Alkenes (Organic) (complete)

Question 1

What are the two covalent bonds found within an organic compound/molecule? (pi bond and delta bond)

Answer 1

• delta covalent bond (electrons between the two atoms)
• pi covalent bond (electrons above and below the plane of the 6 central atoms (C and Hs) formed from overlap of p-orbitals on C atoms).

Question 2

What is Stereoisomerism?
What is the criteria for geometric isomerism?

Answer 2

• Molecules with the same molecular and structural formula but different arrangement of atoms in space.
• Criteria:
  > must have a C=C bond.
  > different groups attached to each C atom in C=C bond.

Question 3

Name the two types of geometric isomerism.

Answer 3

• E-isomerism: the highest priority groups are opposite.
• Z-isomerism: the highest priority groups are on the same side.

Question 4

What Alkene reaction will occur with aqueous Bromine?

Answer 4

• Electrophile Addition
• Sketch 1:
  1 - Curly arrow from C=C bond to Br atom on approaching Br — Br molecule.
  2 - Curly arrow from Br — Br bond to other Br atom.
• Sketch 2: (Br now on one Carbon atom, other Carbon atom = C+)
  1 - Curly arrow from Br- lone pair to C+ ion.

Question 5

What Alkene reaction will occur with HBr?

Answer 5

• Electrophilic addition.
• Sketch 1:
  1 - Curly arrow from C=C bond to H in H—Br.
  2 - Curly arrow from bond in H—Br to Br.
• Sketch 2: (H now joined on a C atom either side of C=C bond)
  1 - Curly arrow from lone pair on B- ion to C+ carbocation.

Question 6

What Alkene reaction will occur with cold, concentrated H2S04?

Answer 6

• Electrophilic addition.
• Sketch 1:
  1 - Curly arrow from C=C bond to H in OH in H2SO4.
  2 - Curly arrow from OH bond in H2SO4 to the O that the H is being removed from.
• Sketch 2:
  1 - Curly arrow from lone pair on O- ion in HS04- to C+ carbocation.

Question 7

What Alkene reaction will occur with H20 (+ strong acid)?

Answer 7

• Electrophilic addition.
• Sketch 1:
  1 - Curly arrow from C=C bond to H+ donated from acid.
• Sketch 2:
  1 - Curly arrow from lone pair on O in H2O to C+ carbocation.
• Sketch 3:
  1 - Curly arrow from bond between OH in H2O that’s now bonded onto Carbon in alkane to O+ in H2O.
  2 - (H ion drops off)

Question 8

Describe the different between major product formed and minor product formed during alkene reactions.

Answer 8

• Major product - formed the most, as formed using a more stable carbocation during intermediate.
• Minor product - formed the least, formed using a less stable carbocation during intermediate.