SYNOPSISThe curing of epoxy resins using dicyandiamide (DICY) and combinations of DICY with several uron accelerators as curing agents is investigated. DSC, FTIR, mechanical, and sorption measurements indicate complex multistage curing processes. There is no evidence that the curing reaction is catalyzed by DICY. The optimum stoichiometry is determined as 7 epoxy units per 1 molecule DICY. Contour plots for curing reactions with DICY in presence of Fenuron 3c or TDI-uron 3d give some information for optimizing technical formulations.

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6721 Scheme I11 CI I I CHzCI2 + C u C I / P ( O E t ) 3 hr CICH2-Cu-CI P(OEtI3 CICH,;(OEt ) 3 C I --t CUCl I CICH2PO(OEt)z 4-E t C l 2 acrylate may also be explained reasonably by a similar two electron oxidative addition-reductive elimination pathway (Scheme 111). 2 was not obtained without assistance of photoirradiation or in a photochemical reaction without CuCl catalyst. The reactions of Scheme I1 and I11 further suggest that pathway a and not b of Scheme I is involved in copper(1)-catalyzed photoaddition of alkyl halides to olefins. Acknowledgment. This work was supported by a Grant-in-Aid for Scientific Research (No. 56550606) from the Ministry of Education, for which we are grateful. Registry No. CH,(CH,),Br, 109-65-9; c-C6Hl,Br, 108-85-0; (C-H,),CBr, 507-19-7; Br(CH,),Br, 110-52-1; Br(CH,),Br, 109-64-8; Br-(CH,),Br, 106-93-4; Br(CH,),COOEt, 539-74-2; CH3(CH2),C1, 109-CHCOMe, 78-94-4; CH2=C(Me)CN, 126-98-7; CH,=C(Me)COOEt, 97-63-2; CH2=C(COOEt)CH2COOEt, 2409-52-1 ; cis-CH(COOEt)= CH(COOEt), 141-05-9; CuC1, 7758-89-6; CuBr, 7787-70-4; (n-Bu),P, 998-40-3; CH3(CH,),

The copper atoms are displaced slightly from their ideal positions at the midpoints of the edges of the Sx cube towards the (unoccupied) center; the S-Cu-S fragments are therefore not linear but exhibit angles between 166.87(7) and 170.89(7)' at the Cu atom with bond lengths between 2.156(2) and 2.179(2) A (average 2.163 A).

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