Solutions Assignment 9 - University of Texas at H R Isotactic Syndiotactic O O H3C ... 2. O O O O H3C H3C H3C H3C H 3C H3C H H H H H H R O O O O H ... Solutions_Assignment 9 Author: WillsonWeb

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    29-May-2018

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  • Assignment 9 Odian 8.1 b. No stereoisomers e.

    Me H Me HH Me H Me

    H Et H EtEt H Et H

    Me Me Me MeH H H H

    Et Et Et EtH H H H

    Me H Me HH Me H Me

    Et H Et HH Et H Et

    Me Me Me MeH H H H

    H H H HEt Et Et H

    n.

  • O

    O

    O

    O

    H3C

    H3C

    H3CH

    H

    H

    R

    O

    O

    O

    O

    H3C

    H

    H3CH

    CH3

    H

    R

    Isotactic

    Syndiotactic

    O

    O

    H3C

    H CH3

    H

    u. See page 632, change cyclopentane to cyclohexane and substitute a methyl in place of the proton. Also possible through Ring Opening Polymerization are both the cis- and trans- isomers of poly(1-methyl-1-hexene-1,6-diyl). 2.

  • O

    O

    O

    O

    H3C

    H3C H3C

    H3C H3C

    H3C

    H

    H H

    H H

    H

    R

    O

    O

    O

    O

    H

    H3C H3C

    H H

    H3C

    CH3

    H H

    CH3CH3

    H

    R

    O

    O

    O

    O

    H

    H3C H

    H3C H

    H3C

    CH3

    H CH3

    H CH3

    H

    R

    O

    O

    O

    O

    H3C

    H3C H

    H H3C

    H3C

    H

    H CH3

    CH3H

    H

    R

    Threodiisotactic

    Erythrodiisotactic

    Threodisyndiotactic

    Erythrosyndiotactic

    Not drawn atactic. 3. C3H7 C3H7 C3H7 C3H7H H H H

    CH3 CH3 CH3 CH3H H H H 4.

  • 5. Anionic polymerizations are more sensitive to solvent effects than radical polymerization due to ion pairing. For each propagating anion in solution there is a counter cation. Solvents possessing lower solvation character will result in a tighter ion pairs. Tighter ion pairs effectively reduce the concentration of propagating species in the solvent. These effects may be exploited to aid in control of stereochemistry. Due to the lack of a counterspecies radical polymerizations are far less affected by solvent effects. 6. Introduction of the chlorine substituent removes electron density from the olefin through inductive effects thus causing the carbocation more difficult to form. When the carbocation is formed it is more electropositive and therefore less stable. 7. More electron donating species stabilizes the carbocation as discussed in #6. There are 2 styrene derivatives with electron donating groups (EDGs) and 1 with an electron withdrawing group (EWG). If we consider styrene as the basis to compare the other materials it is noted that the styrene derivatives with EDGs will polymerize faster and the lone EWG derivative will be slower. Thus the final ordering can be made by determining which EDG is stronger. In this case methoxy is a better EDG than methyl so the order of reactivity can be assigned as shown.

    OMe CH3 Cl

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