Further organics Flashcards
delocalised model of benzene
the p-orbital of the 6 C overlap to form a delocalised π system.
Electron density
a representation of the probability of finding an electron at a specific point around an atom/ molecule.
electron-donating groups
donate e- into ring when attached to C and are 2,4 directing
define
electron withdrawing groups
groups which pull electron density away from ring, and 3 directing
Halogen carrier
A lewis acid that can bind to a halogen molecule, weakening the halogen bond to form a electrophile
What does phenol not react to?
Carbonates
Kekule’s Benzene Model
model of benzene which contains C=C and C-C bonds
3 evidence of the delocalised model
- bond length
- enthalpy change of hydrogenation
- resistance to reaction
3 steps to general electrophilic sub. of benzene
- generation of electrophile
- substitution
- catalyst reformation
Effect of addition reaction of benzene
- aromaticity is lost
- stability of the ring is lost
electrophile for nitration of benzene
NO2 +
Halogen carriers for halogenation of benzene
AlCl3
FeBr3
4 types of electrophilic substitution of benzene
- halogenation
- nitration
- Acylation (COCl)
- alkylation (CH3)
why is phenol more reactive than benzene
- greater charge density
- more suspetible to electrophile attack
Directing points
of electron-donating groups
2,4,6
Directing points of
electron-withdrawing groups
3
3 E.g. of electron-donating group
CH3 , OH , NH3
Eq. for
formation of Acyl chloride
Carboxylic acid +
Carboxylic acid +
How to make ester with phenol
acyl chloride
NOT carboxylic acid
What is acyl chloride more reactive than?
- acid anhydride
- COOH
- OH
4 reagents that reacts with
acyl chloride
state product as well …
+ Alcohol -> ester
+ water -> COOH
+ ammonia -> 1’ amine
+ 1’ amine -> amide
what is the product when
acid anhydride + alcohol
carboxylic acid
+ ester
Which is the most efficient way to produce
ester
+ why?
acid anhydride + alcohol
as it’s irreversible
Define chiralty
An isomerism when C is bonded to 4 different groups
How to form amide
acyl choride
+
amine
How to name 2’ amine/amide
Suffix - side attached to C=O
Preffix - side attached to N-H
(+ N- )
preffix = stuff substituted on Nitrogen
Name below
N-methly ethanamide
Methods to extend backbone
(aliphatic)
- haloalkane + NaCN
- carbonyls + NaCN + H+
2 Reactions to eliminate
nitrile group
name products
- reduction -> Amine
- hydrolysis -> Alcohol
Extend backbone
for aromatic
- acylation
- alkylation
Eq for hydrolysis of nitrile
Eq. for the reduction of
nitrile
5 steps for
recrytallisation
- dissolve in min. vol. of hot solvent
- let it cool
- filter with vaccum filtration
- wash with cold solvent
- let it dry
2 steps for
nitrobenzene -> phenyl amine
- Sn + HCl (conc.)
- NaOH
synthesis route
reduction of carbonyls
reagent + condition
NaBH4 + H2O
Eq. for
formation of amine
from haloalkane
Haloalkane + ethanoic ammonia
->
amine + HX
reagent needed
nitrile -> amine
H2 + Ni
Product for alkali hydrolysis
ester / amide
Carboxylate salt
+
Alcohol / amine
Reagents for alkylation
Haloalkane + halogen carrier
Reagent for aclylation
Acyl chloride
+
halogen carrier
Test for carbonyls
- Add 2,4 DNP
positive = yellow/orange p.p.
Test for aldehyde
- tollen’s reagent
silver p.p.
Test for haloalkane
- AgNO3 + NH3
same color for p.p. in halogen tests
Range for Rf value
0< Rf < 1
4 functional groups that make molecule **polared **
- OH
- C=O
- COOH
- NH2
what does retention time tell
In gas chromo
the time for sample to react detector
Shorter time
= more soluble in mobile phase
= less soluble in liquid phase
What are GC and TLC for
GC - volatile liquid / gases
TLC - solids
What is TMS
proton NMR
standard for chemical shifts measurements
proton NMR
What is CDCl3 and its purpose?
- deuterated solvents
dissolve organic molecules without hydrogen
3 things to consider when observing proton NMR spec
- area under
- shifts
- coupling
What does not couple
proton NMR
- equivilent H
- OH
- NH2
Purpose of
proton exchange
removes OH and NH peaks
How to do proton exchange ?
- do normal NMR
- add D2O
- redo NMR
[replaces H in OH/NH2 to OD/ND2]
no. of peaks if
1/2/3
non-equivilent H next door
2 peaks (d, doublet)
3 peaks (t, triplet)
4 peaks (q, quartet)
Define enantiomer
non-superimposable mirror image
