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New insights into the AKD sizing mechanism Kyle J. Bottorff and Mark J. Sullivan, Hercules Incorporated, Wilmington, Delaware, USA Keywords: Alkylketene dimers, AKD, Reaction mechanisms, Solid State "C NMR, Sizing, P-Keto acid, P-Keto calcium salt, P-Keto ester, AKD oligomers. SUMMARY: Paper samples sized with 13C labeled alkylketene dimer (AKD) dispersions were characterized by solid state carbon NMR resulting in direct evidence supporting the forma- tion of AKD-cellulose P-keto esters on AKD sized paper. A series of AKD reaction products that may

Pure &Appl. Chem., Vol. 69, No. 3, pp. 601-604, 1997. Printed in Great Britain. Q 1997 IUPAC Generation of radical species by one electron oxidation with metallic compounds for the construction of carbon skeletons Koichi Narasaka Department of Chemistry, School of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan Abstract: By oxidation of P-keto acids, cyclopropanols, and acyl chromate complexes with tris(2-pyridinecarboxylato)manganese(III) (Mn(pic)g), a-keto, p-keto, and alkyl radicals are generated respectively, which react with

-oxygen bond. Alkylketene dimers can also react with water, forming an unstable P-keto acid, which decarboxyl- ates to the corresponding ketone. SOME AKD - REACTIONS R,-CH,-cI-CH-R, II 0 P=o R,-CH=CX-CH -R, &Cell-OH ? Cell I I* 0- C=O $H20 R,-CH,-cX-CH,-R, + ~ ' b ~ ( ~ ) II 1L x = C labell ing position Fig. 1. Some possible AKD-reactions. 26 Nordic Pulp and Paper Research Journal no. 111 986 The hydrolysis was critical in earlier AKD-disper- sion formulas, whereas the rate of hydrolysis is apparently very slow in new AKD-formulas (4). The ring opening