Synthesis of spirosilicates directly from silica and ethylene glycol/ethylene glycol derivatives Varangkana Jitchum, a Sun Chivin, a Sujitra Wongkasemjit a,p and Hatsuo Ishida b a The Petroleum and Petrochemical College, Chulalongkorn University, Bangkok 10330, Thailand b The Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106, USA Received 11 December 2000; revised 5 February 2001; accepted 22 February 2001 Abstract ÐTetracoordinated spirosilicates have been synthesized directly from the reaction of a very inexpensive and plentiful material, SiO 2 , and ethylene glycol in the presence of triethylenetetramine TETA), as catalyst with and without potassium hydroxide as co-catalyst. The reactions are run under nitrogen gas with constant stirring at 2008C, and complete in a reaction time of 10±18 h depending on the catalysts. The reactions using only TETA are complete in 18 h, while with potassium hydroxide the reactions occur much more quickly. When 3-amino-1,2-propanediol, or 2-amino-2-methyl-1,3-propanediol is employed, the reaction must run under vacuum at 0.1mmHg, 1608C, and is complete in 14 and 24 h, respectively. The structures of spirosilicates are fully characterized using FTIR, 1 H, 13 C, 29 Si NMR, FAB 1 -MS, and TGA. q 2001 Elsevier Science Ltd. All rights reserved. 1. Introduction Generally, thermosetting resins undergo a volumetric shrinkage 3±15%) during polymerization even using the best system. 1±3 However, resins without shrinkage would be advantageous for such applications as precision castings, dental composites, rock cracking materials, and high strength composites. The superior mechanical interlocking to a substrate that would be possible with zero shrinkage or expanding materials makes them ideally suited for higher performance adhesives, sealants and coatings. 4±7 Most of the spiroorthocarbonate and spiroorthoester monomers show little or no volume shrinkage or expansion in volume upon polymerization. However, they do provide a few useful applications with low glass transition temperature. Moreover, spiroorthocarbonates and spiroorthoesters can only be synthesized from complicated routes. 8±13 Frye reported the preparation of spirosiloxane from SiOEt) 4 and ethylene glycol in ethanol with a small amount of NaOMe. The product obtained was polymeric species and in the presence of amine bases, novel pentacoordinated species would be formed Scheme 1). 14±16 Laine et al. synthesized pentacoordinated and hexacoordi- nated spiro-silicates directly from silica and ethylene glycol Tetrahedron 57 2001) 3997±4003 Pergamon TETRAHEDRON 0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII: S0040-402001)00275-7 Keywords: silica; tetracoordinated spirosilicates; aminospirosilicates. p Corresponding author. Tel.: 166-2-218-4133; fax: 166-2-215-4459; e-mail: dsujitra@chula.ac.th Scheme 1. Scheme 2.