Unimolecular Elimination Reactions
CHEM 206- ORGANIC CHEMISTRY
EXP 10-UNIMOLECULAR ELIMINATION REACTIONS
Cansın Etli
Lab Instructor: Emel Yılgör
Experiment date:06.12.2010
Report Date: 20.12.2010
ABSTRACT
In this experiment, the purpose was to investigate E1 elimination mechanism with the reaction of cyclohexanol to cyclohexene. The reaction was acid catalyzed dehydration of alcohol and with catalyst sulfuric acid cyclohexene was obtained from cyclohexanol. And the product was obtained from the simple distillation and later it was reacted with bromine and potassium permanganate. The observations and results were all recorded. Simple distillation was used for distillation technique, and the distillate was seperated into test tubes, and to the one of them, bromine was added, and to the another potassium permanganate was added. Permanganate’s color changed from purple to brown, and bromium’s color changed brown to colorless, it became color solution which was light yellow.
INTRODUCTION
One of the most useful and general methods of preparing alkenes or olefins is based on the dehydration of alcohols with acids. Strong acids such as sulphuric and phosphoric acids are required to form the oxonium ion from which the hydronium ion is eliminated.
“This cyclohexene from cyclohexanol reaction belongs to a broad class of organic transformations called elimination reactions, and within that class, this E1 elimination reaction constitutes another of the cornerstone reactions of organic chemistry. Mechanistically related to the SN1 reaction, the E1 often competes with attempted substitution.” (5) Through proper choice of reaction conditions, it can usually be made the predominant or exclusive pathway. For example, one of the principal ways to prepare alkenes is via the acid catalyzed dehydration of an alcohol
Dehydration of Alcohols - Zaitsev • When an alcohol has two or three ( carbons, dehydration is regioselective
EXP 10-UNIMOLECULAR ELIMINATION REACTIONS
Cansın Etli
Lab Instructor: Emel Yılgör
Experiment date:06.12.2010
Report Date: 20.12.2010
ABSTRACT
In this experiment, the purpose was to investigate E1 elimination mechanism with the reaction of cyclohexanol to cyclohexene. The reaction was acid catalyzed dehydration of alcohol and with catalyst sulfuric acid cyclohexene was obtained from cyclohexanol. And the product was obtained from the simple distillation and later it was reacted with bromine and potassium permanganate. The observations and results were all recorded. Simple distillation was used for distillation technique, and the distillate was seperated into test tubes, and to the one of them, bromine was added, and to the another potassium permanganate was added. Permanganate’s color changed from purple to brown, and bromium’s color changed brown to colorless, it became color solution which was light yellow.
INTRODUCTION
One of the most useful and general methods of preparing alkenes or olefins is based on the dehydration of alcohols with acids. Strong acids such as sulphuric and phosphoric acids are required to form the oxonium ion from which the hydronium ion is eliminated.
“This cyclohexene from cyclohexanol reaction belongs to a broad class of organic transformations called elimination reactions, and within that class, this E1 elimination reaction constitutes another of the cornerstone reactions of organic chemistry. Mechanistically related to the SN1 reaction, the E1 often competes with attempted substitution.” (5) Through proper choice of reaction conditions, it can usually be made the predominant or exclusive pathway. For example, one of the principal ways to prepare alkenes is via the acid catalyzed dehydration of an alcohol
Dehydration of Alcohols - Zaitsev • When an alcohol has two or three ( carbons, dehydration is regioselective
References: 1. http://spot.pcc.edu/~chandy/241/cyclohexanollab.pdf 2. http://74.125.77.132/search?q=cache:_Cqr_yGE-fEJ:course1.winona.edu/tnalli/fall05/lec33.ppt+alcohol+dehydration+E1&hl=tr&ct=clnk&cd=10&gl=tr&client=firefox-a 3. http://www.chemguide.co.uk/organicprops/alcohols/dehydration.html 4. http://www.chemistrydaily.com/chemistry/Elimination_reaction 5. http://www.utdallas.edu/~scortes/ochem/OChem1_Lecture/Class_Materials/15_rel_sn1_e1.pdf 6. http://en.wikipedia.org/wiki/Cyclohexene 7. http://en.wikipedia.org/wiki/Sulfuric_acid 8. http://en.wikipedia.org/wiki/Cyclohexanol 9. Fall 2008, Chem 206-Organic Chemistry Lab Manual