82,799 students have used Clutch for Orgo
97% got a better grade
3,804 minutes of Organic Chemistry videos

436 Video Solutions

A mixture of three alkenes (A, B, and C) was obtained by dehydration of 1,2-dimethyl cyclohexanol. The composition of the mixture was A (3%), B (31%), and C (66%). Catalytic hydrogenation of A, B, or C gave 1,2-dimethylcyclohexane. The three alkenes can be equilibrated by heating with sulfuric acid to give a mixture containing A (0%), B (15%), and C (85%). Identify A, B, and C.   

Watch Solution

(a) Suggest an explanation for the fact that 1-methylcyclopropene is some 42 kJ/mol (10 kcal/mol) less stable than methylenecyclopropane. 

Watch Solution

Choose the more stable alkene in each of the following pairs. Explain your reasoning.

 (e) ( Z )-Cyclooctadecene or ( E )-cyclooctadecene 

Watch Solution

Choose the more stable alkene in each of the following pairs. Explain your reasoning. 

(d) ( Z )-Cyclononene or ( E )-cyclononene 

Watch Solution

Choose the more stable alkene in each of the following pairs. Explain your reasoning. 

Watch Solution

Compounds A and B are isomers of molecular formula C9H19Br. Both yield the same alkene C as the exclusive product of elimination on being treated with potassium  tert -butoxide in dimethyl sulfoxide. Hydrogenation of alkene C gives 2,3,3,4-tetramethylpentane. What are the structures of compounds A and B and alkene C?    
 

Watch Solution

On being heated with a solution of sodium ethoxide in ethanol, compound A (C7H15Br) yielded a mixture of two alkenes B and C, each having the molecular formula C7 H14 . Catalytic hydrogenation of the major isomer B or the minor isomer C gave only 3-ethylpentane. Suggest structures for compounds A, B, and C consistent with these observations.    
 

Watch Solution

The iodination of ethylene at 25°C is characterized by the thermodynamic values shown.

H2C = CH2(g) + I2(g) ⇌ lCH2CH2l(g)     ΔH° = - 48 kJ/mol; ΔS° = - 0.13 kJ/mol

(c) What happens to K as the temperature is raised?

Watch Solution

Choose the more stable alkene in each of the following pairs. Explain your reasoning. 

(b) Isopropenylcyclopentane or allylcyclopentane 

Watch Solution

The iodination of ethylene at 25°C is characterized by the thermodynamic values shown.

H2C = CH2(g) + I2(g) ⇌ lCH2CH2l(g)     ΔH° = - 48 kJ; ΔS° = - 0.13 kJ/K

(b) Is the reaction exergonic or endergonic at 25°C?

Watch Solution

Choose the more stable alkene in each of the following pairs. Explain your reasoning. 

(a) 1-Methylcyclohexene or 3-methylcyclohexene 

Watch Solution

The iodination of ethylene at 25°C is characterized by the thermodynamic values shown.

H2C = CH2(g) + I2(g) ⇌ lCH2CH2l(g)     ΔH° = - 48 kJ; ΔS° = - 0.13 kJ/K

(a) Calculate ΔH° and K at 25°C.

Watch Solution

Match each alkene with the appropriate heat of combustion:

Heats of combustion (kJ/mol): 5293; 4658; 4650; 4638; 4632

Heats of combustion (kcal/mol): 1264.9; 1113.4; 1111.4; 1108.6; 1107.1 

 (a) 1-Heptene 

(b) 2,4,-dimethyl-1-pentene

(c) 2,4,-dimethyl-2-pentene

(d) (Z)-4,4-dimethyl-2-pentene

(e) 2,4,4-trimethyl-2-pentene

Watch Solution

Complete the following table by adding + and - signs to the  ΔH° and  ΔS° columns so as to correspond to the effect of temperature on a reversible reaction.      

 

Watch Solution

A growth hormone from the cecropia moth has the structure shown. Express the stereochemistry of the double bonds according to the EZ system. 

Watch Solution

The sex pheromone of the honeybee is the  E stereoisomer of the compound shown. Write a structural formula for this compound. 

Watch Solution

Hydrogenation of 3-carene is, in principle, capable of yielding two stereoisomeric products. Write their structures. Only one of them was actually obtained on catalytic hydrogenation over platinum. Which one do you think is formed?

Watch Solution

Write bond-line formulas for each of the following naturally occurring compounds, clearly showing their stereochemistry.

The worm in apples is the larval stage of the codling moth. The sex attractant of the male  moth is the 2Z,6E stereoisomer of the compound shown.

Watch Solution

Nerol is a naturally occurring substance that is a stereoisomer of geraniol. Write its structure. 

Watch Solution

Catalytic hydrogenation of 1,4-dimethylcyclopentene yields a mixture of two products. Identify them. One of them is formed in much greater amounts than the other (observed ratio 10:1). Which one is the major product? 

Watch Solution

Write bond-line formulas for each of the following naturally occurring compounds, clearly showing their stereochemistry

Geraniol: a hydrocarbon with a rose-like odor present in the fragrant oil of many plants (including geranium flowers). It is the E isomer of

Watch Solution

Compound A undergoes catalytic hydrogenation much faster than does compound B. Why? 

Watch Solution

(a) The sex attractant of the Mediterranean fruit fly is ( E )-6-nonen-l-ol. Write a structural formula for this compound, showing the stereochemistry of the double bond. 

Watch Solution

Grandisol is one component of the sex attractant of the boll weevil. Write a structural formula for grandisol given that R in the structure shown is an isopropenyl group.

Watch Solution

Alkyl isothiocyanates are compounds of the type RN=C=S. Write a structural formula for allyl isothiocyanate, a pungent-smelling compound isolated from mustard.

Watch Solution