Alkenes Flashcards
Definition
unsaturated hydrocarbons: degree of unsaturation depend on number of rings/multiple bonds
Stereoisomers
- Distributed Alkenes: cis and trans
2. Trisubstituted/tetrasubstituted: Zusammen and Entegen
Stability of Alkenes
cis alkenes are less stable than their trans isomers because of steric strain between the two larger substituents
Markovnikov Orientation
if an alkene reacts with HX, the X attaches to the C with the more alkyl substituents
Hydrohalogenation
Alkyne + HX –> trans alkene
trans alkene + HX –> geminal halide (geminal:gemini: twins)
Hydrohalogenation
ionic mechanism, carbocation as an intermediate
alkene + X2 –> alkyl halide
Halogenation
Alkene + X2 –> trans/vicinal dihalide (antiaddition)
Halohydrin Formation
Alkene + X2 in H2O –> Halohydrin + HX
Hydroboration-oxidation
Alkyne –> ketone
if TERMINAL Alkyne –> aldehyde
Lindlar’s Catalyst
P-2 or metallic Pd deposited in CaCO3
Oxidative Cleavage
- Ozonolysis
2. Oxidation in KMnO4
Ozonolysis
Alkene + O3 –> Aldehydes
Oxidation in KMnO4
+hot +basic +KMnO4 –> carboxylic acids
Acid-Catalyzed Hydration
Alkene + water + acid –> Alcohol w/ OH @ 2* C
Alcohol w/ OH @ 2* C –> shifting –> Alcohol w/ OH @ 3* C
Oxymercuration/Demercuration
Markovnikov’s, no rearrangement, racemic
Cyclo alkene with substituent + Hg(OAc), H2O/THF + NaHB4 –>
breaking of double bond + addition of OH and H at 2 carbons previously in double bond
