Alkynes can be made by dehydrohalogenation of vinylic halides in a reaction that is essentially...
Question:
Alkynes can be made by dehydrohalogenation of vinylic halides in a reaction that is essentially an E2 process. In studying the stereochemistry of this elimination, it was found that (Z)-2-chloro-2-butenedioic acid reacts 50 times as fast as the corresponding E isomer.
What conclusion can you draw about the stereochemistry of eliminations in vinylic halides? How does this result compare with eliminations of alkyl halides?
Dehydrohalogenation Reaction:
When hydrogen and a halogen are eliminated from the reactant, such elimination reactions are known as dehydrohalogenation reactions. Alkenes are usually prepared using this method. One such example is the synthesis of ethylene by reacting ethyl chloride with {eq}{\rm KOH} {/eq}
Answer and Explanation: 1
Become a Study.com member to unlock this answer! Create your account
View this answerIf the rotation around the double bonds is limited, then the E-Z isomerism occurs. Z isomers have the groups having the same priority on the same...
See full answer below.
Ask a question
Our experts can answer your tough homework and study questions.
Ask a question Ask a questionSearch Answers
Learn more about this topic:
Get access to this video and our entire Q&A library
E2 Elimination & Mechanism Reaction: Definition & Examples
from
Chapter 7 / Lesson 6
24K
Learn about E2 reaction. Understand E2 reaction, its mechanism, and stereochemistry of E2 reactions on secondary and tertiary alkyl halide, and review examples.
Related to this Question
- Like alkenes, conjugated dienes can be prepared by elimination reactions. Draw a stepwise mechanism for the acid-catalyzed dehydration of 3-methylbut-2-en-1-ol ((CH_3)_2C=CHCH_2OH) to isoprene (CH_2=C(CH_3)CH=CH_2).
- The reaction of 1-butene with HBr in the absence of peroxides yields 2-bromobutane. The mechanism for the reaction involves: A. Isomerization of the 2-bromobutane produced initially B. Attack on the alkene by a bromine atom C. Attack on the alkene by a
- Reaction of cis-2-butene with m-chloroperoxybenzoic acid yields an epoxide different from that obtained by reaction of the trans isomer. Explain.
- In the Wittig reaction, a phosphorus ylide ad[{Image src='img181392161555440383093.jpg' alt='' caption=''}]ds to a ketone or an aldehyde to yield an alkene. Write a complete stepwise mechanism for the
- 1,2-Diols are converted to carbonyl compounds when treated with strong acids, in a reaction called the pinacol rearrangement. (a) Draw a stepwise mechanism for this reaction. (Hint: The reaction proceeds by way of carbocation intermediates.) (b) Assuming
- Draw the structures of the organoboranes formed when borane reacts with alkene below, including the regiochemistry and stereochemistry as appropriate. Propose a mechanism for the given reaction.
- Draw the structures of the organoboranes formed when borane reacts with alkene below, including the regiochemistry and stereochemistry as appropriate. Propose a mechanism for the given reaction below.
- Draw the structures of the organoboranes formed when borane reacts with alkene below, including the regiochemistry and stereochemistry as appropriate. Propose a mechanism for the following reaction.
- Acid-catalyzed dehydration of 2. 2- dimethylcyclohexanol yields, in part. 1, 2-dimethylcyclohexene. Draw structural formulas for the two carbocation intermediates in this reaction.
- Write an equation for the reaction (ignoring stereochemistry) involving the bromination of a sample of trans-cinnamic acid (3-phenylpropenoic acid) to form 2,3-dibromo-3-phenylpropanoic acid.
- The enolate derived from diethyl malonate reacts with a variety of electrophiles (not just alkyl halides) to form new carbon-carbon bonds. With this in mind, draw the products formed when Na+-CH(CO2Et)2 reacts with the given electrophile, followed by trea
- What is the mechanism of an aldehyde reacting with Fehling's solution and Tollen's reagent? I know it is oxidized to a carboxylic acid, but I want to know the mechanism.
- Identify the mechanism by which the following reaction proceeds. Is it Electrophilic addition, E2 Elimination, SN1 Nucleophilic substitution, SN2 Nucleophilic substitution, Carbonyl nucleophilic addition, Nucleophilic subs at Carbonyl (acyl Xfer), or Conj
- Identify the mechanism of the following reaction. Is it Electrophilic addition, E2 Elimination, SN1 Nucleophilic substitution, SN2 Nucleophilic substitution, Carbonyl nucleophilic addition, Nucleophilic subs at Carbonyl (acyl Xfer), or Conjugate (nucleoph
- The enolate derived from diethyl malonate reacts with a variety of electrophiles (not just alkyl halides) to form new carbon-carbon bonds. With this in mind, draw the products formed when Na+-CH(CO2Et)2 reacts with the shown electrophile, followed by trea
- Aldehydes can be prepared by the Wittig reaction using (methoxymethylene) triphenylphosphorane as the Wittig reagent and then hydrolyzing the product with acid. (a) How would you prepare the necessary phosphorane? (b) Propose a mechanism for
- In a nucleophilic substitution reaction, complete inversion of configuration at the reactive carbon atom is observed. Would the mechanism most likely be S_N1 or S_N2? Briefly explain the reasoning behind your answer.
- Identify the halide(s) that react in a SN1 reaction. Check all that apply. a.1-bromo-2-butene b. 2-bromo-2-phenylpropane c.bromobenzene d.1-bromo-1-butene e.benzyl bromide
- Terminal alkynes react with Br_2 and water to yield bromo ketones. Propose a mechanism for the reaction. To what reaction of alkenes is the process analogous?
- When 3-methyl-1-butene reacts with HBr, two alkyl halides are formed, 2-bromo-3-methyl butane and 2-bromo-2-methyl butane. Give a mechanism that explains the formation of these products.
- Identify the mechanism by which the given reaction proceeds. Is it Electrophilic addition, E2 Elimination, SN1 Nucleophilic substitution, SN2 Nucleophilic substitution, Carbonyl nucleophilic addition, Nucleophilic subs at Carbonyl (acyl Xfer), or Conjugat
- 1. a) Write mechanisms showing why bromination of trans-cinnamic acid yields the product you obtained as a racemic mixture of enantiomers. 1b). Draw a stereochemical projection for each enantiomer and
- Identify the mechanism by which the given transformation reaction proceeds. Is it Electrophilic addition, E2 Elimination, SN1 Nucleophilic substitution, SN2 Nucleophilic substitution, Carbonyl nucleophilic addition, Nucleophilic subs at Carbonyl (acyl Xfe
- Tery-butyl alcohol reacts with hydrobromic acid via the _____ mechanism to produce tert-butyl bromide a. E1 b. E2 c. S-(N)1 d. S_(N)2
- Identify the mechanism of the below-mentioned reaction. Is it Electrophilic addition, E2 Elimination, SN1 Nucleophilic substitution, SN2 Nucleophilic substitution, Carbonyl nucleophilic addition, Nucleophilic subs at Carbonyl (acyl Xfer), or Conjugate (nu
- One of the by-products of a reaction is 2-methyl-2-butene. A) Suggest a mechanistic pathway for the formation of this alkene. B) How is this by-product removed during the purification?
- Although anti periplanar geometry is preferred for E2 reactions, it isn't absolutely necessary. The deuterated bromo compound shown here reacts with a strong base to yield an undeuterated alkene. Clearly, a syn elimination has occurred. Make a molecular m
- Photolysis of the cis-cyclobutene isomer yields cis-cyclododecaen-7-yne, but photolysis of the trans isomer yields trans-cyclododecaen-7-yne. Explain these results, and identify the type and stereochemistry of the pericyclic reaction.
- Give the structure of the organic product expected when I_2CH_2 reacts with the following alkene in the presence of a Zn-Cu couple: Ignore stereochemistry.
- Upon reaction of 2-ethyl-3-phenylcyclohexanol with concentrated aqueous hydrochloric acid, a minor product of 3-ethyl-2-phenyl-1-cyclohexene was found. Show the mechanism for this reaction.
- Given that acetophenone is a meta-director, draw all three resonance structures for the carbocation intermediate that results from Step 2 in the electrophilic aromatic substitution reaction when acetophenone reacts with Br2 in the presence of FeBr3. Assig
- S_N 1 reactions produce a racemic mixture because the mechanism involves a ____. A. carbocation. B. carbanion. C. unreactive. D. low energy.
- 1-hexanol was prepared by reacting an alkene with either hydroboration-oxidation or oxymercuration-reduction. Draw the structure of the alkene that was used to prepare the alcohol in highest yield. You do not have to consider stereochemistry. You do no
- Trans alkenes are converted into their cis isomers and vice versa on epoxidation followed by treatment of the epoxide with triphenylphosphine. Propose a mechanism for the epoxide \to alkene reaction.
- In light of the fact that tertiary alkyl halides undergo spontaneous dissociation to yield a carbocation plus halide ion, propose a mechanism for the following reaction.
- What is the expected major product in the reaction? Be sure to include stereochemistry to determine your answer. 3,5-dimethyl-1-cyclopentene (racemic) (D_2SO_4) right-arrow (DOCH_3; Et_2O)
- Write the reaction scheme to provide the following compounds from benzene. P-Bromonitrobenzene m-Bromoethylbenzene Provide the reaction mechanism of the following reaction: Formation of acid anhyd
- The Wittig reaction is used for this experiment. In this experiment, cinnamaldehyde is used as the carbonyl compound and yields mainly the trans, trans-1,4-diphenyl-1,3-buatdiene, which is obtained as a solid. The cis, trans isomer is formed in smaller am
- Assuming that halogens add to alkyne in the same manner as they add to an alkene, propose a mechanism for and predict the product of the following reaction below.
- Assuming that strong acid adds to alkyne in the same manner as they add to an alkene, propose a mechanism for the given reaction.
- Reaction of an alkene with Br2 produces the dibromo compound. Generate complete and balanced reactions. What sort of addition reaction gives a monoborminated alkane, when reacting with an alkene?
- Use your general knowledge of alkene chemistry to suggest a mechanism for the following reaction.
- When pentanal reacts with ethylamine under conditions of acid catalysis, the major organic product is: a. a ketone b. a nitrile c. an imine d. an oxime e. a hydrazone
- A tautomerization reaction can occur with an imine in a way analogous to that of a ketone or aldehyde. Draw the tautomerization product enamine of the compound.
- An alkyne undergoes hydrogenation to produce an alkene as follows: RC(triple bond)CR + H_2 (Pd catalyst) alkene predict the product.
- Indole reacts with electrophiles at C3 rather than at C2. Draw resonance forms of the intermediate cations resulting from reaction at C2 and C3, and explain the observed results.
- Carbonyl Reactions at the a-Carbon: Complete the following mechanism involving 1-cyclohexylethan-1-one
- In the Ritter reaction, an alkene reacts with a nitrile in the presence of strong aqueous sulfuric acid to yield an amide. Propose a mechanism.
- Draw a mechanism that accounts for the formation of all stereoisomers isolated from this reaction: trans-3-phenyl-2-propenoic (trans-cinnamic acid) + Br2+ CH2Cl2 --> 2,3-dibromo-3-phenylpropanoic acid
- Isoborneol is converted into camphene on treatment with dilute sulfuric acid. Propose a mechanism for the reaction, which involves a carbocation rearrangement.
- Assuming that halogens add to alkyne in the same manner as an they add to alkene, propose a mechanism for and predict the product of the given reaction.
- Upon reaction of 2-ethyl-3-phenyl-1-cyclohexanolanol with concentrated aqueous hydrochloric acid, a minor product of 3-ethyl-2-phenyl-1- cyclohexene was found. Show the mechanism for this reaction.
- Consider the reaction of 1-methylcyclopentene with Cl2 and H2O 1) this reaction is an example of: a) Electrophilic subsitution, b) electrophilic addition c) elimination d) carbocation rearrangemen
- If you did an SN2 reaction with R-2-bromobutane, what would the stereochemistry of the product be? a) R b) S c) achiral d) racemic mixture e) NA
- When a cyclohexene reacts with chlorine in water the trans-2-chlorocyclohexanol is formed. Write the complete stepwise mechanism for this reaction. Be sure to show all intermediate structures and all
- If 5-hydroxypentanoic acid (HOCH_2CH_2CH_2CO_2H) is treated with an acid catalyst, an intramolecular esterification reaction occurs. What is the structure of the product?
- Given that an E2 reaction proceeds with anti-periplanar stereochemistry, draw the products of each elimination. The alkyl halides in (a) and (b) are diastereomers of each other. How are the products of these two reactions related? C6H5- is a phenyl g
- 1. Recalling that nucleophilic substitution reactions only occur at sp3 hybridized carbon atoms containing a leaving group, are there any molecules from table 1 that you suspect will not undergo nucle
- Alkenes react with HBr. For example, when CH2=CHCH2CH3 reacts with HBr, the product is 2-bromobutane. Q: Is the product chiral? Will a solution of the product be optically active or racemic? Will the
- The aldol reaction is catalyzed by acids as well as bases. What is the reactive nucleophile in the acid-catalyzed aldol reaction? Propose a mechanism.
- In a Diels-alder reaction, a dienophile would like to have a(n): A) electron-withdrawing group. B) electron-donating group. C) metal. D) any organic substituent.
- Alkyl halides react with hydrosulfide ion (HS^-) to give a product whose stereochemistry is inverted from that of the reactant. Draw the reaction of (S)-2-bromobutane with HS^- ion to yield 2-butanethiol, CH_3CH_2CH(SH)CH_3. Is the
- Reaction of HCl with 2-methylpropene yields 2-chloro-2-methylpropane. What is the structure of the carbocation formed during the reaction? Show the mechanism of the reaction.
- Write the mechanism of nucleophilic substitution of the given reaction including stereochemistry.
- Alkyl Halides: Elimination reaction with 2-bromobutane Draw the major product obtained when the following alkyl halide undergoes an E1 reaction. I
- Like carbocations, radicals formed from compounds that contain another functional group can undergo intramolecular reactions. Draw a stepwise mechanism for the chainpropagating steps of this intramolecular reaction.
- Assuming that halogens add to alkyne in the same manner as they add to alkenes, propose a mechanism for and predict the product of the following reaction.
- Acid chlorides undergo reaction with Grignard reagents at -78 C to yield ketones. Propose a mechanism for the reaction.
- When an \alpha -hydroxy amide is treated with Br_2 in aqueous NaOH under Hofmann rearrangement conditions, loss of CO_2 occurs and a chainshortened aldehyde is formed. Propose a mechanism.
- Drawing on what you know about the stereochemistry of alkene addition reactions, write the mechanism for the reaction of 2-butyne with one equivalent of Br_2.
- Reaction of acetone with D_3O^+ yields hexadeuterioacetone. That is, all the hydrogens in acetone are exchanged for deuterium. Review the mechanism of mercuric-ion-catalyzed alkyne hydration, and then propose a mechanism for this deuterium incorporation.
- 1. One of the following could easily form an alkene by E1 mechanism. Which is it, and what reactant would lead to the product? Show the product. 2. One of the compounds in #1 could form an alkene by E
- The given electrophilic addition reaction below involves a carbocation rearrangement. Predict the product and draw the complete arrow-pushing mechanism.
- The following electrophilic addition reaction involves a carbocation rearrangement. Predict the product and draw the complete arrow-pushing mechanism.
- The following electrophilic addition reaction below involves a carbocation rearrangement. Predict the product and draw the complete arrow-pushing mechanism.
- Methylenecyclohexane, on treatment with strong acid, isomerizes to yield 1-methylcyclohexene. Propose a mechanism by which the reaction might occur.
- Classify the given reaction as (1) an addition reaction, (2) a nucleophilic substitution reaction, (3) an electrophilic substitution reaction, or (4) a condensation reaction, the reaction of terephthalic acid with 1,2-ethanediol
- How would you prepare the following compounds from benzene, using a diazonium replacement reaction in your scheme? (a) p-Bromobenzoic acid (b) m-Bromobenzoic acid (c) m-Bromochlorobenzene (d) p-Methylbenzoic acid (e) 1,2,4-Tribromobenzene
- Write reactions for the synthesis of: a) 1,3-butadiene from 2-chlorobutane b) any conjugated diene from an alkene
- Assuming that strong acids add to alkynes in the same manner as they add to alkenes, propose a mechanism for the following reaction below.
- The Fischer esterification is really an example of: a. a nucleophilic acyl substitution reaction b. an aldol condensation reaction c. an elimination reaction (either E1 or E2) d. an electrophilic addition reaction e. a conjugated addition reaction
- Consider the reaction of the conjugated diene 1, 3-butadiene with one equivalent of HBr. Give the mechanism of this reaction, showing both resonance structures of the allylic carbocation intermediate and the formation of the 1, 2 and 1, 4 products.
- Identify the carboxylic acid chloride that might be used in a Friedel-Crafts acylation reaction to prepare each of the following acylbenzenes: (a) (b)
- The acetamido group (-NHCOCH3) is an ortho-para directing group in electrophilic aromatic substitution reactions. In the bromination of acetanilide, only para-substitution is observed. Draw the chemic
- Keeping in mind the mechanism for the dissolving metal reduction of alkynes to trans alkenes, write a stepwise mechanism for the following reaction, which involves the conversion of an \alpha
- Alkyl Halides: Substitution reaction with (2R, 3R)-2-chloro-3-methylpentane with CH3O- Draw the product formed when the structure below undergoes a substitution with NaOCH_3.
- Knoevenagel condensation is a reaction involving an active methylene compound (a CH_2 flanked by two electron-withdrawing groups) and an aldehyde and ketone. Propose a mechanism for the reaction below.
- Write a mechanism for the E1 elimination reaction of 2-methyl-cyclohexanol with phosphoric acid. Be as complete as possible and show electron flow for all steps. You should clearly indicate the mechan
- Can diborane (B 2 H 6 ) reacts with an alkene in a Hydroboration reaction or its BH 3 the one that reacts so the splitting of diborane to borane has to be considered?
- a. What is an SN1 reaction? Explain the mechanism for this reaction. b. What types of halides will undergo SN1 mechanisms and what type will not? Why? c. What other experimental conditions promote SN1 mechanism?
- Reaction of (S)-3-methyl-2-pentanone with methylmagnesium bromide followed by acidification yields 2,3-dimethyl-2-pentanol. What is the stereochemistry of the product? Is the product optically active?
- Which alkene reaction follows anti-Markovnikov addition mode? a) Acid-catalyzed hydration reaction. b) Hydroboration-oxidation reaction. c) Hydrohalogenation reaction. d) Halogenation reactions.
- Give the structure of the alkene formed in the following reaction.
- Predict the major alkene product from the given elimination:
- HBr addition to 1-hexene yields both 1-bromohexane and 2-bromohexane. Show the complete reaction mechanisms for both, showing nucleophiles and electrophiles with the bonds.
- The alkoxymercuration of alkenes involves the formation of an organomercury intermediate (I), which is reduced with NaBH4 to give an ether product. For the following reaction, predict the ether product and provide the mechanism formation.
Explore our homework questions and answers library
Browse
by subject