Modified thioxanthone photoinitiators

A compound of Formula II:

• wherein:
• m=0, 1, 2, 3 or 4;
• and
• one of the aromatic rings is di-substituted, at the 3 and 4 positions of the thioxanthone ring, with substituents independently selected from —O—C(1-6)alkylhydroxy group or a carboxylate ester thereof, a —O—C(1-6)alkylthio group, a —O—C(1-6)alkylamino group, and a —O—C(1-6)carboxylate ester group wherein the ester portion comprises a C1-6 alkyl group and/or a 4- to 10-membered carbocyclic group, wherein the 3 and 4 position substitution optionally produces a 5-membered benzodioxole ring;
• or
• one or both of the aromatic rings is substituted with at least one substituent independently selected from hydroxy, alkoxy, benzyloxy, alkylcarbonate, hydroxyalkyl, acetal, ester, oxyacetic acid and esters thereof, aryloxy and arylthio;
• and
• L=a linker group.

A compound selected from:

• 2-[4′-(2-acetoxyethoxy)spiro[1,5-dihydro-2,4-benzodioxepine-3,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[4′-(2-hydroxyethoxy)spiro[1,5-dihydro-2,4-benzodioxepine-3,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-[4′-(2-acetoxyethoxy)-5-phenyl-spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[4′-(2-hydroxyethoxy)-5-phenyl-spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-[4′-(2-acetoxyethoxy)-5,5-dimethyl-spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[4′-(2-hydroxyethoxy)-5,5-dimethyl-spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-[4′-(2-acetoxyethoxy)spiro[1,3-dioxepane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[4′-(2-hydroxyethoxy)spiro[1,3-dioxepane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-[4′-(2-acetoxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[4′-(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-[4′-(2-acetoxyethoxy)-5-[4-[3′,4′-bis(2-acetoxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-5-yl]phenyl]spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[5-[4-[3′,4′-bis(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-5-yl]phenyl]-4′-(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• 2-{3′-[2-(acetyloxy) ethoxy]-5-{4′-[2-(acetyloxy) ethoxy]-3′-{2-[(1-hydroxyethenyl)oxy]ethoxy}spiro[1,3-dioxane-2,9′-thioxanthen]5-yl}spiro[1,3-dioxane-2,9′-thioxanthen]-4′yloxy}ethyl acetate;
• 2-{5′-[3′,4′-bis(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′thioxanthen]-5-yl]-3′-(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′thioxanthen]-4′-yloxy}ethan-1-ol;
• 2-{3,4′″-bis[2-(acetyloxy) ethoxy]-3″′-{2-[(1-hydroxyethenyl)oxy]ethoxy}trispiro[thioxanthene-9,2′:
• 5′m5″-bis([1,3]dioxane)-2″,9′″-thioxanthen]4-yloxy}ethyl acetate;
• 2-[3,3′″,4′″-tris(2-hydroxyethoxy) trispiro[thioxanthene-9,2′:
• 5′,5″-bis([1,3]dioxane)-2″,9′″-thioxanthen]-4-yloxy]ethan-1-ol;
• 2-{3′-[2-acetyloxy) ethoxy]-5-{4′-[2-(acetyloxy) ethoxy]-3′-{2-[(1-hydroxyethenyl)oxy]ethoxy}spiro[1,3-dioxane-2,9′thioxanthen]-5-yl}spiro[1,3-dioxane-2,9′-thioxanthen]-4′yloxy}ethyl acetate;
• 2-{5-[3′,4′-bis(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthen]-5-yl]-3′-(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthen]4′-yloxy}ethan-1-ol;
• 2-{3″,4″,6-tris[2-acetyloxy) ethoxy]-1′,5′,5′a,6′,10′,10′a-hexahydrospiro[thioxanthene-9,8′-[2,4,7,9]tetraoxaheptalene-3′,9″thioxanthen]-5-yloxy}ethyl acetate;
• 2-[3″,4″,6-tris(2-hydroxyethoxy)-1′,5′,5′a,6′,10′,10′a-hexahydrodispiro[thioxanthene-9,8′-[2,4,7,9]tetraoxaheptalene-3′,9″-thioxanthen]5-yloxy]ethan-1-ol;
• 2-[4′-(2-acetoxyethoxy)-5-[2-[3′,4′-bis(2-acetoxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-5-yl]ethyl]spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethyl acetate;
• 2-[5-[2-[3′,4′-bis(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-5-yl]ethyl]-4′-(2-hydroxyethoxy)spiro[1,3-dioxane-2,9′-thioxanthene]-3′-yl]oxyethanol;
• or 5-[2-(3′,4′-dimethoxyspiro[1,3-dioxane-2,9′-thioxanthene]-5-yl) ethyl]-3′,4′-dimethoxy-spiro[1,3-dioxane-2,9′-thioxanthene].