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General organic chemistry reaction mechanisms
This map summarizes in detail the reaction mechanisms of organic chemistry such as elementary reactions and reaction mechanisms, active intermediates and transition state structures, free radical reactions, elimination reactions, nucleophilic reactions, etc.
Edited at 2021-11-13 18:27:44- One Hundred Years of Solitude Character Relationship Chart
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
- One Hundred Years of Solitude Character Relationship Chart
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
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Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
General organic chemistry reaction mechanisms
- One Hundred Years of Solitude Character Relationship Chart
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
- One Hundred Years of Solitude Character Relationship Chart
One Hundred Years of Solitude is the masterpiece of Gabriel Garcia Marquez. Reading this book begins with making sense of the characters' relationships, which are centered on the Buendía family and tells the story of the family's prosperity and decline, internal relationships and political struggles, self-mixing and rebirth over the course of a hundred years.
- Project Management Process Template
Project management is the process of applying specialized knowledge, skills, tools, and methods to project activities so that the project can achieve or exceed the set needs and expectations within the constraints of limited resources. This diagram provides a comprehensive overview of the 8 components of the project management process and can be used as a generic template for direct application.
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General organic chemistry reaction mechanisms
Elementary reactions and reaction mechanisms
Reaction mechanism (classification)
free radical reaction
free radical addition
free radical substitution
ionic reaction
Electrophilic bonus
electrophilic substitution
elimination response
nucleophilic addition
nucleophilic substitution
synergistic reaction
Elementary reaction (elementary reaction)
A reaction in which reactant molecules can be directly converted into product molecules in a collision
Only elementary reactions obey the law of mass action
divided into
Chain trigger
chain growth
chain termination
Heat of reaction and activation energy
State function, which only represents the energy difference between reactants and products
Breaking covalent bonds absorbs energy, forming covalent bonds releases energy
Through dissociation, it can be calculated: E anti-E generation (front-back)
The heat of reaction determines the direction and trend of the reaction Activation energy determines reaction speed
Active intermediates and transition state structures
reaction classification
No reactive intermediates experienced: synergistic reaction (completed in one step)
After two or more steps of intermediates
Transition state is imaginary Reactive intermediates are real
Active intermediates
carbon radical
form
Produced by homolytic cleavage of covalent bonds, neutral, uncharged
There are only 7 electrons around the carbon in the center of the free radical, less than an octet. It is an electron-deficient active intermediate and is electrophilic.
structure
Planar configuration: sp2 hybridization
Pyramid configuration: sp3 hybridization
stability
in conclusion:
The easier free radicals are to form, the more stable they are
The greater the number of alkyl substitutions, the more stable the free radical formed.
The greater the conjugation strength, the more stable the free radical is.
The greater the hyperconjugation strength, the more stable the free radical is.
carbocation
form
Produced by the heterolysis of covalent bonds and the loss of bonding electrons, carbocations are extremely unstable and have a very short existence time.
The carbon atom in the carbocation has only 6 bonding electrons, lacks electrons, is electrophilic, and is easy to react with nucleophiles.
structure
Planar configuration: sp2 hybrid (most)
Pyramid configuration: sp3 hybridization
stability
Carbocations lack electrons, and any group that increases the electron density of the central atom can make it more stable.
electronic effect
induction effect
conjugation effect
hyperconjugation effect
spatial effect
C is connected to three large groups and converted from sp3 to sp2, which reduces the repulsive force between substituents and facilitates the formation of carbocations.
rearrange
Designed to form more stable carbocations
carbanion
form
It is produced by heterolytic carbon capturing two bonding electrons, usually under strong alkali conditions.
structure
Most of them are sp3 hybridized and have a triangular pyramid shape.
stability
Anything that can produce conjugation effects and electron-withdrawing effects on carbanions, and can disperse the charge of the central carbon atom of carbanions, can stabilize it.
The alkyl group is an electron-donating group. The more carbanions are connected to the alkyl group, the more unstable it will be (negative charge concentration).
The more s components in the orbit where the negative charge is located in the carbanion (the charge is closer to the nucleus, the lower the energy), the more stable it is
Bond polarity and reaction forms
Nucleophile Nu-
electron pair donor
Classification
Negative ions
Such as: HO-, RO-, CN-, X-, etc.
Lewis base
Such as: H2O, NH3, ROH, etc.
Alkenes and aromatics (easy to react with positive ions or electron-deficient molecules)
Nucleophile E
electron pair acceptor
Classification
cation
polar molecules
Such as: hydrogen halide, halogenated hydrocarbon, acid halide, carbonyl compound
Polarizable neutral molecules
Such as: Cl2, Br2
Lewis acid
Such as: BF3, ZnCl2, etc.
oxidizing agent
Such as: organic peroxyacid
No octet electron reagent
transition state structure
Classification (three categories)
subtopic
Hammond hypothesis
In a simple elementary reaction, the structure and energy of the transition state of this step are similar to those of the closer one.
subtopic
free radical reaction
generation of free radicals
illumination
Thermal cracking
One electron redox reaction
free radical substitution reaction
Such as: halogenation reaction of methane
*Delay in the presence of O2 O2: free radical inhibitor
Reaction rate: F2>Cl2>Br2>I2
Among them: F2 is too violent and difficult to control I2 does not react: even if it reacts, its reverse reaction is easy to proceed
Selectivity of halogenation reactions
free radical addition reaction
distinguish
Electrophilic addition: Markov's rule: When HX is added to an alkene, H is attached to C with fewer alkyl substituents; X is attached to C with more alkyl substituents.
Free Radical Addition: Anti-Markov's Rule Conditions: presence of peroxide Also known as peroxide effect, or Karasch effect
The Karasch effect is limited to HBr (HCl and HI will undergo electrophilic addition regardless of the presence or absence of peroxide, complying with Markov's rule)
elimination response
Haloalkane single molecule (E1)
beta-elimination reaction
Zaitsev's rule (main): Prioritize elimination to produce alkenes with many substituents on the double bond
Hofman's rule: Large bases preferentially attack H on C with small steric hindrance.
When the product has cis-trans isomerism, the stable E-type product is the main one.
Haloalkyl bimolecule (E2)
Generally, it is a Zaitsev product; when the volume and intensity of the alkaline reagent increase, a Hoffman product will be generated The two eliminated groups must be in trans coplanar positions, and the products are mainly stable E-type products.
Single molecule conjugation elimination reaction (E1CB)
Alkyl fluorides are special, and their elimination produces alkenes with fewer substituents.
alcohol
Under acid catalysis, the dehydration of secondary, tertiary, and primary alcohols (except ethanol) follows the E1 process.
Hofman elimination of quaternary ammonium salts
Hofman elimination is affected by steric hindrance and always generates small molecular olefins.
Eliminate addition reactions
, first eliminate, then add
Nucleophilic reaction
nucleophilic addition
Only found in alkynes, carbonyl, and cyclic ether compounds
Alkynes
C-ion stability is given priority and follows Markov’s rule
Carbonyl group (can be used in both acid and alkali environments)
a. With Grignard reagent (RMgX)
b. With amines
c. With water (generating geminal glycol, most of which are unstable)
d. With alcohol
Influencing factors: The nucleophilicity of nucleophiles How electrophilic is the carbonyl carbon atom? Steric effects around the carbonyl group
cyclic ethers
Acidic ring opening
Alkaline ring opening
nucleophilic substitution
C-X's cleavage: Self-cleavage & heterolysis under the action of nucleophiles
Single molecule nucleophilic substitution of haloalkanes (SN1) (e.g.: tert-butyl bromide)
SN1 mechanism: The C-X bond dissociates first and then forms a bond with the nucleophile (two-step mechanism, mainly considering C stability)
Rearrangements may occur due to the stability of C ions
Haloalkyl bimolecular nucleophilic substitution (SN2) (e.g.: methyl bromide)
SN2 mechanism: dissociation of old bonds and formation of new bonds occur simultaneously (one-step mechanism, mainly considering steric hindrance)
As the hydrocarbon groups on β-C increase, the SN2 reaction rate decreases.
Alcohol (thiol-containing) affinity halogenation reaction
with hydrohalic acid
Lucas reagent: (concentrated) HCl (anhydrous) ZnCl2, ZnCl2 as catalyst
If it is a tertiary alcohol, proceed according to SN1
with halogenated compounds
Features: No rearrangement products (no C intermediate, non-SN1 mechanism)
Nucleophilic substitution of ethers
Mixed ether reaction orientation: C High stability: SN1 (such as: tertiary alcohol) Small steric hindrance: SN2 (such as: primary alcohol, alkyl carbon is directly connected to O)
Nucleophilic substitution of aromatic rings
It is better to have electron-withdrawing groups at the ortho and meta positions of the leaving group.
electrophilic reaction
Electrophilic addition: Heterolysis produces positively charged groups (electrophiles) that attack unsaturated bonds
Alkenes
①Conform to Markov’s rules ②The addition of water, inorganic acids, organic acids, alcohols, phenols and alkenes proceeds according to the carbocation intermediate mechanism; there are rearrangement products in both cis and trans ways. ③ Halogens (Br, Cl), hypochlorous acid, etc. proceed according to the cyclocationic intermediate mechanism, which is a trans addition without rearrangement.
Alkynes
Similar to alkenes, can electrophilically add to polar reagents
Alkenes are more susceptible to electrophilic addition than alkynes
Classification
with hydrogen halide
with halogen
with H2O
electrophilic substitution
reaction mechanism
① Halogenated
②Nitrification
③Sulfonation
④Alkylation
⑤Acylation (acid anhydride is acylation reagent)