3.3.7 - Optical Isomerism + naming Flashcards
aldehyydes functional group prefix and suffix
. O
||
—- C — H
suffix -al
prefix formyl
if 2 aldehyde groups then how is naming different
If two aldehyde groups
then di is put before –al
and an e is added to
the stem.
eg pentanedial
ketones func group prefix and suffix
. O
||
—-C—–
suffix* -one
prefix oxo
When ketones have 5C’s or more in a chain how is naming different
When ketones have 5C’s or more
in a chain then it needs a number
to show the position of the double
bond. E.g. pentan-2-one
if 2 ketone groups how is naming different
If two ketone groups then
di is put before –one and
an e is added to the stem
eg pentanedione
prefix oxo should be used for compounds…
The prefix oxo- should be
used for compounds that
contain a ketone group in
addition to a carboxylic acid
or aldehyde
2-oxopropanoic acid
carboxylic acid func group and suffix
. O
||
—-C—-OH
suffix -oic acid
If there are carboxylic acid groups on both ends of the
chain then it is called a …
dioic acid with an e after stem eg ethanedioic acid
nitriles func group, suffix and prefix
—C triple bond N
suffix -nitrile
prefix cyano
how to name nitrile w 4 carbons
butanenitrile
C from CN is included in the name
amines func group, suffix and prefix
. |
|
—–C—-NH2
|
|
suffix* - -yl - amine
prefix amino
2 ways of naming amine w 3 carbons for example
The exam board tend to use the common
version where the name stem ends in -yl
propylamine.
Another version of the same chemical is
propan-1-amine. (
when is the prefix amino used when naming amines
If there is another priority
functional group as well
as the amine group then
the prefix amino is used.
. H2N O
\ //
CH—C
/ \
H3C O - H
2-aminopropanoic acid.
if amine is secondary how is naming different
If the amine is secondary and has two alkyl
groups attached to the nitrogen, then each chain
is named and the smaller alkyl group is preceded
by an –N which plays the same role as a number
in positioning a side alkyl chain
eg
CH3CH2CH2NHCH3 N-methylpropylamine (common name)
N-methylpropan-1-amine (other name)
if amine is tertiary how is naming different
If a tertiary amine similar rules apply, and
each alkyl side group is given an N
eg CH3CH2CH2 -N- CH3
|
CH3
if 2 amine groups how is naming different
diamine is suffix
eg hexane-1,6-diamine
esters func group, suffix and prefix + example
. ||
—C—O—-
-yl –oate
methyl ethanoate
Esters have two parts to their names
The bit ending in –yl comes from the _______ that has formed it and is
next to the single bonded ________. The bit ending in –anoate comes
from the _______. (This is the chain including the C=O bond)
Esters have two parts to their names
The bit ending in –yl comes from the alcohol that has formed it and is
next to the single bonded oxygen The bit ending in –anoate comes
from the carboxylic acid. (This is the chain including the C=O bond)
acyl chloride func group suffix and example
. O
//
— C -oyl chloride
\
Cl eg ethanoylchloride
amide func group, suffix and example
. O
//
— C -amide
\
NH2 ethanamide
how are secondary and tertiary amides named differently
Secondary and tertiary amides
are named differently to show the two (or three) carbon chains.
The smaller alkyl group is
preceded by an –N which plays the same role as a number in positioning a side alkyl chain
name this
O
||
H3C—CH2—C—NH—CH3
N-methylpropanamide
name this
O CH3
|| | H3C---CH2---C---N---CH3
N,N-dimethylpropanamide
acid anhydrides func group, suffix and example
. O
//
R — C
\
O
/
R — C
O
-oic anhydride
Ethanoic anhydride
why is ethanoic anhydride named the way it is
It is ethanoic
because it is two ethanoate
groups joined together.
. O
//
CH3–C
\
O
/
CH3 – C
O
if the alkyl groups are different how is the acid anhydride named
If the alkyl groups are of
different lengths then
each one is named
e.g. ethanoic propanoic
anhydride
. O
//
CH3– C
\
O
/
CH3–CH2 – C
O
order of priority when multiple func groups
Carboxylic acids >carboxylic acid derivative>nitriles>aldehydes>ketones>alcohols>amines>alkenes>halogenoalkanes
when compounds have more than one func group ______ priority takes _____ with all others taking _____ form
when compounds have more than one func group highest priority takes suffix with all others taking prefix form
structural isomers def
same molecular formula different
structures (or structural formulae)
Structural isomerism can arise from
*Chain isomerism
*Position isomerism
*Functional group isomerism
what kind of isomers would aldehydes and ketones be classed as
functional group isomers
define stereoisomerism
stereoisomers have the same structural formula with different arrangment of atoms
2 types of steroisomerism
e-z isomerism
optical isomerism
optical isomerism is a type of of stereoisomerism where….
optical isomerism is a type of of stereoisomerism where molecules have the same molecular formula but a different spatial arrangment of atoms in space
optical isomerism occurs in …
Optical isomerism occurs in carbon compounds with 4
different groups of atoms attached to a carbon (called
an asymmetric carbon).
what is a chiral carbon
A carbon atom that has
four different groups
attached is called a chiral
(asymmetric) carbon
atom
4 groups are arranged _____ around carbon atom
These four groups are arranged
tetrahedrally around the carbon.
presense of chiral centre leads to the presense of 2 ….
presense of chiral centre leads to the presense of 2 possible isomers that are mirror images of eachother (optical isomers)
An ________ carbon atom is _________ and gives rise to ______ ______ (________), which exist as ___ ______ __________ mirror images and differ in their effect on _______ ________ _____. A mixture of ________ amounts of enantiomers is called a ______ _______ (racemate).
An asymmetric carbon atom is chiral and gives rise to optical isomers(enantiomers), which exist as non super-imposable mirror images and differ in their effect on plane polarised light. A mixture of equal amounts of enantiomers is called a racemic mixture (racemate).
Two compounds that are optical isomers of
each other are called…
enantiomers
Optical isomers have similar …..
physical and chemical properties
enantiomers are unique due to their effect…
enantiomers are unique due to thier effect on plane polarised light. each entantiomers causes the rotation of plane polarised lightby 90 degrees in opposite diretions
enantiomers exist as
non super-imposable mirror images and differ in their effect on plane polarised light
what is a racemate/racemic mixture ?
A mixture containing a 50/50 mixture of the
two isomers (enantiomers) is described as
being a racemate or racemic mixture.
how is a racemate formed
A racemate will be formed in a reaction
mechanism when a reactant or intermediate
has a trigonal planar group in the molecule
is approached from both sides by an attacking
species
why does a racemate form
There is an equal chance of
either enantiomer forming so
a racemate forms. No
optical activity is seen
