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11.15 Preparation of Alkenylbenzenes. dehydrogenation dehydration dehydrohalogenation. CH 2 CH 3. CH. CH 2. Dehydrogenation. industrial preparation of styrene 11,800,000,000 lbs. produced in U.S. in 1999. 630°C. ZnO. + H 2. Cl. Cl. CH. CHCH 3. CH 2. OH.
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11.15Preparation of Alkenylbenzenes • dehydrogenation • dehydration • dehydrohalogenation
CH2CH3 CH CH2 Dehydrogenation • industrial preparation of styrene • 11,800,000,000 lbs. produced in U.S. in 1999. 630°C ZnO + H2
Cl Cl CH CHCH3 CH2 OH Acid-Catalyzed Dehydration of Benzylic Alcohols KHSO4 heat + H2O (80-82%)
Cl Cl CH CHCH3 CH2 OH Cl CHCH3 + Acid-Catalyzed Dehydration of Benzylic Alcohols KHSO4 heat (80-82%)
CH2CHCH3 H3C Br CH H3C CHCH3 Dehydrohalogenation NaOCH2CH3 ethanol, 50°C (99%)
11.16Addition Reactions of Alkenylbenzenes • hydrogenation • halogenation • addition of hydrogen halides
CH3 CH3 C CHCH2CH3 CHCH3 H2 Pt Br Br Hydrogenation (92%)
CH CH2 Halogenation Br2 CH CH2 Br Br (82%)
Cl HCl Addition of Hydrogen Halides (75-84%)
Cl HCl Addition of Hydrogen Halides + via benzylic carbocation
CH CH2CH2Br CH2 Free-Radical Addition of HBr HBr peroxides
CH CH2CH2Br CH2 Free-Radical Addition of HBr HBr peroxides CH CH2Br • via benzylic radical
H2C CHC6H5 CH2 CH CH2 CH CH2 CH C6H5 C6H5 C6H5 Polymerization of Styrene polystyrene
• • • H2C CHC6H5 Mechanism •• RO
• • Mechanism •• RO H2C CHC6H5 •
• • H2C CHC6H5 Mechanism •• RO H2C CHC6H5 •
• • • H2C CHC6H5 Mechanism •• RO H2C CHC6H5
• • Mechanism •• RO H2C CHC6H5 H2C CHC6H5 •
• • H2C CHC6H5 Mechanism •• RO H2C CHC6H5 H2C CHC6H5 •
• • • H2C CHC6H5 Mechanism •• RO H2C CHC6H5 H2C CHC6H5
•• • RO • H2C CHC6H5 H2C CHC6H5 H2C CHC6H5 Mechanism •
•• • RO • H2C CHC6H5 H2C CHC6H5 H2C CHC6H5 H2C CHC6H5 Mechanism •
•• • RO • H2C CHC6H5 H2C CHC6H5 H2C CHC6H5 H2C CHC6H5 Mechanism •