These are the homework exercises to accompany the Textmap for McMurry's Organic Chemistry textbook.
The heat of hydrogenation for allene is about 300 kJ/mol. Order a conjugated diene, a non-conjugated diene, and allene in increasing stability.
allene < non-conjugated diene < conjugated diene (most stable)
Give the 1,2 and the 1,4 products of the addition of one equivalent of HBr to 1,3-hexa-diene.
Look at the previous addition reaction of HBr with a diene. Consider the transition states, predict which of them would be the major products and which will be the minor.
The products i-iii all show a secondary cation intermediate which is more stable than primary. Therefore those would be major products and the iv product would be the minor product.
Consider the reaction with 1,3-buta-diene reacting with HCl. Propose a mechanism for the reaction.
Predict why the 1,4 adduct is the major product in this reaction compared to the 1,2.
Even though the cation would prefer to be in a secondary position in the transition state, the final product is less stable with a terminal alkene. Therefore the major product will be the 1,4 adduct.
Of the following dienes, which are S-trans and which are s-cis? Of those that are s-trans, are they able to rotate to become s-cis?
Predict the product of the following reaction.
A) s-trans, unable to rotate to become s-cis
C) s-trans, can rotate to become s-cis.
Draw a segment for the polymer that may be made from 2-tert-butyl-1,3-butadiene.
Propose the mechanism for the acid catalyzed polymerization of 2-methyl-1,3-butadiene.
The initial step is an addition of a hydrogen from the acid, followed by the polymerization.
What is the energy range for 300 nm to 500 nm in the ultraviolet spectrum? How does this compare to energy values from NMR and IR spectroscopy?
E = hc/λ
E = (6.62 × 10−34 Js)(3.00 × 108 m/s)/(3.00 × 10−7 m)
E = 6.62 × 10−19 J
The range of 3.972 × 10-19 to 6.62 × 10-19 joules. This energy range is greater in energy than the in NMR and IR.
Which of the following would show UV absorptions in the 200-300 nm range?
B and D would be in that range.