M3L8 Addition Reactions and Polymers

Complete the flowchart below to show the organic product formed in the addition reaction of methylpropene with H2/Ni.

• 2-methylpropane (C4H10)

• 2-methylpropene (C4H8)

• butane (C4H10)

• propane (C3H8)

Complete the flowchart below to show the organic product formed in the addition reaction of methylpropene with Br2.

• 2,3-dibromo-2-methylpropane (C4H8Br2)

• 1,2-dibromo-2-methylpropane (C4H8Br2)

• 2-bromo-2-methylpropane (C4H9Br)

• 1,1-dibromo-2-methylpropane (C4H8Br2)

Complete the flowchart below to show the organic product(s) formed in the addition reaction of methylpropene with HBr. (Refer to the diagram showing methylpropene and reagents. Note: mixture of isomers.)

• 2-bromo-2-methylpropane and 1-bromo-2-methylpropane (mixture of isomers)

• 2-bromo-2-methylpropane only

• 1-bromo-2-methylpropane only

• 2-bromopropane and 1-bromopropane (mixture of isomers)

Curly arrows are used in reaction mechanisms to show the movement of electron pairs during chemical reactions.

Which of the following best outlines the mechanism for the addition reaction of methylpropene with bromine, including the use of curly arrows and relevant dipoles?

• Curly arrows show the movement of electron pairs from the double bond of methylpropene to a bromine atom, forming a bromonium ion intermediate, with Brδ+ and Brδ− dipoles indicated.

• Curly arrows show the movement of electron pairs from the bromine molecule to the methyl group, forming a carbocation intermediate, with no dipoles indicated.

• Curly arrows show the movement of electron pairs from the methyl group to the double bond, forming a free radical intermediate, with Br2 as a neutral molecule.

• Curly arrows show the movement of electron pairs from the double bond to the hydrogen atom of HBr, forming a methyl anion intermediate, with Br2 as a neutral molecule.

Draw two repeating units of the polymer produced by the following alkene: propene.

• The repeating unit for polypropene is: -[CH2-CH(CH3)]- (drawn twice in sequence).

• The repeating unit for polypropene is: -[CH2-CH2]- (drawn twice in sequence).

• The repeating unit for polypropene is: -[CH2-CHCl]- (drawn twice in sequence).

• The repeating unit for polypropene is: -[CH2-CH(CN)]- (drawn twice in sequence).

Draw two repeating units of the polymer produced by the following alkene: but-1-ene.

• The repeating unit for poly(but-1-ene) is: -[CH2-CH(C2H5)]- (drawn twice in sequence).

• The repeating unit for poly(but-1-ene) is: -[CH2-CH(CH3)]- (drawn twice in sequence).

• The repeating unit for poly(but-1-ene) is: -[CH2-CH2]- (drawn twice in sequence).

• The repeating unit for poly(but-1-ene) is: -[CH2-CH(C3H7)]- (drawn twice in sequence).

Name the following polymer and draw the monomer from which the polymer is made:

• The polymer is poly(2-methylpropene) (polyisobutylene). The monomer is 2-methylpropene (isobutylene): CH2=C(CH3)2.

• The polymer is poly(ethene) (polyethylene). The monomer is ethene: CH2=CH2.

• The polymer is poly(propene) (polypropylene). The monomer is propene: CH2=CHCH3.

• The polymer is poly(styrene). The monomer is styrene: C6H5CH=CH2.

Name the following polymer and draw the monomer from which the polymer is made:

• The polymer is poly(vinyl chloride-co-propylene). The monomers are propene (CH2=CH-CH3) and vinyl chloride (CH2=CHCl).

• The polymer is poly(ethylene-co-propylene). The monomers are ethene (CH2=CH2) and propene (CH2=CH-CH3).

• The polymer is poly(styrene-co-vinyl chloride). The monomers are styrene (C6H5CH=CH2) and vinyl chloride (CH2=CHCl).

• The polymer is poly(vinyl chloride-co-ethylene). The monomers are ethene (CH2=CH2) and vinyl chloride (CH2=CHCl).

Given the following chemical reaction sequence involving methylpropane and the addition of Br2 and HBr, draw the displayed formulae for all the products formed. (You may use skeletal or displayed formulae. Ignore molecular formulae.)

• The correct structures are: 1) methylpropane (CH3)3CH, 2) 1,2-dibromo-methylpropane (CH2BrCBr(CH3)2), 3) 1-bromo-methylpropane (CH2BrCH(CH3)2), 4) 2-bromo-methylpropane (CH3CBr(CH3)2).

• The correct structures are: 1) methylpropane (CH3)3CH, 2) 1,1-dibromo-methylpropane (CH2Br2C(CH3)2), 3) 1-bromo-methylpropane (CH2BrCH2CH3), 4) 2-bromo-methylpropane (CH3CHBrCH2CH3).

• The correct structures are: 1) methylpropane (CH3)3CH, 2) 2,2-dibromo-methylpropane (CHBr2C(CH3)2), 3) 1-bromo-methylpropane (CH2BrCH2CH3), 4) 2-bromo-methylpropane (CH3CHBrCH2CH3).

• The correct structures are: 1) methylpropane (CH3)3CH, 2) 1,3-dibromo-methylpropane (CH2BrCH2CHBrCH3), 3) 1-bromo-methylpropane (CH2BrCH2CH3), 4) 2-bromo-methylpropane (CH3CHBrCH2CH3).

In the electrophilic addition of bromine to an alkene, draw the curly arrow from the double bond to Brδ+ and from the Br–Br bond pair to Brδ– in the first step. What do these curly arrows represent?

• The curly arrows represent the movement of electron pairs: one from the double bond to Brδ+ and one from the Br–Br bond to Brδ–.

• The curly arrows represent the movement of protons: one from the double bond to Brδ+ and one from the Br–Br bond to Brδ–.

• The curly arrows represent the movement of single electrons: one from the double bond to Brδ+ and one from the Br–Br bond to Brδ–.

• The curly arrows represent the movement of nuclei: one from the double bond to Brδ+ and one from the Br–Br bond to Brδ–.