DJA 3). Mechanisms Flashcards Preview

Chemistry > DJA 3). Mechanisms > Flashcards

Flashcards in DJA 3). Mechanisms Deck (17):
1

free radical

A chemical species with an unpaired electron - usually highly reactive`

2

how many stages to free radical substitution

3

3

what are the stages of free radical substitution (short)

initiation propagation termination

4

initiation

free radicals are produced

Cl2 -------> •Cl + •Cl

 

5

Propagation

'Recycling the free radical'

a). Cl• + CH3CH--------> CH3•CH2 + HCl (dot usually above C)

b). CH3•CH2 + Cl2 -----> CH3CH2Cl + Cl •

 

free radical used and then reformed                                              

6

Termination

Two free radicals colliding

CH3•CH2 + Cl• ------->CH3CH2Cl

Cl• + Cl• --------> NO JUST REFORMS WITH UV LIGHT

CH3•CH2  + CH3•CH2 -------> CH3CH2CH2CH3

7

Further substitution

If Clis in excess then the product will react with more and more Cl2.

Then that new product wil react with more Cl2 and so on....

8

what is a nucleophile

a species that contains a lone pair of electrons 

9

3 examples of nucleophiles correctly written

 negative (xx) OH

(xx) NH3

negative (xx) CN

10

What happens during nucleophlic substitution

The nucleophile will swap places with another nucleophile on a molecule

11

Least reactive haloalkane

fluoro....

12

most freactive haloalkane

iodo.....

13

strongest haloalkane bond

fluoro....

14

weakest haloalkane bond

iodo...

15

explanation for strongest bond

shortest bond, electron pair in the bond is closest to the nucleus of F and there is little shielding therefore it is more strongly attracted

16

explanation for weakest bond

longest bond, electron pair in covalent bond is further away from the nucleus and there is more shielding so held less strongly

17

elimintaion 

what does negative (xx) OH act as

a base