(a) Which of the following are requirements for anionic polymerization?
1-A double bond
2- End groups which can react by releasing a small molecule
3- A strong base to initiate the reaction
4- A strong acid to initiate the reaction
5- An electron-withdrawing group near the double bond
(b) Which of the following groups are indicative of anionic polymerization?
1-F
2- Cl
3- 3
4- H
5- CH2CH3
To determine the requirements for anionic polymerization, we can go through each option and see which ones are correct.
1-A double bond: This is not a requirement for anionic polymerization. Anionic polymerization typically occurs through the initiation and propagation of anionic species, which can be generated by other means, not necessarily involving a double bond. Therefore, this option is not correct.
2- End groups which can react by releasing a small molecule: This is a requirement for anionic polymerization. Anionic polymerization occurs by the initiation of anionic species and the subsequent propagation through the reaction with monomers that have end groups capable of releasing a small molecule like a proton or a leaving group. Therefore, this option is correct.
3- A strong base to initiate the reaction: This is a requirement for anionic polymerization. Anionic polymerization typically starts with the initiation by a strong base that generates the initial anionic species from a monomer or an initiator. Therefore, this option is correct.
4- A strong acid to initiate the reaction: Anionic polymerization is not initiated by a strong acid. It typically requires a strong base. Therefore, this option is not correct.
5- An electron-withdrawing group near the double bond: This is not a requirement for anionic polymerization. While an electron-withdrawing group near a double bond may affect the reactivity of the monomer, it is not necessary for anionic polymerization to occur. Therefore, this option is not correct.
Therefore, the correct requirements for anionic polymerization are:
2- End groups which can react by releasing a small molecule
3- A strong base to initiate the reaction
Next, let's determine the groups that are indicative of anionic polymerization.
1-F: Fluorine (F) is not typically indicative of anionic polymerization. Therefore, this option is not correct.
2- Cl: Chlorine (Cl) is not typically indicative of anionic polymerization. Therefore, this option is not correct.
3- 3: An ester group, represented by 3, is often indicative of anionic polymerization. The ester end groups can react and release a small molecule during the polymerization process. Therefore, this option is correct.
4- H: Hydrogen (H) is not typically indicative of anionic polymerization. Therefore, this option is not correct.
5- CH2CH3: An alkyl group, represented by CH2CH3, is not typically indicative of anionic polymerization. Therefore, this option is not correct.
Therefore, the correct group indicative of anionic polymerization is:
3- 3