydrocortisoneand DTFMBO derivatives of 4-androstene-3,17-dione and, progesteronewere prepared. These were injected into gas-chromatograph-mass spectro-meter (GC-MS) under negative ion chemical ionization (NICI). The massspectra under NICI conditions showed less fragmentation and highabundance of significant ions. These derivatives will be suitable for theanalysis of sample containing low concentration of steroids using GC-MSunder negative ion chemical ionization (NICI) with selected ionmonitoring (SIM).