Reactivity Type of polymerization Groupa R only Group B and group c RR Stronger or weaker Group D RR, R Initiator should be stronger
Group A Group B and group C Group D R R R , R R R + , , >> >> Initiator should be stronger Stronger or weaker only Reactivity Type of polymerization
3. Initiator and initiation (1)alkali metal Lithium (Li a. Species Sodium(Na) b. Initiation Potassium(K) c. Solubility electron Na hccH CH-CH Na transfer dimerize Na CH-CH2 -CH2-CH Na radical couple
3. Initiator and initiation (1) alkali metal Lithium (Li) Sodium (Na) Potassium (K) a. Species b. Initiation c. Solubility - Na H2 C CH electron transfer CH2 CH Na+ + . e - Na - Na CH CH2 CH2 CH + dimerize + radical couple
Solubility of alkali metals K: soluble in ethers Li and Na dispersion homogeneous or heterogeneous insoluble in hydrocarbon Reaction on the surface adsorbtion reaction desorption
K: soluble in ethers Li and Na dispersion: insoluble in hydrocarbon Solubility of alkali metals homogeneous or heterogeneous Reaction on the surface adsorbtion reaction desorption
(2)Alkali metal complex a. Species Aromatic radical-anions: b. Initiation Sodium naphthalene c. Solubility Lithium naphthalene preparation a Na complex(greenish blue color) Alkali metal Aromatic compound initiator
(2) Alkali metal complex - Na Na + + [ ] e complex (greenish blue color) . preparation initiator a. Species b. Initiation c. Solubility Aromatic radical-anions: Sodium naphthalene Lithium naphthalene Alkali metal Aromatic compound