Last lecture...

1

Last lecture...

•

Organic chemistry is wonderful!

•

How to represent molecules

•

Abbreviations frequently used for clarity

O

O O

O

zocor ($5.6 billion)

(1S,3R,7S,8S,8aR)-3,7,8a-trimethyl-8- (2-((2R,4R)-4-methyl-6-oxo-tetrahydro-

2H-pyran-2-yl)ethyl)-1,2,3,7,8,8a- hexahydronaphthalen-1-yl 2,2-

dimethylbutanoate

2

Naming organic compounds

•

Identify longest chain (or ring) and name as 'alkane'

•

Identify major functional group; replace '-ane' with suffix

•

Number atoms in chain; begin near functional group

•

Identify substituents & number; name and position is prefix. Order alphabetically. Use 'di' & 'tri' if more than one of the same group

Prefix Parent Suffix

length of main carbon chain substituents / minor functional

groups & their position

major functional group

number of

carbons name number of

carbons name

1 methane 6 hexane

2 ethane 7 heptane

3 propane 8 octane

4 butane 9 nonane

5 pentane 10 decane

= cyclopropane

= cyclodecane

3

Naming organic compounds II

major functional

group suffix major functional

group suffix

alkene -ene aldehyde -anal

alkyne -yne ketone -anone

alcohol -anol carboxylic acid -anoic acid

amine -ylamine acid chloride -anoyl chloride nitrile -anenitrile

minor functional

group prefix minor functional

group prefix

choride chloro- aldehyde formyl-

bromide bromo- ketone oxo-

iodide iodo- nitro nitro-

alcohol hydroxy- amine amino-

ether alkoxy- nitrile cyano-

functional group priorities carboxylic acid > acid chloride >

aldehyde > nitrile > ketone > alcohol >

amine > halide

Systematic organic nomenclature is dull and takes up several volumes.

But it is useful as it unambiguously defines a structure and allows us to easily communicate (if we can

pronounce the entire name) chemical ideas

4

Names: Alkanes

•

Alkanes are dull & unreactive. You can burn them or (&

this is what we do) use them as solvents for reactions.

Numbering should use the lowest values possible.

•

Different branch points are named as above and can greatly influence the chemistry of the functional groups (Z) at these positions.

H Z

Z H

H

primary Z secondary

tertiary 2,3-dimethylpentane

NOT 3,4-dimethylpentane

4-ethyl-2-methylhexane

Cl

4-chloro-2-ethyl-1- methylcyclohexane

5

Names: Alkenes

Very useful functional group. Also found extensively in nature

H

H H

H

ethene hex-2-ene

NOT hex-4-ene E-hex-2-ene or trans-hex-2-ene

Z-hex-2-ene or cis-hex-2-ene

(1R,5R)-2,6,6-

trimethylbicyclo[3.1.1]hept-2-ene α-pinene

(S)-1-methyl-4-(prop-1-en- 2-yl)cyclohex-1-ene

limonene

OMe O

E

Ph Ph

Z

MeO Ph

Ph

E

Highest priority given to highest atomic number

6

Names: Alkenes & alkynes

Alkynes are rarer than alkenes but are found in a family of anti-

carcinogens that can cleave DNA Examples

trans-5,5-dimethylhex-2-ene NOT trans-2,2-dimethylhex-4-ene

OH

4-methylpent-3-en-2-ol NOT 2-methylpent-2-en-4-ol

4-methylcyclohexene NOT methylcyclohex-3-ene

O O O O

O O

OH OMe

O

O OH HO

MeHN

neocarzinostatin chromophore A

H propyne

OH

pent-3-yn-1-ol hex-1-en-4-yne NOT hex-5-en-2-yne

7

Names: Alcohols R-OH

Alcohols are an important functional group (obviously!).

Found extensively in nature as they are an effective means to make compounds water soluble. Their position (primary, secondary or tertiary) controls chemistry.

OH

ethanol

OH

2-methylbutan-2-ol

tertiary alcohol OH

2-methylcyclohex-2-en-1-ol NOT 2-methylcyclohex-1-en-3-ol

secondary alcohol primary

alcohol

O O O

HO

OH HO

OH HO

OH OH OH

sucrose

(2R,3R,4S,5R,6R)-2-((2S,3S,4S,5R)-3,4-dihydroxy- 2,5-bis(hydroxymethyl)-tetrahydrofuran-2-yloxy)-6-

(hydroxymethyl)-tetrahydro-2H-pyran-3,4,5-triol

8

Ethers R-O-R' & alkyl halides R-X

Ethers are common solvents and hence, just to annoy you, chemists use 'nick-names' and abbreviations instead of their systematic names.

O

ethoxyethane diethyl ether

ether

O

2-methoxy-2-methylpropane methyl tert-butyl ether

MTBE

tetrahydrofuranO THF

R X

wild card X = F, Cl, Br, I

Cl

Br

1-chloro-2-methylpropane primary halide

(1-bromoethyl)benzene secondary halide

Incredibly useful reagents. All very similar with alkyl iodides being the most reactive and alkyl fluorides the least reactive.

9

Names: Amines

Amines are incredibly important biologically. Unfortunately, they tend to smell bad (understatement). They can cause confusion with the definitions of primary, secondary &

tertiary...

H₂N

NH₂

putrescine butane-1,4-diamine

NH₂

amphetamine

1-phenylpropan-2-amine HO

NH₂

OH O

serine (S)-2-amino-3- hydroxypropanoic acid

NH₂

ethylamine primary amine

NH₂

isopropylamine 2-aminopropane

primary amine

NH

diethylamine secondary amine

N

triethylamine tertiary amine secondary

position

10

Names: Carbonyl group

O H pentenal an aldehyde

O

propanone (acetone)

a ketone H

O

ethanal (acetaldehyde)

HO

O

4-(4-hydroxyphenyl)butan-2-one raspberry ketone

OH O

ethanoic acid (acetic acid)

O OH

benzoic acid

Carboxylic acids

O O

ethyl ethanoate (ethyl acetate)

O O

3-methylbutyl ethanoate (isopentyl acetate)

bananas

O O

2-methylpropyl propanoate (isobutyl propionate)

rum

Esters

11

Names: Amides & acyl chlorides

•

Like amines, amides can be primary, secondary or tertiary

NH₂ O

ethanamide primary amide

NH Ph O

N-phenylpropanamide secondary amide

H N

O

dimethylformamide (DMF)

(N,N-dimethylmethanamide) tertiary amide

HO₂C H

N OMe

O

O NH₂

aspartame (a peptide)

HO

HN

O paracetamol

Cl O

Cl O

ethanoyl chloride benzoyl chloride

12

Trivial names

Some compounds are only really known by their trivial names

ether diethyl ether

O

acetone

formic acid acetic acid

AcOH

benzene

PhH ethyl acetate EtOAc

toluene

pyridine

pyr phenol

THF

tetrahydrofuran O HO

H

O

O N

HO

O H N

O

DMF

N,N-dimethylformamide

S O

DMSO

(methylsulfinyl)methane Dimethyl sulfoxide O

OH O