Download Unit One Part 2: naming and functional groups

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Unit One Part 2: naming and functional groups
• To write and interpret IUPAC names for small, simple molecules
• Identify some common functional groups found in organic molecules
O
H3C
N
CH3
N
N
H
O
N
S O
N
O
H3C
H3C
N
viagra™ (trade name)
sildenafil (trivial name)
5-(2-ethoxy-5-(4-methylpiperazin-1-ylsulfonyl)phenyl)-1-methyl-3-propyl-1Hpyrazolo[4,3-d] pyrimidin-7(6H)-one
dr gareth rowlands; [email protected]; science tower a4.12
http://www.massey.ac.nz/~gjrowlan
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Systematic (IUPAC) naming
PREFIX
PARENT
substituents / minor
functional groups
number of C
AND multiple bond
index
SUFFIX
principal functional
group
• Comprises of three main parts
• Note: multiple bond index is always incorporated in parent section
No. Carbons
Root
No. Carbons
Root
1
meth
6
hex
Bond
Multiple-bond
index
2
eth
7
hept
C–C
an(e)
3
prop
8
oct
C=C
en(e)
4
but
9
non
C C
yn(e)
5
pent
10
dec
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Systematic (IUPAC) naming: functional groups
Functional group
Structure
O
acid
R
O
anhydride
R
OH
O
O
O
acyl chloride
R
R
Cl
O
ester
R
OR
O
amide
nitrile
R
NH2
R
N
O
aldehyde
R
H
O
ketone
R
Suffix
Prefix
General form
–oic acid
–carboxylic acid
carboxy
R-COOH
–oic anhydride
–carboxylic anhydride
R-C(O)OC(O)-R
–oyl chloride
-carbonyl chloride
chlorocarbonyl
R-COCl
–oate
–carboxylate
alkoxycarbonyl
R-COOR
–amide
–carboxamide
carbamoyl
R-CONH2
–nitrile
cyano
R-C N
–al
–carbaldehyde
oxo
R-CHO
–one
oxo
R-CO-R
R
alcohol
R OH
–ol
hydroxy
R-OH
amine
R NH2
–amine
amino
R-NH2
ether
R
O
–ether
alkoxy
R-O-R
bromo
(halo)
R-Br
(R-X)
alkyl bromide
(alkyl halide)
R
R Br
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Nomenclature rules
1. Parent - root derived from number of carbon in longest unbranched chain
.containing functional group
CH3
CH3
H3C
H3C
CH3
5
4-methylheptane
4
OH
2
3
1
2-propyl-1-pentanol
2. Suffix - basic name derived by adding ending of major functional group (FG)
O
H3C
CH3
OH
O
H3C
NH2
3-methylbutanamide
butanoic acid
3. Position - position of FG denoted by Arabic numeral placed before whole
....name or just before ending. Numbering achieves lowest number for FG
O
H3C
CH3
2-pentanone
pentan-2-one
NOT 4-pentanone
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Nomenclature rules II
4. Prefix - substituents are designated by prefix & Arabic number indicating
....position (lowest possible numbering)
Cl
CH3
H3C
CH3
H3C CH3
2,2,5-trimethylheptane
NOT 3,6,6-trimethylheptane
CH3
H3C
CH3
CH3
8-chloro-2,3-dimethylnonane
NOT 2-chloro-7,8-dimethylnonane
5. FG - if more than one FG name & number based on principle FG. List of
....priorities given in course notes. Multiple bonds are added to parent (end),
....all others are prefixes
O
HO
O
OH
H3C CH3
5-hydroxy-2,2-dimethylpentanoic acid
H3C
CH3
OH
O
2-methyl-4-oxohex-2-enoic acid
6. Minor FG - halo-, nitro- (-NO2), nitroso- (-NO) & azo- (-N2-) are considered
....substituents & not FG for nomenclature only
7. Order - substituents are written in alphabetical order
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Examples: structure to name
OH
OH
O
H3C
N
H
H 3C
N
CH3
H
N-ethyl-3-hydroxy-5-methylhept-6-enamide
CH3
Step 1: root
OH
Step 7: complete
OH
O
H3C
N
H
hept
H3C
H3C
5
4
3
1
2
Step 5: substituents
(prefix)
OH
O
N
H
hept amide
O
N
CH3
H
3-hydroxy-5-methylhept-6-enamide
CH3
Step 2: suffix
OH
O
H3C
N
CH3
H
3-hydroxyhept-6-enamide
CH3
6
Step 3: multiplebond index
O
H3C
5
OH
2
1
O
N
4
2
H
hept-6-enamide
3
3
1
CH3
Step 4: functional
groups (prefix)
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Examples: name to structure
• Draw the structure for 4-ethyl-3-hydroxycyclohexanone (please)
O
draw the root
4-ethyl-3-hydroxycyclohexanone
add major functional group
4-ethyl-3-hydroxycyclohexanone
O
O
OH
H3C
add substituent
4-ethyl-3-hydroxycyclohexanone
H3C
add minor functional group
4-ethyl-3-hydroxycyclohexanone
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Functional groups: alkanes
• Saturated hydrocarbons - contain only C & H and no multiple bonds
• Non-cyclic alkanes have the formula CnH2n+2
H
H C H
H
methane
CH4
propane
C3H8
pentane
C5H12
cyclopentane
C5H10
CH4
• Alkanes are a little dull - used as solvents or burnt as fuel
• Methane is a fuel, a chemical feedstock & a green house gas
propane
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Functional groups: alkanes II
isooctane
2,2,4-trimethylpentane
C8H18
• Isooctane is used in petrol - branched structure means it burns smoothly
• Octane is a long change and burns explosively
• Octane number of petrol is based on isooctane = 100 & heptane = 1
Unleaded 91 petrol = 91% isooctane & 9% heptane
• Structural isomers have same formula but different atoms joined differently
• Isomers can have very different properties
pentane
bp 36.2˚C
2-methylbutane
bp 28˚C
2,2-dimethylpropane
bp 9.6˚C
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Functional groups: alkenes
H
H
H
H
ethene
• Ethene - simplest alkene. Very important industrially
• Carbon is trigonal planar - flat and triangular!
• New form of isomerism - configurational isomers
• All atoms bonded in the same manner but different orientation in space
CH3
1-butene
C4H8
H3C
CH3
H3C
2-butenecis-2-butene
trans-2-butene
C4H8
H3C
H3C
2-methylpropene
C4H8
CH3
CH3
CH3
H3C
(1R,5R)-2,6,6-trimethylbicyclo[3.1.1]hept-2-ene
α-pinene
cyclobutane
C4H8
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Functional groups: alkynes & cyclic structures
O
H
OH
H
ethyne
C2H2
O
H3C
pent-3-yn-1-ol
NOT pent-2-yn-5-ol
O
OME
O
O
H3C
• Ethyne is an explosive gas
• Triple bond makes molecular linear (cylinder)
• Examples found in nature (example cleaves DNA)
O
OH
O
MeHN
HO
O
CH3
OH
neocarzinostatin chromophore A
Cycloalkanes and cycloalkenes
cyclopropane
H3C
CH3
1,3-dimethylcyclohexane
cyclohexene
• Cyclic hydrocarbons are common - note that most are not flat
benzene
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Cyclic structures in nature
H3C
CH3
CH3
H
H
CH3
H
H3C
(8R,9S,10S,13R,14S,17R)-10,13-dimethyl-17-(6methylheptan-2-yl)-hexadecahydro-1Hcyclopenta[a]phenanthrene
cholestane - steroid
• Ring systems are common in natural products & pharmaceuticals
• Example below shows the importance of another form of isomerism stereoisomers
CH3
H3C
H
(R)-1-methyl-4-(prop-1-en-2yl)cyclohex-1-ene
(R)-limonene
smells of oranges
CH3
H3C
H
(S)-1-methyl-4-(prop-1-en-2yl)cyclohex-1-ene
(S)-limonene
smells of lemons
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Functional groups: alcohols
H3C
primary
(1°)
CH3
CH3
CH3
H3C
CH3
OH
H
H
(R)-3,7-dimethyloct-6-en-1-ol
citronellol
citronella oil
CH3
CH3
H
H3C
H3C
cholesterol
all animals
• Alcohols contain OH (hydroxy) group
• Found in many natural systems (especially on Friday night)
• Three classes depending on how many C attached to C–OH
• Compounds can have more than one OH (improves water solubility)
HO
HO
OH
1,2-ethandiol
ethylene glycol
antifreeze
HO
HO
OH
CH3
(R)-1-isopropyl-4methylcyclohex-3-enol
terpinen-4-ol
tea tree oil
HO
secondary
(2°)
tertiary
(3°)
O
OH
HO
6-(hydroxymethyl)-tetrahydro2H-pyran-2,3,4,5-tetraol
glucose
sugar I guess!
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Functional groups: phenols and ethers
Phenols
Cl
OH
OH
Cl
Cl
2,4,6-trichlorophenol
TCP
antiseptic
phenol
carbolic acid
• Phenols are distinct from alcohols as attached to phenyl ring - acidic O–H
Ethers
O
O
H3C
O
O
O
O
O
CH3
ethoxyethane
diethyl ether
ether
tetrahydrofuran
THF
O
18-crown-6
• Most commonly used as solvents
• 18-Crown-6 enables metal cations (M+) to dissolve in organic solvents
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Functional groups: alkyl halides and thiols
H
Cl
Cl
Cl
F
Cl
Cl
H
dichloromethane
DCM
Cl
F
Cl
dichlorodifluoromethane
Freon (refrigerant)
a CFC
Cl
Cl
O
H
Cl
dieldrin
H
• Alkyl halides are incredibly useful compounds - used extensively
• Down side is they appear to be bad for us and the environment
Thiols
SH
H2N
H
CO2H
(R)-2-amino-3sulfanylpropanoic acid
cysteine
HS
CH3
H3C
CH3
2-(4-methylcyclohex-3enyl)propane-2-thiol
taste of grapefruit
HS SH
H3C
CH3
propane-2,2-dithiol
HS
H3C
CH3
O
CH3
4-methyl-4sulfanylpentan-2-one
• Thiols are the sulfur analogue of alcohols - and they smell, bad...
• Humans can detect 2x10–5 ppb of the second compound (1 drop in a lake)
• One of the last two compounds is the smelliest known - but no one is
...prepared to make them again to find out which!
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Functional groups: amines
CH3
H3C
O
N
NH2
H2N
OH
H2N H
CH3
triethylamine
smells of fish
(S)-2-amino-3-phenylpropanoic acid
phenylalanine
amino acid
butane-1,4-diamine
putrescine
smells of decay
• Vital in biological systems
• Many smell (bad but not as bad as thiols)
• Found in many compounds that are physiologically active...
N
H
N
CH3 O
CH3
O
N
CH3
(S)-3-(1methylpyrrolidin-2-yl)
pyridine
nicotine
O
O
methyl 3-(benzoyloxy)-8-methyl8-aza-bicyclo[3.2.1]octane-2carboxylate
cocaine
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Functional groups: amines II
H N H
H
ammonia
H3C NH2
methylamine
1° amine
H
N
H3C
CH3
dimethylamine
2° amine
H3C N CH
3
H3C
trimethylamine
3° amine
• Just to confuse, amines are labeled by the number of C attached
• This is different to alcohols (labeled by C attached to C–OH)
secondary
position
(2°)
CH3
O
H3C
primary
amine
(1°)
OH
NH2
valine
H
H3C N CH
3
H3C
trimethylammonium ion
4° ammonium (salt)
If add four groups
everything changes!
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Functional groups: the carbonyl group
• Carbonyl group C=O – analogous to alkene
• Two groups, aldehydes RCHO and ketones R2C=O
Aldehyde
O
O
H
O
H3C
H
methanal
formaldehyde
H
H
ethanal
acetaldehyde
OH
OH
O
HO
OH OH H
(2R,3S,4R,5R)-2,3,4,5,6pentahydroxyhexanal
glucose
benzaldehyde
Ketones
CH3
O
O
H3C
CH3
O
CH3
HO
H3C
propanone
acetone
H
(R)-2-methyl-5-(prop-1-en2-yl)cyclohex-2-enone
(R)-carvone
spearmint
H
H3C
O
CH3
(S)-2-methyl-5-(prop-1-en2-yl)cyclohex-2-enone
(S)-carvone
caraway
4-(4-hydroxyphenyl)
butan-2-one
raspberry ketone
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Functional groups: carboxylic acids & derivatives
H
H
oxidation
R C H
H
hydrocarbon
R C H
OH
alcohol
reduction
H
oxidation
reduction
R C
O
aldehyde
OH
oxidation
reduction
R C
O
carboxylic
acid
• Many of the functional groups are 'linked'
• If we replace one C–H at a time by a C–O we see how these groups relate
O
H3C
H3C CH3
O
HO2C
CO2H
OH
ethanoic acid
acetic acid
vinegar
H3C
OH
OH
maleic acid
CH3
(S)-2-hydroxypropanoic acid
L-(+)-lactic acid
CO2H
O
CH3
(2Z,4E)-3-methyl-5-(2,6,6trimethyl-4-oxocyclohex-2enyl)penta-2,4-dienoic acid
abscisic acid
leaf fall
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Functional groups: derivatives
O
O
+
NaOH
H3C
OH
ethanoic
acid
+
Na
H3C
O
sodium ethanoate
carboxylate ion
sodium
hydroxide
HOH
water
• Reaction of a carboxylic acid with a base (eg. NaOH) gives carboxylate ion
Derivatives
O
H3C
O
O
H3C
O
CH3
ethyl ethanoate
ethyl acetate
solvent
ester
O
CH3
Cl
CH3
NH2
HO2C
H
N
2-methylpropyl propanoate
isobutyl propionate
smell of rum
ester
O
O
aspartame
sweetener
amide
benzoyl chloride
acid chloride
O
OMe
H3C
O
O
CH3
ethanoic anhydride
acetic anhydride
acid anhydride
gjr-–- 21
Classification of functional groups
increasing degree of oxidation
(removal of hydrogen)
• Functional groups can be classed by the degree of oxidation (removal of H)
H
R C H
H
hydrocarbon
alkanes
alcohols
ethers
amines
alkyl
halides
thiols
aldehydes ketones
carboxylic
acids
oxidation
reduction
esters
H
R C H
OH
alcohol
acyl
acid
amides chlorides
anhydrides nitriles
H
oxidation
reduction
R C
O
aldehyde
OH
oxidation
reduction
R C
O
carboxylic
acid
gjr-–- 22
Overview
What have we learnt?
• How to name simple organic molecules
• To recognise common functional groups
• Common examples of these functional groups
What's next?
• To looking at the bonding in molecules in detail
• To understand how bonding effects the shape of molecules
dr gareth rowlands; [email protected]; science tower a4.12
http://www.massey.ac.nz/~gjrowlan