摘要:
A process is described for preparing polyoxymethylene by contacting a formaldehyde source with a catalyst of the formula I [ML1aL2b]cm+Zc·m/nn− (I) where M is a metal of group VIII; L1 is a ligand having at least one π-electron pair; each L2 is independently tetrahydrofuran or a ligand which is displaceable by tetrahydrofuran; Z is an anion; a is 1 or 2; b is an integer from 0 to 4; c is 1 or 2; and m and n are integers from 1 to 4.
摘要:
A process is described for preparing polyoxymethylene by contacting a formaldehyde source with a catalyst of the formula I [ML1aL2b]cm+Zc·m/nn− (I) where M is a metal of group VIII; L1 is a ligand having at least one π-electron pair; each L2 is independently tetrahydrofuran or a ligand which is displaceable by tetrahydrofuran; Z is an anion; a is 1 or 2; b is an integer from 0 to 4; c is 1 or 2; and m and n are integers from 1 to 4.
摘要:
A process is described for preparing polyoxymethylene by contacting a formaldehyde source with a catalyst of the formula I [CpvMLw]m+Zm/nn− (I) where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh or Ir, Cp is a cyclopentadienyl ligand C5H(5-u)R1u, where u is from 0 to 5 and R1 is alkyl, alkenyl, aryl, heteroaryl, aralkyl, COOR2, COR2, CN or NO2, and R2 is H, alkyl, aryl or aralkyl, v is 1 or 2, each L is independently a nitrile, CO or a ligand displaceable by CO, w is an integer from 0 to 4, Z is an anion, and m and n are each independently an integer from 1 to 3.
摘要:
A process is described for preparing polyoxymethylene by contacting a formaldehyde source with a catalyst of the formula I [CpvMLw]m+Zm/nn− (I) where M is Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Os, Co, Rh or Ir, Cp is a cyclopentadienyl ligand C5H(5−u)R1u, where u is from 0 to 5 and R1 is alkyl, alkenyl, aryl, heteroaryl, aralkyl, COOR2, COR2, CN or NO2, and R2 is H, alkyl, aryl or aralkyl, v is 1 or 2, each L is independently a nitrile, CO or a ligand displaceable by CO, w is an integer from 0 to 4, Z is an anion, and m and n are each independently an integer from 1 to 3.
摘要:
Process for preparing an aqueous polymer dispersion by polymerization of at least one olefinically unsaturated compound in an aqueous medium in the presence of at least one dispersant and a solid polymerization catalyst.
摘要:
Water-soluble transition metal complexes of the formula (I) where R1 to R4 are linear or branched C2- to C28-alkyl, C3- to C14-cycloalkyl or alkylaryl where the alkyl moiety is of 1 to 28 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, each of which is substituted by at least one polar protic or ionic functional group based on nonmetallic elements of groups IVA to VIA of the Periodic Table of Elements.
摘要:
A diesel fuel containing an additive which improves the combustion of soot, for reducing the pollutant emission in the combustion exhaust gases from diesel engines by discontinuous burning-off of soot which has been precipitated in the exhaust gas filter, is described. For this purpose, a lithium, sodium or potassium salt of an aliphatic or aromatic alcohol, of a phenol, of an aliphatic acid or of a naphthoic acid, phenylacetic acid or cinnamic acid is added, singly or as a mixture, to the diesel fuel before the combustion of the latter in the internal combustion engine. As a result of the addition of the alkali metal salts, the ignition temperature of the soot precipitated in the particle filter is reduced, and the soot is oxidized at a temperature which is considerably lower than the normal ignition temperature. The regeneration range for the particle filter is therefore reached much more frequently in real running practice. This avoids a critical filter loading with soot, which can lead to filter damage during burning off. A further advantage of the process described is that, according to present knowledge, no additional substances with a health risk are emitted during running as a result of the addition of these alkali metal salts to the diesel fuel.
摘要:
Process for preparing an aqueous polymer dispersion by polymerization of at least one olefinically unsaturated compound in an aqueous medium in the presence of at least one dispersant and a solid polymerization catalyst.
摘要:
Catalyst systems for the copolymerization of carbon monoxide and α-olefinically unsaturated compounds contain, as essential components, a) a metal complex of the formula (I) where R1 to R4 are each linear or branched C2- to C28-alkyl, C3- to C14-cycloalkyl or alkylaryl where the alkyl moiety is of 1 to 28 carbon atoms and the aryl moiety is of 6 to 15 carbon atoms, each of which is substituted by at least one polar protic or ionic functional group based on elements of groups IVA to VIA of the Periodic Table of Elements, and b) if required, one or more Lewis or protic acids or a mixture of Lewis and protic acids.