ẞ-Eliminations that follow an E2 mechanism have stereochemical implications that need to beaddressed. Elimination MUST occur from a conformation with an "anti periplanar" between theleaving group and ẞ-hydrogen. This corresponds to a staggered conformation in acyclic systems and"trans-diaxial" in cyclohexane chairs.A. Examples of acyclic systemsHCH3EtNaOCH3H3C7EtBrCHOOSBrH CH3PhNaOH13H t-BuHHBrNaOHPhPh H1HOOGM

1. E2 Elimination and Stereochemistry: For an E2 elimination to occur, the leaving group and the…

Answered: ẞ-Eliminations that follow an E2…

Organic Chemistry

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Chapter16: Chemistry Of Benzene: Electrophilic Aromatic Substitution

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Problem 25VC: The following molecular model of a dimethyl-substituted biphenyl represents the lowest-energy...

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2) Draw Newman projections of all staggered conformations of (S)-butan-2-ol. Clearly mark the highest energy conformation. 3) Draw both chair conformations of (1S,3R)-1-chloro-3-isopropylcyclohexane. Clearly mark the most stable conformation, and also the conformation which enables E2 elimination.
Draw the structures for (Z)-3-methylhex-3-ene and the two major organic products for its reaction with HBr. Be sure to show all stereoisomers using wedge and dash stereochemistry at any chirality center.
Alcohols can be converted to alkyl chlorides using SOCl2 with complete inversion of stereochemistry. Using curved arrows draw the stepwise mechanism chlorination of an alcohol. be sure to include loan pairs necessary to the mechanism steps in any non-zero formal charges.
2. Our knowledge of chair conformations allows us to use them to determine a great deal about a reaction's mechanism. In particular, using a t-butyl group to 'fix' a cyclohexane in a single conformation can help us learn about the spatial requirements and energetics of a reaction. Consider the following two reaction products: a. NO NID ALOH 1) NaCN 2) H+ 1) NaBH4 2) H3O+ OH Group -H -CN -OH A Value (kcal/mol) Defined as 0 0.2 kcal/mol 1.0 kcal/mol Draw the most stable chair conformation for each of the two products. b. Based on the A values in the table above, do the two products have the most stable conformation at the new stereocenter?
6. Draw the stable conformations of the following molecules. A) (2R,3S)-3-methyl-2-hexanol (staggered Newman Projection). B) meso 1,2-dibromo cyclohexane in (chair conformation) 7. What is the value of the equilibrium constant for the following equilibrium? HC ECH + NaOH HC=C: Na + H₂O pk₂= 25 pka = 15.7
Stereochemistry The alkyl bromide below can undergo an E2 but not in its shown conformation. Draw the conformer (as a line drawing, not a Newman projection) out of which an E2 elimination can occur, with all bonds/groups in the original drawing included. 'Bu = tert-butyl H3C H H3C Br tBu alkyl bromide (b) Draw the alkene formed in the E2 elimination reaction of this alkyl bromide promoted by potassium tert-butoxide (KOtBu). (c) Indicate if this E2 elimination reaction is stereospecific or stereoselective (write or circle stereospecific or stereoselective) Regioselectivity (d) Two potential products can form in the following E2 elimination promoted by KOtBu. Circle the major alkene product. (e) KOtBu H3C H3C Indicate if the reaction in (d) is under kinetic control or thermodynamic control. (write or circle kinetic or thermodynamic control) 5
Compounds X and Y are both C5H11CI products formed in the radical chlorination of pentane. Base-promoted E2 elimination of X and Y gives, in each case, a single C5H10 alkene (ignoring double bond stereochemistry). Both X and Y react in SN2 fashion with sodium iodide in acetone; Y reacts faster than X. What is the structure of Y? • Do not use stereobonds in your answer. • In cases where there is more than one possible structure for each molecule, just give one for each. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. • Separate structures with + signs from the drop-down menu. ChemDoodle (Previous Next
Which of these products is the result of a hydride shift occuring during the substitution reaction of aqueous 2-chloro-3-methylpentane? CH3CH2CCH2CH3 || CH2 CH3CH(OH)CH(CH3)CH2CH3 CH2=CHC(CH3)=CHCH3 CH3CH=C(CH3)CH2CH3 CH3CH2C(CH3)CH2CH3 | OH
A difficult problem in the synthesis of PGF2α is the introduction of the OH group at C15 in the desired configuration. a. Label this stereogenic center as R or S. b. A well known synthesis of PGF2α involves reaction of A with Zn(BH4)2, a metal hydride reagent similar in reactivity to NaBH4, to form two isomeric products, B and C. Draw their structures and indicate their stereochemical relationship. c. Suggest a reagent to convert A to the single stereoisomer X.
Consider the reaction of 1,2-epoxy-1-methylcyclopentane below. It can be reacted with NaOCH3 to form product 1 or with CH3OH/H* to form product 2. 1 OCH3 a OH NaOCH3 CH₂OH CH3 give OCH 3 CH3 OH b J...CH3 OH с CH3OH CH3OH₂* CH3 OCH 3 OH d 2 OCH 3 CH3 Based on the stereochemistry shown here, product 1 would be structure [Select] and product 2 would be structure [Select]
Compound A, C₂H16 reacts with 1 molar equivalent(s) of hydrogen on catalytic hydrogenation. A undergoes reaction with ozone, followed by Zn treatment, to give: O CH3 O || CH3CCH₂CCH₂CCH3 CH3 Compound A Propose a structure for A. • You do not have to consider stereochemistry. • You do not have to explicitly draw H atoms. • In cases where there is more than one answer, just draw one.
11. Trans-1-bromo-2-methylcyclohexane will yield a non-Zaitsev elimination product (3- methylcyclohexene) upon reaction with KOH. Show this reaction by drawing the chair conformations of the reactant and product. Include the curved arrows and explain why the product is not a non-Zaitsev product. (

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