Abstract: Disclosed are compositions from which radically initiated oligomers/polymers having a controlled molecular weight, low polydispersity and a vinyl or dienyl end group are prepared. Further subjects of the invention are a process for controlled radical polymerization, oligomers/polymers obtainable by said process and the use of specific addition fragmentation agents for the polymerization process. The addition fragmentation agents are new in part and these are also subject of the present invention. The addition fragmentation agents are of the formula (Ia), (Ib) or (Ic) where Y is a group which activates the double bond towards Michael addition.

Abstract: Synthesis of linear acrylic polymers and copolymers having controlled molecular weight by the photoinitiated free radical polymerization of vinyl monomers in the presence of chain transfer agents to produce polymers useful in coating compositions and the like, including printing inks.

Abstract: A Process for the selective preparation acrylate- or methacrylate-homo- or acrylate- or methacrylate-co-oligomers with a weight average molecular weight (Mw) from 1000 to 20000, a polydispersity≦3 and a conversion of the monomers to polymers greater than or equal to 70%, or for the selective preparation of polyvinylacetate and its hydrolysis product polyvinylalcohol with a weight average molecular weight (Mw) from 1000 to 25000, a polydispersity≦3 and a conversion of the monomers to polymers greater than or equal to 70%, is characterized in that a mixture of the corresponding monomers is irradiated in the presence of a specific photoinitiator or photoinitiator mixture at a temperature from −20 to 70° C. in an inert solvent or inert solvent mixture, with light of a wavelength from 305 to 450 nm, wherein the contents of monomers in the reaction mixture is up to 70%.

Abstract: Compounds of the formula I, II, III and IIIa ##STR1## in which Ar.sup.1 is an unsubstituted or substituted aromatic radical and at least one of the radicals R.sup.1 and R.sup.2 is an alkenyl, cycloalkenyl or arylmethyl group, are effective photoinitiators for photopolymerization of unsaturated compounds. They are particularly suitable for photocuring of pigmented systems.

Abstract: Compounds of the formula I, II, III and IIIa ##STR1## in which Ar.sup.1 is an unsubstituted or substituted aromatic radical and at least one of the radicals R.sup.1 and R.sup.2 is an alkenyl, cycloalkenyl or arylmethyl group, are effective photoinitiators for photopolymerization of unsaturated compounds. They are particularly suitable for photocuring of pigmented systems.

Abstract: Compounds of the formula I, II, III and IIIa ##STR1## in which Ar.sup.1 is an unsubstituted or substituted aromatic radical and at least one of the radicals R.sup.1 and R.sup.2 is an alkenyl, cycloalkenyl or arylmethyl group, are effective photoinitiators for photopolymerization of unsaturated compounds. They are particularly suitable for photocuring of pigmented systems.

Abstract: Fluorine-free titanocene compounds of the formula I or II ##STR1## in which both R.sub.1 radicals are preferably, independently of one another, cyclopentadienyl.sup..crclbar., which is unsubstituted or substituted by alkyl,alkoxy or --Si(R.sub.2).sub.3, and both R.sub.2 radicals are, in particular, alkyl, ##STR2## Z is --NR.sub.10 --, --0-- or --S--, Y is Cl, Br, I, CN, SCN, --O--CO--CH.sub.3, --O--CO--phenyl or --O--SO.sub.2 --CH.sub.3,n is 1 or 2,m is 0 or 1, where the sum of n and m must be 2,R.sub.3, R.sub.4 and R.sub.5 are in particular, independently of one another, hydrogen, Cl, alkyl, cycloalkyl, adamantyl, phenyl, pyrryl or biphenylyl, where these radicals are unsubstituted or substituted by alkyl, Cl, alkylthio, --NR.sub.8 R.sub.9, phenyl, phenylthio or C.sub.1 -C.sub.10 alkoxy, or R.sub.3, R.sub.4 and R.sub.5 are alkenyl, alkoxy, cycloalkoxy, phenoxy, benzyloxy, tetrahydrofurfuryloxy, alkylthio, cycloalkylthio, benzylthio or phenylthio, where R.sub.3 and R.sub.

Abstract: Titanocenes of the formula I ##STR1## in which R.sup.1 are cyclopentadienyl.sup..crclbar. groups and R.sup.2 and R.sup.3 are aromatic radicals which are substituted in both ortho-positions by fluorine and, in addition, are substituted by an acyloxy group are suitable as photoinitiators for the photopolymerization of ethylenically unsaturated compounds.

Abstract: There is disclosed a process for the preparation of compounds of formula I[R Fe R.sup.2 ].sub.q.sup..sym. X.sup.q.crclbar. (I),wherein R is an anion of formula C.sub.5 H.sub.4 R.sup.1 or C.sub.9 H.sub.7, R.sup.1 is hydrogen, C.sub.1 -C.sub.6 -alkyl or halogen R.sup.2 is a .pi.-arene, X is an anion of valency q and q is 1, 2 or 3, by reacting ferrocene or a ferrocene derivative (C.sub.5 H.sub.4 R.sup.3)Fe(C.sub.5 H.sub.4 R.sup.1) or (C.sub.9 H.sub.7).sub.2 Fe, in which R.sup.3 has one of the meanings of R.sup.1, with at least one mole of a .pi.-arene R.sup.2, followed by the optional replacement of the anion X.sup.q.crclbar. in a manner known per se, the reaction of the ferrocene or ferrocene derivative being carried out in the presence ofa) at least 1.2 mol of a mixture of Al trihalide and Zr(IV) or Hf(IV) tetrahalide, in the presence or absence of a metallic reducing agent, such that at least 0.2 mol of Zr(IV) or Hf(IV) tetrahalide and at least 0.1 mol of Al trihalide are present, or ofb) at least 1.

Abstract: Titanocenes of the formula I ##STR1## in which R.sup.1 are cyclopentadienyl.sup..crclbar. groups and R.sup.2 and R.sup.3 are aromatic radicals which are substituted in both ortho-positions by fluorine and, in addition, are substituted by an acyloxy group are suitable as photoinitiators for the photopolymerization of ethylenically unsaturated compounds.

Abstract: Compounds of the formula I, II, III and IIIa ##STR1## in which Ar.sup.1 is an unsubstituted or substituted aromatic radical and at least one of the radicals R.sup.1 and R.sup.2 is an alkenyl, cycloalkenyl or arylmethyl group, are effective photoinitiators for photopolymerization of unsaturated compounds. They are particularly suitable for photocuring of pigmented systems.

Abstract: An improved preparation of titanocenes of the formula I ##STR1## in which R.sub.1 is cyclopentadienyl.sup..crclbar., indenyl.sup..crclbar. or 4,5,6,7-tetrahydroindenyl.sup..crclbar., each of which is unsubstituted or monosubstituted or polysubstituted by C.sub.1 -C.sub.18 alkyl, C.sub.1 -C.sub.18 alkoxy, C.sub.2 -C.sub.18 alkenyl, C.sub.5 -C.sub.8 cycloalkyl, C.sub.6 -C.sub.10 aryl, C.sub.7 -C.sub.16 aralkyl, --Si(R.sub.3).sub.4, --Ge(R.sub.3).sub.4 or halogen, or the two R.sub.1 radicals together are a divalent radical of the formula II ##STR2## in which Z is --(CH.sub.2).sub.m -- where m=1, 2 or 3, unsubstituted or phenyl-substituted C.sub.2 -C.sub.12 alkylidene, --Si(R.sub.3).sub.2 -- or --Si(R.sub.3).sub.2 --O--Si(R.sub.3).sub.2 --, and R.sub.3 is C.sub.1 -C.sub.12 alkyl or C.sub.6 -C.sub.10 aryl, and R.sub.

Abstract: There is disclosed a process for the preparation of compounds of formula I[R Fe R.sup.2 ].sub.q.sup..sym. X.sup.q.crclbar. (I),wherein R is an anion of formula C.sub.5 H.sub.4 R.sup.1 or C.sub.9 H.sub.7, R.sup.1 is hydrogen, C.sub.1 -C.sub.6 -alkyl or halogen, R.sup.2 is a .pi.-arene, X is an anion of valency q and q is 1, 2 or 3, by reacting ferrocene or a ferrocene derivative (C.sub.5 H.sub.4 R.sup.3)Fe(C.sub.5 H.sub.4 R.sup.1) or (C.sub.9 H.sub.7).sub.2 Fe, in which R.sup.3 has one of the meanings of R.sup.1, with at least one mole of a .pi.-arene R.sup.2, followed by the optional replacement of the anion X.sup.q.crclbar. in a manner known per se, the reaction of the ferrocene or ferrocene derivative being carried out in the presence of(a) at least 1.2 mol of a mixture of Al trihalide and Zr(IV) or Hf(IV) tetrahalide, in the presence or absence of a metallic reducing agent, such that at least 0.2 mol of Zr(IV) or Hf(IV) tetrahalide and at least 0.1 mol of Al trihalide are present, or of(b) at least 1.

Abstract: A process is described for preparing compounds of the formula I[R Fe R.sup.2 ].sub.q .sym.X.sup.q.crclbar. (I)in which R is an anion of the formula C.sub.5 H.sub.4 R.sup.1 or C.sub.9 H.sub.7, R.sup.1 is hydrogen, C.sub.1 -C.sub.6 -alkyl or halogen, R.sup.2 is a .pi.-arene, X is a q-valent anion and q is 1, 2, 3 or 4, by reacting ferrocene or a ferrocene derivative (C.sub.5 H.sub.4 R.sup.3)Fe(C.sub.5 H.sub.4 R.sup.1) or (C.sub.9 H.sub.7).sub.2 Fe, in which R.sup.3 has one of the meanings of R.sup.1, with at least one mole of a .pi.-arene R.sup.2 in the presence of at least 1.4 moles, of a mixture of Al halide and Ti(IV) halide or (C.sub.5 H.sub.4 R.sup.1)-Ti(IV) halide if desired in the presence of a metallic reducing agent, followed if desired by the replacement of the anion X.sup.q- in a manner known per se, with the proviso that the Lewis acid mixture contains at least 0.1 mole of Al halide and at least 0.