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Nucleophilic Substitution Reactions - SN1 and SN2 Mechanism, Organic Chemistry
 
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This organic chemistry video tutorial explains how nucleophilic substitution reactions work. It focuses on the SN1 and Sn2 reaction mechanism and it provides plenty of examples and practice problems. The Sn2 reaction is a second order nucleophilic substitution reaction where the rate is dependent on the concentration of the substrate / alkyl halide and the nucleophile. SN2 reactions occur with inversion of configuration and work well with methyl and primary substrates. It's a concerted reaction mechanism that occurs in a single step. The rate law for the SN1 reaction is given as well. SN1 reactions proceed via a carbocation intermediate and carbocation rearrangements such as the hydride shift and the methyl shift are possible. SN1 reactions work well with tertiary alkyl halide substrates due to carbocation stability. Carbocations are stabilized by means of hyperconjugation and the inductive effect. SN1 reactions will produce an unequal racemic mixture. The stereochemistry of both reaction mechanisms are discussed in detail. SN1 reactions work well with polar protic solvents but SN2 reactions work better in polar aprotic solvents. Solvolysis reactions are sn1 reactions where the nucleophile is the same as the solvent.
Electrophillic Aromatic Substitution
 
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Electrophilic Aromatic Substitution is one thing that benzene does. The mechanisms are getting trickier, no? Don't worry, practice makes perfect. From halogenation to Friedel-Crafts alkylation, this is a handy family of reactions. Subscribe: http://bit.ly/ProfDaveSubscribe [email protected] http://patreon.com/ProfessorDaveExplains http://facebook.com/ProfessorDaveExplains http://twitter.com/DaveExplains http://instagram.com/DaveExplains General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Organic Chemistry Tutorials: http://bit.ly/ProfDaveOrgChem Biochemistry Tutorials: http://bit.ly/ProfDaveBiochem Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 Modern Physics Tutorials: http://bit.ly/ProfDavePhysics2 Mathematics Tutorials: http://bit.ly/ProfDaveMaths Biology Tutorials: http://bit.ly/ProfDaveBio American History Tutorials: http://bit.ly/ProfDaveAmericanHistory
Nucleophilic Aromatic Substitution Reaction Mechanism - Meisenheimer Complex & Benzyne Intermediate
 
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This organic chemistry video tutorial discusses the mechanism of nucleophilic aromatic substitution reactions. The first type involves a resonance stabilized carbanion intermediate known as the meisenheimer complex which is formed whenever the Benzene ring derivative contains a strong electron withdrawing group such as a nitro group which activates the ring toward SnAr reactions. The Benzyne intermediate occurs when there are no strong electron withdrawing groups present. A strong base / nucleophile such as NaNH2 is needed which will produce an aniline derivative. The benzyne intermediate pathway is an elimination-addition reaction where as the pathway that proceeds through the meisenheimer complex is an addition elimination reaction. This video contains plenty of examples and practice problems.
Nucleophilic Substitution Reaction - WJEC A Level Experiment
 
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To prepare a pure sample of butan-1-ol from 1-bromobutane and sodium hydroxide. Filmed at Olchfa School. Music - Straight by Bensound.
Views: 4078 SpaceyScience
7. Nucleophilic Substitution Tools - Stereochemistry, Rate Law, Substrate, Nucleophile
 
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Freshman Organic Chemistry II (CHEM 125B) SN2 substitution provides an example of establishing the mechanism of a chemical reaction by disproving all the alternatives. Five general pathways are envisioned (two-step involving either pentavalent or trivalent carbon intermediates, and one-step). They can be discriminated by applying a variety of experimental tools including stereochemistry (Walden inversion), rate law (second order and pseudo first order), and the variation of rate constant with changes in the substrate (steric hindrance and ring strain), and with changes in nucleophile or leaving group. Classic experiments by Kenyon and Phillips and by Bartlett and Knox established the nature of Walden inversion. 00:00 - Chapter 1. "Proving" a Mechanism by Imagining and Disproving All the Alternatives 06:03 - Chapter 2. Kenyon and Phillips Pinpoint Backside Attack in Nucleophilic Substitution 18:56 - Chapter 3. Using Kinetics to Study Mechanisms -- Rate Law 25:47 - Chapter 4. Rate Constant -- the Influence of Substrate Structure 25:47 - Chapter 5. Rate Constant -- the Influence of Nucleophile and Leaving Group Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu This course was recorded in Spring 2011.
Views: 5040 YaleCourses
SN1, SN2, E1, & E2 Reaction Mechanism Made Easy!
 
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This video shows you an easy way to identify if a reaction will undergo an SN1, SN2, E1, or E2 mechanism. SN1 reactions generate a racemic mixture of stereoisomers due to the planar structure of its carbocation. Both SN1 and E1 reactions can rearrange by means of a hydride shift or a methyl shift due to the formation of carbocation intermediate. There are no rearrangements for an SN2 and E2 reaction mechanism. Those reactions are concerted meaning they occur simultaneously in 1 step. SN2 reactions proceed with inversion of stereochemistry and E2 reactions proceed via an anti-coplanar transition state which means that the hydrogen that you remove must be opposite to the bromine before you can create an alkene. SN2 reactions prefer methyl & primary substrates. SN1 & E1 reactions prefer secondary and tertiary substrates. E2 requires the use of a strong base. Polar Protic Solvents favor SN1/E1 reactions because they can stabilize the carbocation intermediate by solvation. They're not good for SN2 reactions because they solvate/stabilize the nucleophile which affects the rate of an SN2 reactions (Rate = K[Substrate][Nucleophile]). SN1 reactions are not affected by the concentration or strength of the nucleophile due to the equation Rate = K[Substrate]. Polar aprotic solvents work well for an SN2 reaction because they do not solvate the nucleophile allowing to react freely with the substrate. Crown ethers enhance the strength of the nucleophile because they solvate the cation such as K+ allowing the nucleophile such as F- to be free to react. I hope these extra notes help :) New SN1 SN2 E1 E2 Video - Updated! https://www.youtube.com/watch?v=pKJ0z7N6W5w Organic Chemistry Video Playlist: https://www.youtube.com/watch?v=n5vjCqnVb6s&index=1&t=25s&list=PL0o_zxa4K1BU3gxU8RwqkEET2ilZ80Znj Access to Premium Videos: https://www.patreon.com/MathScienceTutor Facebook: https://www.facebook.com/MathScienceTutoring/
SN2 Reactions | University Of Surrey
 
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Rate determining step - SN2 reactions. A-Level Chemistry teaching/revision resource
Views: 122673 University of Surrey
Electrophilic Aromatic Substitution Reactions Made Easy!
 
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This organic chemistry video tutorial provides a basic introduction into electrophilic aromatic substitution reactions. Here is a list of reactions covered in this video: 1. Friedel Crafts Alkylation of Benzene 2. Bromination of Ethylbenzene 3. Aromatic Nitration of Benzene followed by Bromination of Nitrobenzene 4. Polyalkylation Using Friedel Crafts Alkyation 5. Chlorination of a Disubstituted Benzene Derivative 6. Sulfonation of para-methylphenol. 7. Steric Effects and Directing Effects of Disubstituted Benzene Derivatives 8. Friedel Crafts Aklyation Reaction and Strongly Deactivating Groups 9. Synthesis of Benzoic Acid From Benzene 10. Side Chain Oxidation Using Chromic Acid 11. Synthesis of Aniline From Benzene 12. Synthesis of Benzaldehyde From Benzene Using The Gatterman Koch Reaction 13. Synthesis of Propyl Benzene Using the Friedel Crafts Acylation Reaction Followed by the Clemmensen Reduction Reaction. 14. Synthesis of Toluene From Bromobenzene Using an Organocuprate Reagent / Gilman Reagent 15. Synthesis of meta-iodobenzenesulfonic acid 16. Synthesis of para-nitrobenzoic acid 17. Synthesis of meta-chloroaniline 18. Synthesis of para-nitroaniline 19. Protecting amine groups with acid chlorides by amide formation 20. Blocking Groups 21. Application of Desulfonation Reactions 22. Synthesis of a Trisubstituted Benzene Derivative Subscribe: https://www.youtube.com/channel/UCEWpbFLzoYGPfuWUMFPSaoA?sub_confirmation=1 Access to Premium Videos: https://www.patreon.com/MathScienceTutor https://www.facebook.com/MathScienceTutoring/ New Organic Chemistry Playlist https://www.youtube.com/watch?v=6unef5Hz6SU&index=1&list=PL0o_zxa4K1BXP7TUO7656wg0uF1xYnwgm&t=0s
Free Radical Substitution Reactions, Initiation Propagation Termination, NBS, Allylic Halogenation,
 
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This organic chemistry video tutorial focuses on free radical substitution reactions. It provides plenty of examples and practice problems. Here is a list of topics: 1. Free Radical Substitution Reaction Mechanisms 2. Initiation, Propagation, and Termination Steps 3. Homolytic and Heterolytic Bond Cleavage 4. Monochlorination of Methane (CH4) Reaction Mechanism 5. Primary, Secondary, and Tertiary Radicals 6. Radical Stability, Carbocation & Carbanion Stability 7. Selectivity Reactivity Principle - Potential Energy Diagrams 8. Free Radical Halogenation Reaction Mechanism 9. Radical Bromination vs Chlorination - Selective & Nonselective Reactions 10. Percent Yield Calculations of Alkyl Halide Products 11. Free Radical Halogenation of Alkanes With Br2, Cl2 and NBS 12. Electrophilic Addition of HBr to Alkenes 13. Alkene + HBr With Peroxides Reaction Mechanism 14. Alkene + NBS Reaction Mechanism 15. Allylic Bromination With NBS 16. Allylic & Benzylic Halogenation Reactions 17. Free Radical Substitution Reaction Mechanisms - Chlorination & Bromination 18. Radical Allylic Halogenation With Br2 and hv 19. Allylic and Benzylic Radicals - Stability 20. Monochlorinated Products With Stereoisomers - Identify Chirality Centers / Chiral Carbon Atoms and a plane of Symmetry 21. Constitutional Isomers and Enantiomers of Monochlorinated Alkyl Halide Products 22. Reactivity of Primary, Secondary, and Tertiary Hydrogen atoms in Free Radical Bromination and Chlorination of Alkanes 23. Free Radical Addition Reactions of HBr to Alkenes - Peroxide H2O2 or ROOR 24. Multi Step Synthesis Problems With Free Radical Substitution Reactions - Alkanes to Alkenes, Alkynes and Benzene Rings 25. Butane to 1-Butene and 2-Butene Synthesis - E2 Reaction Mechanism 26. Butane to 1-Butyne and 2-Butyne - Isomerization of Alkynes - Internal and Terminal Alkynes 27. Cyclohexane to Benzene Reaction Mechanism Synthesis Problem
Nucleophiles, Electrophiles, Leaving Groups, and the SN2 Reaction
 
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This is it! The start of the very scary reaction mechanisms! Take it easy, chief. First we will define nucleophiles, electrophiles, and leaving groups. Then, we will examine the mechanism, transition state, and stereospecificity of the SN2 reaction. Push those electrons! Learn Organic Chemistry the easy way with Professor Dave! To support this channel and keep up on STEM news at the same time, click on the link below and subscribe to this FREE newsletter: http://www.jdoqocy.com/click-9021241-13591026 Subscribe: http://bit.ly/ProfDaveSubscribe [email protected] http://patreon.com/ProfessorDaveExplains http://facebook.com/ProfessorDaveExplains http://twitter.com/DaveExplains http://instagram.com/DaveExplains General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Organic Chemistry Tutorials: http://bit.ly/ProfDaveOrgChem Biochemistry Tutorials: http://bit.ly/ProfDaveBiochem Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 Modern Physics Tutorials: http://bit.ly/ProfDavePhysics2 Mathematics Tutorials: http://bit.ly/ProfDaveMaths Biology Tutorials: http://bit.ly/ProfDaveBio American History Tutorials: http://bit.ly/ProfDaveAmericanHistory
Views: 134783 Professor Dave Explains
IB Organic Chemistry Topic 20.1 Types of organic reactions
 
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IB Organic Chemistry Topic 20.1 Types of organic reactions How to draw SN1 and SN2 reactions, and the full range of HL organic reaction mechanisms. Full resources for topic 10 are found at: http://www.mrwengibchemistry.com/topic-10-organic-chemistry.html 0:49 Nucleophilic substitution reactions SN1 SN2 1:01 Solvents 1:39 SN2 reactions 4:05 SN1 reactions 6:53 Electrophilic addition reactions 7:22 Markovnikov's rule 8:18 Electrophilic substitution reactions 9:37 Reduction reactions 9:39 Reduction reactions - alcohols 10:50 Reduction reactions - nitrobezene PPT direct link: https://mix.office.com/watch/rahiehp473ez Free online Quiz SL: http://www.proprofs.com/quiz-school/story.php?title=NjAyODE2 Free online Quiz HL: http://www.proprofs.com/quiz-school/story.php?title=NjAyODMz 20.1 Types of organic reactions HL Nucleophilic Substitution Reactions: • SN1 represents a nucleophilic unimolecular substitution reaction and SN2 represents a nucleophilic bimolecular substitution reaction. SN1involves a carbocation intermediate. SN2 involves a concerted reaction with a transition state. • For tertiary halogenoalkanes the predominant mechanism is SN1and for primary halogenoalkanes it is SN2. Both mechanisms occur for secondary halogenoalkanes. • The rate determining step (slow step) in an SN1reaction depends only on the concentration of the halogenoalkane, rate = k[halogenoalkane]. For SN2, rate = k[halogenoalkane][nucleophile]. SN2 is stereospecific with an inversion of configuration at the carbon. •SN2 reactions are best conducted using aprotic, non-polar solvents and SN1reactions are best conducted using protic, polar solvents. • Explanation of why hydroxide is a better nucleophile than water. • Deduction of the mechanism of the nucleophilic substitution reactions of halogenoalkanes with aqueous sodium hydroxide in terms of SN1and SN2 mechanisms. Explanation of how the rate depends on the identity of the halogen (ie the leaving group), whether the halogenoalkane is primary, secondary or tertiary and the choice of solvent. • Outline of the difference between protic and aprotic solvents Electrophilic Addition Reactions: • An electrophile is an electron-deficient species that can accept electron pairs from a nucleophile. Electrophiles are Lewis acids. • Markovnikov’s rule can be applied to predict the major product in electrophilic addition reactions of unsymmetrical alkenes with hydrogen halides and interhalogens. The formation of the major product can be explained in terms of the relative stability of possible carbocations in the reaction mechanism. •Deduction of the mechanism of the electrophilic addition reactions of alkenes with halogens/interhalogens and hydrogen halides. Electrophilic Substitution Reactions: • Benzene is the simplest aromatic hydrocarbon compound (or arene) and has a delocalized structure of π bonds around its ring. Each carbon to carbon bond has a bond order of 1.5. Benzene is susceptible to attack by electrophiles. • Deduction of the mechanism of the nitration (electrophilic substitution) reaction of benzene (using a mixture of concentrated nitric acid and sulfuric acid). Reduction Reactions: • Carboxylic acids can be reduced to primary alcohols (via the aldehyde). Ketones can be reduced to secondary alcohols. Typical reducing agents are lithium aluminium hydride (used to reduce carboxylic acids) and sodium borohydride. • Writing reduction reactions of carbonyl containing compounds: aldehydes and ketones to primary and secondary alcohols and carboxylic acids to aldehydes, using suitable reducing agents. • Conversion of nitrobenzene to phenylamine via a two-stage reaction. Connect with me: Facebook: https://www.facebook.com/IBChemistry2016/ Twitter: https://twitter.com/andrewweng0406 Google plus: https://plus.google.com/u/0/108611113268141564345 Pinterest: https://www.pinterest.com/mrandrewweng040/ib-chemistry/
Views: 8723 Andrew Weng
SUBSTITUTION Reactions Mechanism of  Nucleophilic SN1, SN2, SNi Organic Chemistry 2.3
 
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🙏 Please 👉SUBSCRIBE FREE 👍 & 🔔 Venus Academy Dr M V Chary ________ #chemistry4all #jee #organicchemistry ------ Next Ch2-P4/4: https://www.youtube.com/watch?v=-lXhaodTWyM&t=1148s; Grignard Reaction - Addition Reactions - Elimination Reactions - Pericyclic Reactions - Ch 2 - P4/4 --------------------- Chapter-I: Structure of Organic Molecules 1. Introduction to Organic Chemistry - How to know SP, SP2, SP3 Hybridization – Chapter 1 – Part 1 of 3. https://www.youtube.com/watch?v=ckUfVYyvnxQ 2. How Bond Length is Affected by Electronegativity and Hybridization - 5 Easy Tricks – Chapter 1- Part 2 of 3. https://www.youtube.com/watch?v=hb6bipo172Y 3. How SP, SP2, SP3 Hybridization affects - Bond angle and bond energy - 5 Easy Tips - Chapter 1 – Part 3 of 3. https://www.youtube.com/watch?v=swUbaArekK8 --------------------- Chapter-II: Reaction Mechanism and Reactivity of Organic Molecules. 4. What and How Formed Electrophiles and Nucleophiles - Reagents in Organic Synthesis- Chapter 2 - Part 1 of 4 https://www.youtube.com/watch?v=QYFHQ6NspDA 5. Friedel Crafts alkylation, acylation - Nitration - Electrophilic Aromatic Substitution -Chapter 2 - Part 2 of 4. https://www.youtube.com/watch?v=lK1cEhzIoyk 6. What are the Differences of SN1 vs SN2 - Nucleophilic Substitution Reaction Mechanism – Chapter 2 – Part 3 of 4. https://www.youtube.com/watch?v=j-3RL3Wk69U 7. Grignard Reaction - Addition Reactions - Elimination Reactions - Pericyclic Reactions – Chapter 2 – Part 4 of 4. https://www.youtube.com/watch?v=-lXhaodTWyM --------------------- Chapter-III: Electronic Displacement 8. How Acidity and Basicity Affected by Inductive Effect - Interview Organic Chemistry –Chapter 3 – Part 1 of 3. https://www.youtube.com/watch?v=5NdAFozMM38 9. Mesomeric Effect | Why Allylic Carbocation More Stable than Alkyl | Chapter 3 - Part 2 of 3. https://www.youtube.com/watch?v=E_3aZlLfO1g 10. Hyperconjugation | Keto Enol Tautomerism | Interview Organic Chemistry Tips | Chapter 3 - Part 3 of 3. https://www.youtube.com/watch?v=LzAGGNxWu4c --------------------- Nucleophilic Substitution Reactions - SN1 (Unimolecular Nucleophilic Substitution Reaction - SN2 Bimolecular Nucleophilic Substitution Reaction - SNi Intramolecular Nucleophilic Substitution Reaction - Reaction Mechanism and Reactivity of Organic Molecules - Chapter 2 - Part 3 of 4. 5 - Questions? And 12 Differences of SN1 and SN2 are Answered - Nucleophilic Substitution Reactions - SN1, SN2 and SNi – Interview Organic Chemistry. 1. Question: What is and what happens in SN1 Reaction Mechanism and how to write arrow mark? Answer: SN1 – Unimolecular Nucleophilic Substitution Reaction mechanism involves 2 stages and rate of the reaction depends on concentration of Reactant and gives Racemic mixture. In Nucleophilic Substitution reactions arrow mark must be shown from reagent nucelophile to reactant. 2. Question: What is and what happens in SN2 Reaction Mechanism? Answers: SN2 – Bimolecular Nucleophilic Substitution Reaction mechanism involves only 1 stage and rate of the reaction depends on concentration of Reactant and Reagent and gives inversion of configuration. 3. Question: What is and what happens in SNi Reaction Mechanism? Answer: SNi – Intra-molecular Nucleophilic Substitution Reaction results retention of configuration. 4. Question: What happens to stereo isomers R and S in SN1, SN2 and SNi type of reactions? Answer: 1. in SN1 reaction Racemisation takes place and - R isomer - gives - R + S racemic mixture. 2. In SN2 reaction Walden Inversion takes place - R isomer - gives - S isomer -Walden inversion . 3. In SNi reaction retention of configuration takes place - R isomer - gives - R isomer retention of configuration. 5. Question: What are differences between SN1 and SN2 reactions? Answer: There are mainly 12 differences are observed between SN1 and SN2 , they are: SN1 SN2 1. Takes place in tertiary alkyl halides 1. Primary alkyl halide 2. Two steps 2. Only one step 3. 1st slow and rate determining step 3. Only one step 4. Rate is α to concentration of alkyl halide 4. Rate is α to concentration of alkyl halide × alkali 5. Unimolecular 5. Bimolecular 6. Non-concerted 6. Concerted 7. Independent of concentration of alkali 7. Dependent on concentration of both 8. Carbo-cation intermediate is formed 8. Takes place via only transition state 9. Racemic mixture is formed provided reactant is chiral 9. Walden inversion takes place provided reactant is chiral 10. Favorable in protic solvents such as water, formic acid 10. Favorable in aprotic solvents such as dimethyl sufoxide, dimethylformamide, etc. 11. Order of reactivity: tertiary secondary primary 11. Order of reactivity: primary secondary tertiary 12. Rearrangement may takes place 12. No rearrangement takes place
Views: 678 Venus Academy
Solvent Effects on Sn1 and Sn2 Reactions
 
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Solvent Effects on Sn1 and Sn2 Reactions
Views: 237372 Khan Academy
Nucleophilic Substitution Mechanism
 
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Using the reaction between bromoethane and hydroxide ions
Views: 4881 MaChemGuy
Nucleophilic Substitution: Practice Problems
 
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Practice problem for nucleophilic substitution reactions. Problems cover SN1 and SN2 material in organic chemistry.
Views: 2697 ChemComplete
Sn2 Reactions
 
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Sn2 Reactions
Views: 515248 Khan Academy
Sn2 reactions | Substitution and elimination reactions | Organic chemistry | Khan Academy
 
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Sn2 reactions. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/organic-chemistry/substitution-elimination-reactions/sn1-sn2-sal/v/sn1-reactions-introduction?utm_source=YT&utm_medium=Desc&utm_campaign=organicchemistry Missed the previous lesson? https://www.khanacademy.org/science/organic-chemistry/substitution-elimination-reactions/sn1-sn2-sal/v/curly-arrow-conventions?utm_source=YT&utm_medium=Desc&utm_campaign=organicchemistry Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s Organic Chemistry channel: https://www.youtube.com/channel/UCNKPjijOc0WEJ7DIV_Vay3g?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
Views: 286980 Khan Academy
10.2 Nucleophilic Substitution [SL IB Chemistry]
 
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You only need to know OH- is a nucleophile (attracted to postivie charge). This will swap with the halogen in a haloalkane.
Views: 8125 Richard Thornley
Comparing the [SN1] and [SN2] Substitution Pathways
 
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http://csi.chemie.tu-darmstadt.de/ak/immel/misc/oc-scripts/animations.html?structure=sn2 This webcast gives a comparison of the two pathways for substitution at sp3 carbon. The rate-determining step and corresponding transition states are compared, along with the minimum energy pathways on a reaction coordinate diagram.
Views: 10347 jeffrey Moore
Nucleophilic Substitution, Halogenoalkane Mechanism - Organic Chem
 
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In this video we want to describe the nucleophilic substitution mechanism of halogenoalkanes or alkylhalides. There are 2 different pathways for nucleophilic substitution. SN1 Mechanism SN1 mechanism is a two step reaction. In the first step, which is the slow step, the C-Cl bond will break by itself and both electrons will go to Cl. A carbocation intermediate and Cl- ion will be formed. In the second step, which is the fast step, OH- will attack the carbocation forming the alcohol product. Based on the mechanism, we can deduce the rate equation. In the slow step, there is only one halogenoalkane, hence the rate is first order with respect to halogenoalkane and zero order with respect to hydroxide. Therefore the rate equation will be: rate = k[RX] The overall order is one, hence we call this the SN1 mechanism. Tertiary halides will favour SN1 as more electron donating alkyl groups can stabilise the carbocation intermediate to a greater extent. Therefore the carbocation is more likely formed, and this in turn favours SN1 mechanism. SN2 Mechanism SN2 mechanism is a one step reaction. The OH- nucleophile will attack the carbon from directly behind the C-Cl bond. In this step the C-O bond is formed while the C-Cl bond is broken. Usually in schools we are required to draw the transition state, which emphasises that the OH, C and Cl groups are along the same axis. Since this is the only step in SN2, it must be the rate determining step. One halogenoalkane and one OH- are involved, hence the rate is first order with respect to both halogenoalkane and OH-. Therefore the rate equation will be: rate = k[RX][OH-] The overall order is two, hence we call this the SN2 mechanism. Primary halides will favour SN2 as there are less bulky alkyl groups. This means that the nucleophilic attack from directly behind the C-X bond will experience less steric hinderance. This makes the back door attack occur more readily and hence favours SN2 mechanism. For the detailed step-by-step discussion on how to draw both SN1 and SN2 mechanisms, check out this video! Topic: Halogenoalkane, Organic Chemistry, A Level Chemistry, Singapore Found this video useful? Please LIKE this video and SHARE it with your friends! SUBSCRIBE to my YouTube Channel for new A Level Chemistry video lessons every week at https://www.youtube.com/ChemistryGuru Any feedback, comments or questions to clarify? Suggestions for new video lessons? Drop them in the COMMENTS Section, I would love to hear from you! Need an experienced A Level Chemistry tutor to boost your grades? Check out the SEVEN reasons why Chemistry Guru can provide the best A Level Chemistry Tuition for you: WEBSITE: https://chemistryguru.com.sg/ -~-~~-~~~-~~-~- Please watch my latest video: "Valence Shell Electron Pair Repulsion (VSEPR) Theory and Shapes of Molecules" https://www.youtube.com/watch?v=q_NeyW5pe-Y -~-~~-~~~-~~-~-
sn2 reaction explained
 
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Details of sn2 mechanism with view of sterics, electronegativity, dipole inteactions, and rate determining step as well as alpha carbon reactivity
Views: 104 Alberto A.
Nucleophilic substitution: reaction of HBr with ethanol.
 
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This takes you through the stages in the nucleophilic substitution reaction between ethanol and hydrogen bromide. Referred to as an Sn2 mechanism, there are 2 particles involved in the rate-determining first step. There is an accompanying handout available at http://www.franklychemistry.co.uk/nucleophilic_substitution.html
Views: 14487 FranklyChemistry
Sn2 Stereochemistry
 
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Sn2 Stereochemistry
Views: 192933 Khan Academy
Free radical reactions | Substitution and elimination reactions | Organic chemistry | Khan Academy
 
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Free radical reactions. Created by Sal Khan. Watch the next lesson: https://www.khanacademy.org/science/organic-chemistry/substitution-elimination-reactions/sn1-sn2-sal/v/naming-alkyl-halides?utm_source=YT&utm_medium=Desc&utm_campaign=organicchemistry Organic Chemistry on Khan Academy: Carbon can form covalent bonds with itself and other elements to create a mind-boggling array of structures. In organic chemistry, we will learn about the reactions chemists use to synthesize crazy carbon based structures, as well as the analytical methods to characterize them. We will also think about how those reactions are occurring on a molecular level with reaction mechanisms. Simply put, organic chemistry is like building with molecular Legos. Let's make some beautiful organic molecules! About Khan Academy: Khan Academy offers practice exercises, instructional videos, and a personalized learning dashboard that empower learners to study at their own pace in and outside of the classroom. We tackle math, science, computer programming, history, art history, economics, and more. Our math missions guide learners from kindergarten to calculus using state-of-the-art, adaptive technology that identifies strengths and learning gaps. We've also partnered with institutions like NASA, The Museum of Modern Art, The California Academy of Sciences, and MIT to offer specialized content. For free. For everyone. Forever. #YouCanLearnAnything Subscribe to Khan Academy’s Organic Chemistry channel: https://www.youtube.com/channel/UCNKPjijOc0WEJ7DIV_Vay3g?sub_confirmation=1 Subscribe to Khan Academy: https://www.youtube.com/subscription_center?add_user=khanacademy
Views: 659667 Khan Academy
Nucleophilic Substitution Reaction : SN2 and SN1 | Organic chemistry
 
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Presence of partial positive charge on the carbon makes it susceptible to attack by nucleophiles. If nucleophile is stronger than the halide ion, the halogen atom gets displaced with its bonding electron pair and a new bond is formed between the carbon and nucleophile. These reactions are called nucleophilic substitution reactions(type of heterolytic reaction). Two types are there – (i) Bimolecular mechanism : One stage process. Two molecules simultaneously undergoing covalency change in the rate determining step. R.D.S step is the formation of the transition state. (ii) Unimolecular mechanism: Two stage process. 1st step – slow heterolysis of the compound to form carbocation. 2nd step – combination between carbocation & substituting nucleophilic reagent. Rate determining step is the first one. Since in this step only one molecule is undergoing a covalency change, this type of mechanism is called unimolecular.
Views: 114 Sarbajit Dey
Organic Chemistry - Reaction Mechanisms
 
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This organic chemistry video tutorial provides a basic introduction into reaction mechanisms. It explains the four fundamental reactions such as addition reactions, elimination reactions, substitution reactions, and rearrangements. Here is a list of topics: 1. Electrophilic Addition Reactions of Alkenes 2. Nucleophilic Addition Reactions of Ketones 3. Carbocation Rearrangements and Ring Expansion Examples 4. SN2 SN1 E1 and E2 Reaction Mechanisms 5. Nucleophilic Substitution Reactions 6. Elimination Reactions 7. E1CB Reaction 8. Free Radical Reactions - Radical Substitution Mechanism 9. Electrophilic Aromatic Substitution Reactions 10. Nucleophilic Aromatic Substitution Reactions 11. Addition Elimination Reaction Mechanism 12. Elimination Addition Reaction Mechanism Subscribe: https://www.youtube.com/channel/UCEWpbFLzoYGPfuWUMFPSaoA?sub_confirmation=1 Access to Premium Videos: https://www.patreon.com/MathScienceTutor https://www.facebook.com/MathScienceTutoring/ New Organic Chemistry Playlist https://www.youtube.com/watch?v=6unef5Hz6SU&index=1&list=PL0o_zxa4K1BXP7TUO7656wg0uF1xYnwgm&t=0s
Nucleophilic Substitution reaction (SN)
 
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A nucleophile is an the electron rich species that will react with an electron poor species A substitution implies that one group replaces another. Nucleophilic substitution reactions occur when an electron rich species, the nucleophile, reacts at an electrophilic saturated C atom attached to an electronegative group , the leaving group. SN1 Mechanism or Unimolecular Nucleophilic Substitution – S means Substitution , N means Nucleophilic & 1(one) for unimolecular. Unimolecular reactions are those reactions in which rate determining step is unimolecular. In an SN1 reaction, the rate determining step is the loss of the leaving group to form the intermediate carbocation. The more stable the carbocation is, the easier it is to form, and the faster the SN1 reaction will be. SN2 Mechanism or Bimolecular Nucleophilic Substitution – S means Substitution , N means Nucleophilic & 2 (two) for bimolecular. In SN2 mechanism , one molecule of alkyl halide & one molecule of aq. alkali combine together to form transition state .This is slow & rate determining step. So reaction is bimolecular. Related Article: Nucleophilic Substitution reaction (SN): https://chemistryonline.guru/substitution-reaction/ Like our Facebook page for updates and new tutorials at: https://www.facebook.com/chemistryonline.guru/ Our website: https://chemistryonline.guru
Electrophilic Substitution, Benzene Mechanism - Organic Chem
 
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In this video we want to discuss the electrophilic substitution mechanism of benzene using 2 reactions as example. Nitration of Benzene The first reaction is nitration of benzene to nitrobenzene. This reaction is done using concentrated nitric acid in concentrated sulphuric acid catalyst at 50 to 60 degree celsius. The first step involves the generation of electrophile NO2+ which is formed from the reaction between conc HNO3 and conc H2SO4. In the second step, which is the rate determining step or slow step, benzene will react with the electrophile NO2+. For arrow pushing we have to draw the full arrow, which represents the movement of 2 electrons, from benzene ring (electron rich region) to nitrogen in NO2+ (electron poor region). The intermediate formed is highly unstable as the benzene is positively charged and it loses the resonance stability due to the opening of delocalised ring. In the third step, the intermediate will deprotonate or remove a H+ to form product nitrobenzene. The H+ will combine with HSO4- intermediate to regenerate H2SO4 catalyst. Bromination of Benzene The second reaction is bromination of benzene to bromobenzene. This reaction is done via Br2 in FeBr3 catalyst. The mechanism is effectively the same, namely: Step 1 - generate electrophile Br+ from Br2 and FeBr3 Step 2 - carbon in benzene uses 2 electrons from delocalised pi system to form a bond with Br+, generating an unstable intermediate Step 3 - deprotonation of intermediate to form bromobenzene and regeneration of FeBr3 catalyst. For the detailed step-by-step discussion on how to draw the mechanism, check out this video! Topic: Benzene (Hydrocarbon), Organic Chemistry, A Level Chemistry, Singapore Found this video useful? Please LIKE this video and SHARE it with your friends! SUBSCRIBE to my YouTube Channel for new A Level Chemistry video lessons every week at https://www.youtube.com/ChemistryGuru Any feedback, comments or questions to clarify? Suggestions for new video lessons? Drop them in the COMMENTS Section, I would love to hear from you! Need an experienced A Level Chemistry tutor to boost your grades? Check out the SEVEN reasons why Chemistry Guru can provide the best A Level Chemistry Tuition for you: WEBSITE: https://chemistryguru.com.sg/ -~-~~-~~~-~~-~- Please watch my latest video: "Valence Shell Electron Pair Repulsion (VSEPR) Theory and Shapes of Molecules" https://www.youtube.com/watch?v=q_NeyW5pe-Y -~-~~-~~~-~~-~-
20.1 Mechanism for the  Nitration of Benzene [HL IB Chemistry]
 
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Conc. nitric and sulphuric acid plus a bit of benzene and you are on your way.
Views: 6569 Richard Thornley
SN1 Reaction
 
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Why is SN2 a one-step reaction and SN1 a two-step reaction! Argh! Just listen to Dave, he'll tell you about the mechanism, intermediate, and lack of stereospecificity for the SN1 reaction. Look out for racemic mixtures! Learn Organic Chemistry the easy way with Professor Dave! Subscribe: http://bit.ly/ProfDaveSubscribe [email protected] http://patreon.com/ProfessorDaveExplains http://facebook.com/ProfessorDaveExplains http://twitter.com/DaveExplains http://instagram.com/DaveExplains General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Organic Chemistry Tutorials: http://bit.ly/ProfDaveOrgChem Biochemistry Tutorials: http://bit.ly/ProfDaveBiochem Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 Modern Physics Tutorials: http://bit.ly/ProfDavePhysics2 Mathematics Tutorials: http://bit.ly/ProfDaveMaths Biology Tutorials: http://bit.ly/ProfDaveBio American History Tutorials: http://bit.ly/ProfDaveAmericanHistory
Views: 106845 Professor Dave Explains
Chemistry | Basic Start Of Sn1 & Sn2 I Er. Dushyant Kumar | NEET/JEE-2019
 
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In this video basics about the sn1 & sn2 are given with some examples 1 solvent 2 steps 3 rate 4 rearrangement #IIT #NEET #sn1&sn2 #helios #educore #helioseducore #nuclei #radioactivity #nuclear #alpha #emission #radiation #physics #nuturn #internal #reactions #energy #beta #dushyantkumar #dushyant #kumar #video #lectures #NEET #JEE #IIT #2019 #best #book #for #NEET #radioactivity decay #l,b Decay #sn1 #sn2 #basic #solvent #step #rate #rearrangement #examples Helios Educore Pvt. Ltd. Sunshine Business Park, Plot - 5A, Sector-94, Noida (UP) INDIA-201301 Chemistry Video Lectures to prepare for JEE-Main, JEE-Advanced, NEET and Board Exams. visit us : www.helioseducore.com Email : [email protected] Mob. : 08010000068 For Purchase : http://helioseducore.com/product-category/buy-book/ or Amazon Search Er Dushyant Kumar
Views: 29652 Helios Educore
34.03 Reaction Rates in Electrophilic Aromatic Substitution
 
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Changes in electron density in the first step of electrophilic aromatic substitution. (De)stabilizing effects of electron-donating and withdrawing groups on cationic sigma complexes.
Views: 406 Michael Evans
Practice Problem: Electrophilic Aromatic Substitution Rates
 
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We know about the products of these reactions, but how fast do they go? Give these a shot. Subscribe: http://bit.ly/ProfDaveSubscribe [email protected] http://patreon.com/ProfessorDaveExplains http://professordaveexplains.com http://facebook.com/ProfessorDaveExpl... http://twitter.com/DaveExplains General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Organic Chemistry Tutorials: http://bit.ly/ProfDaveOrgChem Biochemistry Tutorials: http://bit.ly/ProfDaveBiochem Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 Modern Physics Tutorials: http://bit.ly/ProfDavePhysics2 Mathematics Tutorials: http://bit.ly/ProfDaveMaths Biology Tutorials: http://bit.ly/ProfDaveBio American History Tutorials: http://bit.ly/ProfDaveAmericanHistory
sn1 and sn2 reaction mechanism in hindi
 
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Follow me on unacademy for upcoming courses- https://unacademy.com/user/krishnaaakash2 modern physics and wave video link- https://unacademy.com/lesson/course-overview-in-hindi/HI9ULWHQ aiims 2018 important question link- https://unacademy.com/course/aiims-and-jee-advance-physics-crash-course/0D0LUJDE neet 2018 solution link- https://unacademy.com/course/hindi-neet-2018-coderr-solution-chemistry-and-physics/3B055A7F general organic chemistry link- https://unacademy.com/course/hindi-general-organic-chemistry-839/9C1EV5QQ
Views: 176595 Aakash krishna
Nucleophilic Substitution | Sn1 Reaction | Sn2 Reaction | Substitution Reactions | Sn2 Mechanism
 
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Mechanisam is the two limiting mechanisms of nucleophilic aliphatic substitution at saturated carbon and the SN1-mechanisam is worked on the principle of rate law, an SN1 reaction is first order overall, and the concentration of the nucleophile does not affect the rate.a nd The implication is that the nucleophile does not participate in the rate limiting step or any prior steps.for example The C-Cl bond in the halogenoalkane starts to lengthen and weaken,then The chloride ion is eventually detached from the carbon atom and a flat carbocation forms.
Views: 210 Gtek
Chemistry-HOT'S Questions For Sn1 & SN2 | Part-2 | Er. Dushyant Kumar | NEET/JEE-2019
 
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Download PDF From: https://drive.google.com/open?id=1482s_PXdehIvoVUi7knCKlj667KAhXct ABOUT THE VIDEO-: Nucleophilic substitution , its mechanism in SN1 and SN2 and Rate of reactions are explained in the video,part-1. The explanation of the mechanism is given through the questions of High Order Thinking (HOT's) Level. Once you will solve these questions , the concept related to substitution reaction can be understand easily. These sixteen questions will clear your misconcepts. #IIT #NEET #sn1andsn2 #helios #educore #helioseducore #nuclei #radioactivity #nuclear #alpha #emission #radiation #physics #nuturn #internal #reactions #energy #beta #dushyantkumar #dushyant #kumar #video #lectures #NEET #JEE #IIT #best #book #for #NEET #sn1 #sn2 #basic #solvent #step #rate #rearrangement #examples #bromobenzene #SN1Reaction #SN1Reaction #Optical #incative #active #moleculerity #nucleophilic #unimolecular #bimolecular #Substitution #products #hydrolysis #alcohalic #potassium #hydroxide #heat #chlorine #NbromoSuccanamide #racemicMixture #acetone #hydrogeniodide #methanol Helios Educore Pvt. Ltd. Sunshine Business Park, Plot - 5A, Sector-94, Noida (UP) INDIA-201301 Chemistry Video Lectures to prepare for JEE-Main, JEE-Advanced, NEET and Board Exams. visit us : www.helioseducore.com Email : [email protected] Mob. : 08010000068 For Purchase : http://helioseducore.com/product-category/buy-book/ or Amazon Search Er Dushyant Kumar
Views: 15085 Helios Educore
Simply Mechanisms 5: SN1. Reaction of 2-bromo-2-methylpropane with aqueous KOH.
 
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Find an accompanying mindmap here: http://franklychemistry.co.uk/simply_mechanisms/9_Simply_Mechanisms5_Haloalkanes_SN1.pdf This looks at the mechanism of the reaction of 2-bromo-2-methylpropane with aqueous hydroxide ions. Known as SN1 for short, this stands for substitution nucleophilic first order. 2-bromo-2-methylpropane is a tertiary haloalkane. They undergo SN1 reactions with aqueous hydroxides, while primary haloalkanes undergo SN2 reactions. In SN1 only the haloalkane molecule is involved in the slow rate-determining step. It is known as a unimolecular reaction, where the 1 comes from in SN1. In the SN2 mechanism with primary haloalkanes the haloalkane molecule and hydoxides ion are both involved in the slow step. It is a bimolecular reaction. This is where the 2 comes from in SN2.
Views: 8545 FranklyChemistry
SUBSTITUTION NUCLEOPHILIC REACTION. WHAT IS SN1 AND SN2 REACTION?(BENGALI)
 
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The SN2 reaction is a type of reaction mechanism that is common in organic chemistry. In this mechanism, one bond is broken and one bond is formed synchronously, i.e., in one step. SN2 is a kind of nucleophilic substitution reaction mechanism. Since two reacting species are involved in the slow (rate-determining) step, this leads to the term substitution nucleophilic (bi-molecular) or SN2, the other major kind is SN1.[1] Many other more specialized mechanisms describe substitution reactions. The reaction type is so common that it has other names, e.g. "bimolecular nucleophilic substitution", or, among inorganic chemists, "associative substitution" or "interchange mechanism". The SN1 reaction is a substitution reaction in organic chemistry. "SN" stands for nucleophilic substitution and the "1" represents the fact that the rate-determining step is unimolecular.[1][2] Thus, the rate equation is often shown as having first-order dependence on electrophile and zero-order dependence on nucleophile. This relationship holds for situations where the amount of nucleophile is much greater than that of the carbocation intermediate. Instead, the rate equation may be more accurately described using steady-state kinetics. The reaction involves a carbocation intermediate and is commonly seen in reactions of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions, with secondary or tertiary alcohols. With primary and secondary alkyl halides, the alternative SN2 reaction occurs. In inorganic chemistry, the SN1 reaction is often known as the dissociative mechanism. This dissociation pathway is well-described by the cis effect. A reaction mechanism was first proposed by Christopher Ingold et al. in 1940.[3] This reaction does not depend much on the strength of the nucleophile unlike the SN2 mechanism. This type of mechanism involves two steps. The first step is the reversible ionization of Alkyl halide in the presence of aqueous acetone or an aqueous ethyl alcohol. This step provides a carbocation as an intermediate. In the second step this carbocation is attacked by the nucleophile to form the product.
Views: 179 SOUMIK'S BIOLOGY
Simply Mechanisms 2. Electrophilic Addition 2. Ethene & Bromine
 
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Find an accompanying mindmap here: http://franklychemistry.co.uk/simply_mechanisms/2_Simply_Mechanisms2_Ethene_Bromine.pdf One in a series of videos looking at organic chemistry mechanisms. This one looks at the electrophilic addition mechanism for ethene reacting with bromine It explains the mechanism in detail, with the help of simple animations and molecular models. The Br2 molecule is non-polar. The C=C double bond is made up of a sigma and pi bond. All 6 atoms in ethene lie on the same flat plane. The pair of electrons of the pi bond spend most of their time either above or below this plane. They are more exposed to incoming electrophiles and the pi bond is weaker than the sigma bond. As the bromine molecule passes the electron-rich double bond of the ethane molecule it becomes polarised. This is a 2-step mechanism. In the first step -slow step- rate-determining step - the pi bond breaks and the Br-Br bond breaks. The Br-Br bond breaks by way of heterolytic fission, meaning that both electrons of the bond go to one bromine. This creates a bromide ion and a Br+ electrophile. The pair of electrons of the pi bond are then used to form a bond with the Br+ electrophile. The other carbon of the C=C bond will have lost the electron it contributed to form the original pi bond. It will then have a positive charge, explaining why the intermediate, formed from the first step, is called a carbocation. In the fast step the bromide ion and carbocation then combine to form the product. Ethene has then reacted with bromine to produce the haloalkane called 1,2-dibromoethane.
Views: 4951 FranklyChemistry
Rate of SN1 Reaction is based on Carbocation Formation (The Train)
 
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The SN1 Reaction is a two-step nucleophilic substitution reaction: The first step or the slow rate-determining step is when the leaving group detaches-- "the train." Once "the train" leaves, the nucleophile attacks the carbocation. Rate=k[RX].
Views: 275 Alan Habibi
EAS Mechanism and Sigma Complex Resonance by Leah4sci
 
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http://leah4sci.com/EAS Presents: Electrophilic Aromatic Substitution Reaction Mechanism and Resonance for the Sigma Complex Intermediate Struggling with Orgo? Grab my free ebook '10 Secrets To Acing Organic Chemistry' here: http://leah4sci.com/orgo-ebook/ This video may very well be the MOST IMPORTANT one in my EAS series. This video takes you through the step by step mechanism of benzene reaching out for a super-electrophile and reforming its aromaticity. I also show you how to draw the resonance intermediates for the positively charged sigma complex. Catch the entire EAS series on my website: http://leah4sci.com/electrophilic-aromatic-substitution-mechanisms-and-reactions/ For more in-depth review including practice problems and explanations, check out my online membership site: http://leah4sci.com/join For private online tutoring visit my website: http://leah4sci.com/organic-chemistry-tutor/ Finally, for questions and comments, find me on social media here: Facebook: https://www.facebook.com/Leah4sci Twitter: https://twitter.com/Leah4Sci Google+ https://plus.google.com/u/0/+LeahFisch Pinterest: http://www.pinterest.com/leah4sci/
Views: 44019 Leah4sci
Chemistry - Nucleophilic Substitution
 
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Chemical Mechanisms - Nucleophilic Substitution. I hope this video makes sense because I find mechanisms one of the hardest things in chemistry. Please comment, rate and subscribe :)
Views: 176 KnowYourScience
Types of Reactions Part-1 I NEET/JEE
 
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Helios Educore Pvt. Ltd. Sunshine Business Park, Plot - 5A, Sector-94, Noida (UP) INDIA-201301 Chemistry Video Lectures to prepare for JEE-Main, JEE-Advanced, NEET & and Board Exams. visit us : www.helioseducore.com Email : [email protected] Mob. : 08010000068 For Purchase : http://helioseducore.com/product-category/buy-book/ or Amazon Search Er Dushyant Kumar
Views: 717410 Helios Educore
E1 Reaction
 
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Here we examine the mechanism for the E1 reaction. Don't worry, it's just these four for now! Learn Organic Chemistry the easy way with Professor Dave! Subscribe: http://bit.ly/ProfDaveSubscribe [email protected] http://patreon.com/ProfessorDaveExplains http://facebook.com/ProfessorDaveExplains http://twitter.com/DaveExplains http://instagram.com/DaveExplains General Chemistry Tutorials: http://bit.ly/ProfDaveGenChem Organic Chemistry Tutorials: http://bit.ly/ProfDaveOrgChem Biochemistry Tutorials: http://bit.ly/ProfDaveBiochem Classical Physics Tutorials: http://bit.ly/ProfDavePhysics1 Modern Physics Tutorials: http://bit.ly/ProfDavePhysics2 Mathematics Tutorials: http://bit.ly/ProfDaveMaths Biology Tutorials: http://bit.ly/ProfDaveBio American History Tutorials: http://bit.ly/ProfDaveAmericanHistory
Alkene + NBS Reaction Mechanism - Free Radical Bromination - Halogenation
 
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This organic chemistry tutorial video discusses the free radical bromination reaction between an alkene and NBS. It provides the reaction mechanism for NBS as well. NBS is known as N-bromosuccinimide. It's a radical halogenation reaction that produces monobrominated allylic bromides. The example for this reaction includes NBS with cyclohexene to form 1 product, 3-methylcyclopentene to form 4 products and 2-methyl-2-butene to form up to 6 products including R & S stereoisomers and E / Z cis trans geometric diastereomers. Other topics include stability of the radical intermediate by resonance stabilization. Other radical halogenation reactions were compared such as Br2 with heat or light - however, a high concentration of Br2 can lead to the addition product of vicinal dibromides. In addition, the allylic halogenated product of Br2 and Light produces H-Br which can react with the double bond of the halogenated product producing vicinal dibromides. NBS avoids all of these side reactions by consuming any additional H-Br produced as well as generating a low concentration of Bromine which favors the yield of a radical halogenated product. This video contains plenty of examples and practice problems of free radical substitution reactions.
Sn1 reactions intro
 
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Views: 92203 Khan Academy
9. Pentavalent Carbon? E2, SN1, E1
 
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Freshman Organic Chemistry II (CHEM 125B) Preliminary X-ray analysis of molecules that have been designed to favor a carbon with five bonds seemed to suggest the possibility of a pentavalent intermediate in SN2 reactions, but further analysis of these structures showed just the opposite. Boron, however, can be pentavalent in such an environment. E2, SN1 and E1 mechanisms compete with the SN2 reaction. Factors controlling E2 eliminations are illuminated by kinetic isotope effects, stereochemistry, and regiochemistry. The competition between E2 and SN2 mechanisms influence the design of synthetic schemes, including those in which carbon nucleophiles play an important role. SN1 and E1 reactions involve carbocation intermediates and thus the possibility that the carbon skeleton will rearrange. 00:00 - Chapter 1. Using X-Ray to Investigate the Possibility of a Pentavalent Carbon Intermediate 14:41 - Chapter 2. The E2 Reaction and Kinetic Isotope Effects 19:51 - Chapter 3. Stereochemistry & Regiochemistry of E2 Elimination 32:20 - Chapter 4. Strategies for Substitution in Organic Synthesis 41:39 - Chapter 5. SN1 and E1 Reactions - Kinetic Evidence for SN1 Substitution 45:09 - Chapter 6. Carbocation Intermediates: Competition and Rearrangement Complete course materials are available at the Open Yale Courses website: http://oyc.yale.edu This course was recorded in Spring 2011.
Views: 3054 YaleCourses
Nucleophilic Substitution Reactions Explained
 
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Professor Davis provides a short introduction to the SN1 and SN2 nucleophilic substitution reaction mechanisms,
Views: 96236 ChemSurvival
Choosing Between SN1 and SN2 Reactions - Practice Problems (part 1)
 
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In this video, we will discuss the process for determining whether the reaction goes via an SN1 or SN2 mechanism. The complete video solution to these problems can be found at: https://www.chemistrysteps.com/when-is-the-mechanism-sn1-or-sn2/ For more topics and practice problems of Organic Chemistry visit: https://www.chemistrysteps.com/ If you are struggling with the overwhelming amount of material covered in Organic I and II, check this pack of powerful Study Guides to help you focus, save time and get a better grade! https://www.chemistrysteps.com/organic-chemistry-study-guide-cheat-sheets/
Views: 54 Chemistry Steps