Formation of Alkenes

Question 1

What is formed when a Hydrogen and a Halogen (or H₂O) on adjacent carbons leave?

Answer 1

Alkenes

Question 2

Is NaOH a catalyst?

Answer 2

No

Question 3

Briefly, what are substitution reactions?

Answer 3

When two reactions swap parts to give a new product

Question 4

Is H₂SO₄ a catalyst?

Answer 4

Yes

Question 5

What are rearrangement reactions?

Answer 5

Where one reactant rearranged its bond and atoms to give the opposite isomer

Question 6

What type of reactions to alkyl halides and alcohols undergo to form an alkene?

Answer 6

Elimination reactions

Question 7

What type of alkyl halides undergo the fastest elimination reactions?

Answer 7

Tertiary halides

Question 8

Which product will always form preference?

Answer 8

The more stable

Question 9

What does Zaitsev’s Rule state?

Answer 9

In an elimination reaction, the more highly substituted alkene product predominates

Question 10

Are cis and trans isomers equally stable?

Answer 10

No

Question 11

What occurs in elimination reactions?

Answer 11

One reactant splits into two products

Question 12

What is the formation of the products dependent on in any reaction?

Answer 12

How stable the transition state is (and hence the activation energy)

Question 13

What are elimination reactions considered to be the opposite of?

Answer 13

Addition reactions

Question 14

What effect do alkyl substituents bonded to the sp² carbons of an alkene have?

Answer 14

A stabilising effect

Question 15

What are addition reactions?

Answer 15

Where two reactants combine to form one new product

Question 16

Why are trans isomers more stable than cis isomers?

Answer 16

They have less steric strain

Question 17

In an alkyl halide, where does the double bond form as a result of an elimination reaction?

Answer 17

In between the carbons that had the eliminated hydrogen and halogen

Question 18

What is the product of elimination reactions involving alkyl halides and alcohols?

Answer 18

Alkenes

Question 19

How can transition states be used to determine which product will form predominantly?

Answer 19

Any reaction that forms a more stable transition state will occur fastest and will result in that product forming predominantly

Question 20

How does the number of alkyl substituents bonded to the sp2 carbon of an alkene effect the stability?

Answer 20

The more alkyl substituents bonded to the sp² carbon of an alkene the greater the alkene’s stability

Question 21

Which is more stable: cis isomers or trans isomers?

Answer 21

Trans isomers.

Question 22

What is it important to do when determining the formation of alkenes?

Answer 22

Picture where the hydrogen atoms are so that you know what’s being eliminated and hence the location of the resultant double bond.