3Halogenoalkanes Flashcards
(25 cards)
What does anhydrous mean?
In the absence of water
What’s initiation
Radical forming step
What’s a nucleophile
Electron pair donor
What’s propogation
Spreading of the radicals
What’s a radical
Free radicals are reactive species with an unpaired electron and are drawn using a dot
What’s termination
All radicals are removed
What’s the order of the bond enthalpies from the strongest to the weakest?
C-F
C-Cl
C-Br
C-I.
Polarity also decreases
What are primary halogenoalkanes?
Have one R group attached to the carbon linked to the halogen
What’s a secondary halogenoalkane?
Two R groups are attached to the carbon linked to the halogen.
What’s a tertiary halogenolkane?
Have three R groups attached to the carbon linked to the halogen
Describe the solubility of a halogenoalkane
The polarity of the bond is not enough to make halogenoalkanes soluble in water, the main imfs are van der waals and dipole dipole attractions.
Describe the boiling point of a halogenoalkane
Increases with chain length
Increases going down the halogen group
What’s their trend in reactivity?
Reactivity increases going down the halogen group even though C-I is the least polar bond, this is due to their atom size.
What is nucleophillic substitution
When halogenoalkanes react with aqueous hydroxide ions
The nucleophile attacks the delta positive carbon and the bond between c and the halogen breaks and the halogen takes the electron.
The halogen results as a nucleophile.
What’s elimination?
When halogenoalkanes react with ethanolic hydroxide ions
The nucleophile attacks the hydrogen on the carbon adjacent to the carbon linked to the halogen. The C-H bond breaks and moves to the C=C as a double bond. This breaks the C- halogen bond and the electrons go to the halogen
The halogen results as a nucleophile
What are the products of nucleophillic substitution
Alcohol and a halogen ion
What’s the products of elimination?
An alkene, halogen ion and a water molecule.
The bond between the carbon and the halogen are always polar- which one is which?
C is always delta positive
Halogen is always delta negative
How must nucleophiles be drawn
Lone pair of electrons
Negative sign
What’s the most important thing to remember when dealing with arrows from nucleophiles?
The arrow should come from the lone pair
What are the conditions for nucleophillic substitution?
Low temp (warm or cool)
An ion to act as a nucleophile
Aqueous conditions
What are the conditions needed for elimination
Higher temp
Alcoholic- ethanolic acid
The ion acts as a base
What does ozone do?
Absorb uv radiation
Show an example of ozone depletion
03 + Cl* —> *OCl + 02
OCl + 03 —> 202 + Cl
Overall= 203 —> 302
