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Sonochemistry of Selected Hydrocarbons, Sulfur-Containing

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Sonochemistry of Selected Hydrocarbons, Sulfur-Containing Sonochemistry of Selected Hydrocarbons, Sulfur-containing and Nitrogen-containing Organic Compounds in Aqueous Solutions and Nonaqueous Liquids Dissertation Zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakultät der Friedrich-Schiller-Universität Jena von Dipl. Chem. (Umweltchemie) Zhi-Lin Wu geboren am 30. Juli 1965 in Zhenjiang, Jiangsu Provinz von China. Gutachter: 1. 2. Tag der öffentlichen Verteidigung: I Contents 1 Introduction ........................................................................................................... 1 2 Theoretical Part ..................................................................................................... 4 2.1 Ultrasound.............................................................................................................. 4 2.2 Acoustic Cavitation................................................................................................ 4 2.3 Mechanisms and Sites of Sonochemical Reactions............................................... 6 2.3.1 Mechanisms of Sonochemical Reactions....................................................... 6 2.3.2 Sites of Sonochemical Reactions ................................................................... 8 2.4 Kinetics of Sonochemical Reactions ..................................................................... 9 2.5 Sonochemistry of Organic Compounds in Aqueous Solutions ........................... 10 2.5.1 Mechanisms and Reaction Sites of Aquasonolysis...................................... 10 2.5.2 Effects of Acoustic Frequency ..................................................................... 14 2.5.3 Effects of Acoustic Power............................................................................ 16 2.5.4 Effects of the Bulk Liquid Temperature and Applied Pressure ................... 18 2.5.5 Effects of the Dissolved Gas........................................................................ 20 2.5.6 Effects of Organic Solutes ........................................................................... 22 2.5.7 Effects of pH Values of the Solutions.......................................................... 25 2.6 Sonochemistry of Organic Chemicals in Nonaqueous Liquids........................... 26 2.6.1 Roles of Vapor Pressures of Organic Liquids.............................................. 27 2.6.2 Ultrasonic Cleavage of Organic Liquids and Radical Reactions ................. 27 2.6.3 Sonoluminescence and Temperatures at Hot Spots in Organic Liquids ...... 29 2.6.4 Sonolytic Rates and Kinetics of Organic Liquids ........................................ 30 3 Experimental Part................................................................................................ 32 3.1 Chemicals............................................................................................................. 32 3.2 Ultrasound Devices and Operating Conditions ................................................... 33 II 3.2.1 Ultrasound Setup for Aqueous Solutions..................................................... 33 3.2.2 Ultrasound Setup for Nonaqueous Solutions ............................................... 34 3.3 Ultrasonic Power Measurement........................................................................... 35 3.4 Analysis ............................................................................................................... 36 3.4.1 Sampler ........................................................................................................ 36 3.4.2 Gas Chromatography ................................................................................... 37 3.4.3 UV/Vis Analysis of DPPH........................................................................... 38 4 Results of Sonolyses of Volatile Organic Substrates in Aqueous Solutions....... 39 4.1 Aquasonolyses of Selected C6HX Hydrocarbons................................................. 39 4.1.1 Aquasonolytic Rate Constants of Selected Cyclic Hydrocarbons ............... 39 4.1.2 Aquasonolytic Rate Constants of Selected Aliphatic Hydrocarbons........... 40 4.1.3 Products of Aquasonolyses of Selected C6HX Hydrocarbons...................... 40 4.2 Formation of Benzene during Aquasonolyses of the Selected C6HX Hydrocarbons ...................................................................................................... 47 4.2.1 Yield and Selectivity of Benzene during Aquasonolyses ............................ 47 4.2.2 Effect of the Initial Concentration on the Yield of Benzene........................ 49 4.2.3 Comparisons of Selectivity between Benzene and Other C6 Products during the Aquasonolysis of 1,3-Cyclohexadiene ....................................... 49 4.3 Aquasonolyses of Thiophene and Its Derivatives................................................ 50 4.3.1 Aquasonolytic Rate Constants of Thiophene and Its Derivatives................ 51 4.3.2 Products from Aquasonolyses of Selected Thiophenes ............................... 52 4.4 Aquasonolyses of Thioethers............................................................................... 55 4.4.1 Aquasonolytic Rate Constants of Thioethers............................................... 55 4.4.2 Products from Aquasonolyses of the Selected Thioethers........................... 56 4.5 Aquasonolyses of N-Heterocyclic Compounds................................................... 58 4.5.1 Aquasonolytic Rate Constants of the Selected N-Heterocycles .................. 59 4.5.2 Products from Aquasonolyses of the Selected N-Heterocycles................... 60 5 Results of Sonolyses of Volatile Organic Substrates in Nonaqueous Liquids................................................................................................................. 61 III 5.1 Sonolyses of Aliphatic and Cyclic C6HX Hydrocarbons ..................................... 61 5.1.1 Sonolyses of the Selected C6HX Hydrocarbons at Normal Temperature..... 61 5.1.2 Sonolyses of the Selected Aliphatic C6HX Hydrocarbons at Low Temperature ................................................................................................. 61 5.1.3 Sonolyses of the Selected Cyclic C6HX Hydrocarbons at Low Temperature ................................................................................................. 67 5.2 Sonolytic Products of Selected Cyclic C6HX Hydrocarbons in Nonaqueous Solutions.............................................................................................................. 71 5.2.1 Formation of Benzene during Sonolyses of Cyclohexene and Cyclohexadiene in Organic Solvents ........................................................... 71 5.2.2 Secondary Reactions Occurring during Sonolyses of Cyclohexene and Cyclohexadiene in Tetrachloroethylene....................................................... 73 5.2.3 Secondary Reactions Occurring during Sonolyses of Benzene and Cyclohexane in Tetrachloroethylene............................................................ 73 5.3 Sonolytic Products of Pure Thioethers ................................................................ 75 5.4 Sonolytic Products of Pure Thiophene and Its Derivatives ................................. 77 5.5 Sonolytic Products of N-Heterocycles................................................................. 80 6 Discussion ........................................................................................................... 84 6.1 Sonolytic Kinetics in Aqueous Solutions ............................................................ 84 6.1.1 Comparison of Aquasonolytic Rate Constants of Model Compounds ........ 84 6.1.2 Roles of Thermostability of Organic Substrates .......................................... 84 6.1.3 Roles of Henry’s Law Constant and Transfer of Substrate.......................... 86 6.1.4 Roles of Vapor Pressure of Substrate........................................................... 87 6.1.5 Roles of Hydrophobicity of Substrate on Aquasonolytic Rate Constants...................................................................................................... 89 6.1.6 Effects of Initial Concentration of Organic Substrate on the Kinetics......... 92 6.2 Sonolyses of Organic Substrates.......................................................................... 94 6.2.1 Effects of Volatility of Liquids on the Sonolytic Rates ............................... 94 6.2.2 Sonolyses of Selected C6HX Hydrocarbons at Low Temperature................ 97 6.2.3 Sonolytic Pseudo-Yields of the Selected N-Heterocycles ........................... 98 6.2.4 Effects of Ultrasonic Intensity and Density on Sonolyses of Organic Substrates ..................................................................................................... 99 IV 6.3 Roles of Lipophobicity and Volatility of Hydrocarbons on Sonolyses in Nonaqueous Solutions....................................................................................... 102 6.3.1 Effects of LogPOW of Organic Solvents on Sonolyses of the Selected C6Hx Hydrocarbons.................................................................................... 102 6.3.2 Effects of Vapor pressures of C6Hx Hydrocarbons on Sonolytic Rates in Organic Solvents.................................................................................... 103 6.4 Sonochemical Mechanisms of Selected Organic Substrates ............................. 104 6.4.1 Sonolyses of C6HX Hydrocarbons.............................................................
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