Catalysis Letters 66 (2000) 181–184 181 Double organic modification by 3-chloropropyl and methyl groups on pure silica MCM-41 and Ti-MCM-41: efficient catalyst for epoxidation of cyclododecene Asim Bhaumik a,* and Takashi Tatsumi b a Toyota Central R&D Lab. Inc., Nagakute, Aichi 480-1192, Japan E-mail: e1165@joa.tytlabs.co.jp b Division of Materials Science and Chemical Engineering, Yokohama National University, Yokohama 240-8501, Japan Received 25 January 2000; accepted 11 April 2000 Simultaneous surface modification by 3-chloropropyl and methyl groups on the same Si atoms resulted in hydrophobic and highly ordered mesoporous silica with a very high surface area. 13 C and 29 Si MAS NMR spectra indicate homogeneous grafting of chloropropyl and methyl groups in the silica matrix and this organically modified Ti-MCM-41 shows outstanding catalytic performance in the epoxidation of cyclododecene using tert-butyl hydroperoxide as oxidant. Keywords: Ti-MCM-41, hydrophobicity, 3-chloropropyl, methyl, epoxidation 1. Introduction Since the discovery of ordered mesoporous silica [1,2] and its titanium silicate analog Ti-MCM-41/Ti-HMS [3], there have been continuous efforts to improve their stabil- ity and catalytic performance. Titanium-containing meso- porous silica has been of great interest from academic and industrial viewpoints because of its potential to oxidize very bulky organic substrates which cannot be oxidized efficiently over microporous TS-1 [4] under liquid-phase reaction conditions. Surface modification by incorporating various organic functionalities [5–7] and silylation [8] have been proved to induce hydrophobicity together with sta- bility in these mesoporous materials and thus the catalytic activity of Ti-MCM-41 improved considerably in the liquid- phase oxidation reactions in the presence of water. Ti con- tent of these mesoporous titanium-containing silicas [9] can be increased by a sol–gel method. Very recently we have shown that 3-chloropropyl modification of Ti-MCM-41 [10] can result in highly ordered and hydrophobic mesoporous materials, which show drastic enhancement of catalytic ac- tivity for the epoxidation of alkenes. The present commu- nication reports for the first time the incorporation of two organic groups, 3-chloropropyl and methyl substituents, on the same Si atoms of the mesoporous silica network. These Cl-propyl-methyl-Ti-MCM-41 materials have very high surface area (>1400 m 2 g -1 ), being hydrophobic and efficient catalysts for the oxidation of a bulky organic sub- strate, cyclododecene. * To whom correspondence should be addressed. 2. Experimental Organically modified MCM-41 materials were synthe- sized using a mixture of 3-chloropropyldimethoxymethyl- silane (Shin-etsu Chemicals) and tetraethyl orthosilicate (TEOS, TCI) as Si sources. Cetyltrimethylammonium bro- mide (CTMABr, TCI) was used as a template and tet- ramethylammonium hydroxide (25% aqueous TMAOH, Aldrich) was used to provide alkalinity of the medium. Tetrabutyl orthotitanate (TBOT, Aldrich) was used as Ti source. Isopropyl alcohol (IPA, Wako) was used to homog- enize the organic and aqueous phases during the gel prepa- ration. In this synthesis method silicon alkoxides were first hydrolyzed with the alkaline template solution followed by the addition of titanium alkoxide and subsequent dilution, alcohol removal, aging and hydrothermal treatment at an elevated temperature. In a typical synthesis of Cl-propyl- methyl-Ti-MCM-41 18.2 g of CTMABr was dissolved in a mixture of 50 g H 2 O and 45 g IPA. To it solution A, consisting of 7.3 g 3-chloropropyldimethoxy methylsilane (ClPDMMS) and 33.5 g TEOS, and solution B, consisting of 36.4 g TMAOH and 18 g H 2 O, were added together at once and the mixture was stirred vigorously at room tem- perature for 1 h. After 1 h, 2.3 g TBOT dissolved in 10 g IPA was added dropwise to the resultant clear solution and the stirring was continued for 1 h. Then the solution was heated at 353 K for 1 h to remove the added alcohols and those produced during the hydrolysis of the alkoxides (oth- erwise the presence of alcohols promotes the dissolution of micelles). Finally, the volume of the solution was ad- justed with water. This gel was aged overnight (24 h) with continuous stirring. Finally, the pH of the resultant gel  J.C. Baltzer AG, Science Publishers