organic chem 5-6 Flashcards
what is a nucleophile?
electron pair donor
what is an electrophile?
electron pair acceptor
what reactions do alkanes get involved in as they are no very reactive?
radical reactions
initiation:
Cl2 ——> 2Cl*
propagation:
Cl* + CH4 —>CH3* + HCl
Cl2 + CH3* —> CH3Cl + Cl*
RADICALS USED and
then RE-GENERATED
Free radicals are very reactive because having a single electron is unstable.
propagation:
Cl* + CH4 —>CH3* + HCl
Cl2 + CH3* —>CH3Cl + Cl*
termination:
Cl* + Cl* —> Cl2
Cl* + CH3* —>CH3Cl
CH3* + CH3* —> C2H6
Removing the reactive free radicals brings an end to the reaction.
This is not very likely at the start of the reaction because of low concentration.
Reaction gives mixtures of products
what does hydrogenation leave to?
trans-double bonds in carbon chains: trans-fats
which fats are good?
unsaturated fats: liquid at room temp
what is oleic acid?
cis fatty acid found naturally in olive oils
what are geometric cis/trans isomers?
cis: substituents are on one side of pi bond
trans: substituents are on different sides of pi bond
what happens if the atoms attached to the c=c bond are different how do you distinguish E and Z isomers?
YOU LOOK AT THE ATOMIC NUMBERS OF THE ATOMS ATTACHED TO THE C=C
-higher 2 atomic numbers are used to find if its on the same side (E) or opposite (E)
are cis alkenes or trans alkenes more stable? why?
trans alkenes are more stable
cis alkenes are usually less stable due to steric strain (repulsion between electrons in atoms that are not directly bonded to each other). but since they are close to each other in cis they repel each other.
which is stronger pi or sigma bond?
The strength of a bond is dependent on the extent of overlapping. In the case of the sigma bond, the overlapping of orbitals takes place to a larger extent. Hence, the sigma bond is stronger in comparison to the pi bond because, in π bond, the extent of overlapping occurs to a smaller extent
are alkenes reactive?
c=c electron rich and donate electron pair (nucleophilic)
the pi bone is weaker than sigma bond and pi bond attacks electrophile (acceptor).
alkenes are involved in addition reaction.
why is H always added to the less substituted end of the double bond?
this is a more stable carbocation that the other way round
what is elimination?
removal of atoms and addition is the opposite
what makes a carbocation stable?
the more carbons that are attached to the c+ makes it more stable.
tertiary most stable
secondary
primary least stable
