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6098004 
Journal Article 
RADIOCHEMISTRY OF ALCOHOLS .20. UV PHOTOLYSIS (LAMBDA =185 NM) OF TERT-BUTANOL-CYCLOHEXANE MIXTURES 
Schuchmann, HP; Vonsonntag, C; Schultefrohlinde, D 
1975 
0 
Journal of Photochemistry
ISSN: 0047-2670
EISSN: 1873-2658 
4 
1-2 
63-74 
English 
WOS:A1975W127400005 
Dilute solutions of t-butanol (0.04 to 1.16 mol/l) in cyclohexane were photolyzed at 185 and 193 nm. At 185 nm and a concentration of 0.91 mol/1 the following quantum yields were measured: hydrogen, 0.60; cyclohexene, 0.280; bicyclohexyl, 0.246; t-butyl cyclohexyl ether, 0.058; methane, 0.076; acetone, 0.070; isobutene oxide, 0.029; cyclohexanol, 0.0030; methylcyclohexane, 0.0073; cyclohexyl dimethyl carbinol, 0.0053; ethylene, 0.0010; ethane, 0.0004; isobutene, 0.006; isobutane, 0.001. The quantum yields of methane, acetone, methylcyclohexane, and cyclohexyl dimethyl carbinol increase with increasing t-BuOH concentration while those of ethylene and ethane decline and those of the other products are essentially unaffected in the concentration range investigated. The quantum yields increase slightly with temperature. Photolysis at 193 nm leads to the same H2/CH4 ratio as is obtained at 185 nm. A reaction scheme is developed which in conjunction with material balance considerations leads to the quantum yields of the primary fragmentation steps of the excited t-butanol molecule. Extinction coefficients of t-BuOH/cyclohexane mixtures have been measured and found to increase with falling t-BuOH concentration, from 90 l mol−1 cm−1 in neat t-BuOH to a value of about 450 l mol−1 cm−1 (at 185 nm) at very low concentrations. This behaviour reflects the existence of different states of association of the BuOH molecules in the solutions, which are believed to be the cause of the concentration dependence of the quantum yields.