MindMap Gallery Alkenes
A summary of the knowledge of olefins in university organic chemistry. Its structure is a carbon-carbon double bond (sp2 hybridization) and the general formula (CnH2n). It shares the knowledge of ethylene. This picture was drawn by hand.
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This is a mind map about bacteria, and its main contents include: overview, morphology, types, structure, reproduction, distribution, application, and expansion. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about plant asexual reproduction, and its main contents include: concept, spore reproduction, vegetative reproduction, tissue culture, and buds. The summary is comprehensive and meticulous, suitable as review materials.
This is a mind map about the reproductive development of animals, and its main contents include: insects, frogs, birds, sexual reproduction, and asexual reproduction. The summary is comprehensive and meticulous, suitable as review materials.
Alkenes
structure
carbon carbon double bond
sp2 hybridization method
2 p orbitals are hybridized, leaving only one p orbital
general formula
CnH2
Ethylene
Π key
Features
Low energy, unstable, cannot exist alone
No axial symmetry, no free rotation
Electronic cloud is more liquid
isomerism
Carbon chain isomerism: 1-butene and methylpropyl
Functional group positional isomerism
stereoisomerism
cis-trans isomerism
Generate conditions
There are factors that limit rotation: such as double bonds, rings
The two groups to which the carbon atoms of the double bond are attached must be different.
Naming method
systematic nomenclature
cis-trans notation
chemical properties
Electrophilic bonus
Principle: Πelectrons are vulnerable to attack by electrophiles
Electrophile: A reagent lacking electrons
Addition with halogen
Addition with bromine water and chlorine gas
Bromium ion trans addition
Addition with hydrogen halide (Markovitch)
The reason why the bonus complies with Markov’s rules
electronic effect
induction effect
Methyl is an electron donating group
F3C- is a strong electron-withdrawing group
hyperconjugated system
Stability Comparison of Carbocations
tert>secondary>primary>methyl
rearrangement of carbocation
peroxidation effect
In the presence of peroxide, anti-horse reaction occurs (only HBr has this reaction)
Concentrated sulfuric acid (Martens)
Mahalanobis
Reaction with halogen aqueous solution
Markov trans addition
Add water (Marshes)
Mahalanobis
Hydroboration-oxidation reaction
Features
anti-horse
No carbocation is generated and no rearrangement products are produced
cis addition
Hydroxymercurylation-Demercury Reaction
Mahalanobis not rearranged
dimerization reaction of olefins
hydrogenation
Catalytic hydrogenation
cis
Hydrogenation reaction exothermic
The higher the heat of hydrogenation, the more unstable the olefin is. Cis olefins have higher heat of hydrogenation and lower stability
oxidation reaction
Epoxidation reaction (reagent peroxyacid) cis oxidation
potassium permanganate
Alkaline, neutral (cis addition)
acidic, heated
generate oxygen-containing compounds
Ozonation (ozone, Zn powder, water) generates aldehydes or ketones
subtopic
Catalytic oxidation (reaction using oxygen or air as oxidant under the action of a catalyst)
Alkene a-hydrogen reaction
Halogenation reaction (substitution reaction; reaction conditions: high temperature or light)
Remember: NBS
Methods for preparing olefins
Dehydrogenation of halogenated hydrocarbons (reaction conditions: KOH/ROH, dehydrogenation on carbon atoms with less hydrogen)
subtopic
Alcohol dehydration (concentrated sulfuric acid, heating)
subtopic
Dehalogenation of o-dihalocarbons