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Is a Diels Alder reaction exothermic?

Answer 1

Yes, a Diels-Alder reaction is exothermic.

A Diels-Alder involves the reaction of a diene with a dienophile to form a cyclohexene derivative.

We can use bond dissociation energies (#"D"#) to calculate an approximate value of #"ΔH"# for this reaction.

Typical bond energies are: #"C-C"# = 347 kJ/mol and #"C=C"# = 614 kJ/mol

#ΔH_"rxn" = SigmaD_"reactants"color(white)(l) – SigmaD_ "products" = 3D_"C=C" +D_"C-C"color(white)(l) – D_"C=C"color(white)(l) –5D_"C-C"#

#= 2D_"C=C" color(white)(l)– 4D_"C-C" = "(2×614 -"color(white)(l)4×347) " kJ/mol" = "-160 kJ/mol"#

This is only a rough value, but it shows that the formation of four new #"C-C"# bonds makes the reaction quite exothermic.

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Answer 2

Ellie Adams

The Diels-Alder reaction is generally considered to be exothermic.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.