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If both substituents on one carbon atom of the double

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If both substituents on one carbon atom of the double bond are identical, the Z/E or cis / trans classification is not applicable. More information on alkene nomenclature can be found in sections 3.4-3.5 of J&F. a. 2-chloro-3-bromo-2-hexene b. 1-chloro-2-ethyl-1-butene c. 3,5-diethyl-2,6-diiodohepta-2,5-diene Draw the following two alkenes: The following unsaturated molecules can exist as configurational stereoisomers. For each of the following compounds, draw ALL possible double bond isomers and assign each one as an E or Z isomer. Indicate whether the following are E or Z isomers: b. 2-(prop-1-en-2-yl)but-2-enal O a. 3-( tert -butyl)-4-propylhepta-3,6-dien-1-yne ( Z )-1-chloro-3,4,5-trimethylhex-3-ene (2 E ,4 Z )-2-bromo-5-methylocta-2,4-diene Chem 33, Kanan & Stack, 2012, PS 3; pg 3
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6. Consider the following hydrogenation reaction--the addition of H 2 to a carbon-carbon multiple bond: H H H H + H 2 H 3 C CH 3 a. Determine the H rxn for the reaction above: H f ° of ethane –20.3 kcal mol -1 H f ° of ethene 12.5 kcal mol -1 b. The homolytic bond dissociation energy (BDE) of H 2 is 104 kcal mol -1 , which is the amount of energy needed to break H 2 into two hydrogen atoms ( i.e. each atom has one electron). Assuming that the average homolytic BDE for a C–H bond in ethane is 100 kcal mol -1 , estimate the energy required to break the π -bond in ethylene ( think about a thermodynamic cycle including the information in part a ) c. Estimate the rate of rotation around the double bond in ethylene at 300 K assuming that the barrier to rotation ( G ) is equal to the estimated π -bond BDE in ethylene from part b. How many years would one have to wait on average to see such a rotation at 300 K? Chem 33, Kanan & Stack, 2012, PS 3; pg 4
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b. Write out a balanced chemical reaction for the heat of combustion ( Δ H c °) of 1,4 pentadiene.
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