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Resonance stabilization of Active Center

Structure and Reactivity. Resonance stabilization of Active Center. Transition State Theory. AB * Activated complex. ΔE R A + B. P.E.

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Resonance stabilization of Active Center

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  1. Structure and Reactivity Resonance stabilization of Active Center Transition State Theory AB* Activated complex ΔER A + B P.E. ΔHR compound Increasing Separation of A & B

  2. Structure and Reactivity AB Morse curve P.E. A+B repulsion curve Increasing Separation of A & B ΔE1‡ > ΔE3‡ then Rexn III is less stable than Rexn I ΔHR3‡ < ΔHR1‡ R  P.E. ΔE1‡ R + M Reaction I R  ΔE3‡ Rs  + M Reaction III R  Increasing Separation of Reactant

  3. Structure and Reactivity Resonance stability of Active Center become primary Resonance stability ofMonomer become secondary

  4. Structure and Reactivity |-ΔH | ① > ② > ③ > ④ ΔE‡ ④ > ③ > ② > ① Surfing to the internet For further details about Free Radical Polymerization Click next homepage. http://www.chem.rochester.edu/~chem421/frfull.htm

  5. Structure and Reactivity II. Polar Effects Tend to cause alternation in a copolymerization i.e. for polar effects e : tendency to give monomer a polar effects Alfrey-Price Q,e scheme (Polarity Values)

  6. Structure and Reactivity Q-e scheme forecast randomness of copolymerization , As know r, prediction is possible to polar, resonance effect Guidance to chemists where P : active center reactivity Q : monomer reactivity i, j : active center, monomer, respectively

  7. Structure and Reactivity so that, this equation forecast Base materials use styrene : (arbitrary) fair results, but not absolute in predicting r using Q-e scheme. alternating tendency is correct

  8. Structure and Reactivity Active Center Reacting Ratios P-e scheme

  9. Structure and Reactivity The criticism againstQ-e scheme Reference state arbitrarily set. Alternating effect was observed due to fixed charges not due to the induced dipole Exercise) How to indicate Randoness of Copolymer with Q-e scheme ? We can forecast alternation or randomness through Q-e scheme, however, why can not forecast Blockcopolymerization? (algebraic standpoint) Surfing to the internet For further details about Free Radical Polymerization Click next homepage. http://www.kcpc.usyd.edu.au/resources/notes/gilbertnotes3.pdf

  10. Structure and Reactivity III. Steric Effects 1) 1,2-disubstituted ethylene do not homopolymerize readily 2). 1,1-disubstituted ethylene II. Polar Effects planar conformation tetrahedral conformation more reactive

  11. Structure and Reactivity 3) Cis-trans Effect The trans is stabilized the cis than thermodynamics(Heat of Hydrogenation) Planarity! Easier for trans than cis Steric Effect! Surfing to the internet For further details about Free Radical Polymerization Click next homepage. http://pslc.ws/macrog/lab/unit1.htm

  12. Structure and Reactivity Table 6-5 Rate Constants( ) for Radical-Monomer Reactionsa a values calculated from data in Table 3-11 and 6-2 and [66] 1,1-disubs. High reactive Mono subs. Tri subs. Trans 1,2 Cis 1,2

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