4. A double bond in a six-membered ring is usually more stable in an endocyclic position than in an exocyclic position. Hydrogenation data on two pairs of compounds follow. One pair suggests that the energy difference between endocyclic and exocyclic double bonds is about 9 kJ/mol. The other pair suggests an energy difference of about 5 kJ/mol. Which number do you trust as being more representative of the actual energy difference? Explain your answer. endocyclic exоcyclic 107 116 105 110 heats of hydrogenation (kJ/mol)

4. A double bond in a six-membered ring is usually more stable in an endocyclic position than in an exocyclic position. Hydrogenation data on two pairs of compounds follow. One pair suggests that the energy difference between endocyclic and exocyclic double bonds is about 9 kJ/mol. The other pair suggests an energy difference of about 5 kJ/mol. Which number do you trust as being more representative of the actual energy difference? Explain your answer. endocyclic exоcyclic 107 116 105 110 heats of hydrogenation (kJ/mol)

Organic Chemistry: A Guided Inquiry

2nd Edition

ISBN:9780618974122

Author:Andrei Straumanis

Publisher:Andrei Straumanis

Chapter18: Aromaticity

Section: Chapter Questions

Problem 3CTQ

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Compounds 1 and 2 were prepared, and the difference in their heats of combustion was found to be 17.2 kJ/mol (J. Am. Chem. Soc. 1961, 83, 606-614): H H 1 Shown below are the lowest-energy conformations of compounds 1 and 2. Identify which drawing matches which compound, and identify which compound has the larger heat of combustion. H H H H |||I 2 H 4 H H The first drawing is compound 1, and compound 1 has a larger heat of combustion because it is the less stable compound. O The first drawing is compound 2, and compound 2 has a larger heat of combustion because it is the less stable compound. The first drawing is compound 2, and compound 2 has a larger heat of combustion because it is the more stable compound. The first drawing is compound 1, and compound 1 has a larger heat of combustion because it is the more stable compound.
Addition of HCl to alkene X forms two alkyl halides Y and Z. Explain why addition of HCl occurs at the indicated C=C (called anexocyclic double bond), rather than the other C=C (called anendocyclic double bond).
Rank the following compounds from least to most stable. Least stable Most stable
For each reaction, decide whether substitution or elimination (or both) is possible, andpredict the products you expect. Label the major products. chlorocyclohexane + NaOCH3 in CH3OH
The AH° values of each compound is given below as kJ/mol. Calculate the entaphy change (AH) value of the following reacti on? 2CaOg) + 2SO2 (g + Ozg) →2 CasO41) -635.5 -296.9 0.0 -1432.7 (kJ/mol) A) 500.3 kJ B) -500.3 kJ С) -1000.6 kJ D) 2365.1 kJ E) -1094.1 kJ
Order the following in increasing priority A. -C, -CH, -OL B. -CH3, -CH2OH, -CH2CH3 C. -C≡CH, -CH゠CH2, -CH゠O
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?
TReview TOpics] [References Draw a structural formula for the major product of the reaction shown. CH3 CH3CHCH=CH2 Show product steréochemistry IF the reactant alkene has both carbons of the double bond within a • Do not show stereochemistry in other cases. If the reaction produces a racemic mixture, just draw one stereoisomer. C P opy aste C.
to this answer, estion 54 A cycloalkene having only one cartion.carbon double bond will have the general formula CnH2n-4 CnH2n 2 CnH2n CnH2h+2 AMoving to the dext questioni prevents chaniges to this answer. chapter10eted ppt Open tile chapter18 egitnd(1).ppt Ciosn file |||
R'R?CHOH-CR°R* R'R?C=CR®R* What should orientation of each substituent in reactant to convert it into product alkene? What is importance of their specific orientation?
A7. Which of the following molecules represents the most stable conformation of cyclohexanol? A В C ОН HO- HO. ОН
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: CN 1) NaCN 2) H+ OH 1) NaBH4 2) H3O+ OH Group -H -CN A Value (kcal/mol) Defined as 0 0.2 kcal/mol -OH 1.0 kcal/mol c. For any products that do have the most stable conformation, does our understanding of the mechanism allow for ‘thermodynamic control'? d. If one of the products is not the most stable, can you explain the observed product based on ‘kinetic control'? (Does the most easily formed transition state result in the observed product?) Consider the chair-like conformation of the starting material.