12.01 organic chemistry - san diego miramar...

Aug ‘171 Organic Chemistry

12.01 Organic Chemistry

Dr. Fred Omega GarcesChemistry 100Miramar College

Chemistry of Carbon

An Introduction to nomenclatures, structures and reactions


What is Organic Chemistry ?

Organic Chemistry: Study of carbon containing compounds.Everything else is considered inorganic.

Over 5 million chemicals known of these200 - 300 thousands are inorganic.

Why are there so many organic compounds?

O CH

HH C C

H

HH

H CH

HC C

O C CB r

H

H

HNH

H

C lC C H

H

HH

O C CB r

C lH

CC

NH

C CH2

C

H2CH

CCC

CC

CC C C( )nF

F

F

F

F

F

F

F

CC C CH

H H

H

H H

CC C HB r

(CH2)8H3CB r

H

F

C l

H

H

CH3

H3C CH3

CH3C CH3

C

OH

HHH

CHOO

NO2CH3

CH3

H

B rCH3

H

H

CH3

B r

B rCO C CH3C C

NH2HO

H

OHC

H

OH

HO

OCH3

COH

O

CH3C CH2OH

H

CH3 CH2 CO

OH

OH

CH3 CH2 C OH

CH C CH3CH3

H2C CH

R CO

CH CH CH3H3CCH3

OH

H2C

H2CO

C

CO O

O

H3CCH3

+ H2

+ HBr


The magic Carbon atom

Difference between organic and inorganic is C-atom ability to form very long chain

Inorganic compound will become unstable after with 12 or more atoms.C-atoms ability to form very strong covalent bond means molecules can possess 100 or more atoms


Evolution of Organic Chemistry

“Can man artificially create a living animal from chemicals ?”

- magnitude of question concerning organic compoundPrior to 1828, organic compounds can only be obtained from living organismFredrick Wohler prepared urea - chemical in urine (an organic compound)

NH4Cl + AgNCO g NH2-CO-NH2 + Ag

Now a days the bulk of organic compoundsis manufactured in the lab.


Source of Organic Compound

Organic chemicals isolate from nature. Nature has her huge laboratory and is constantly synthesizing chemicals through biosynthesis.

Today we can manufacture these same chemicals in the lab

Mescaline

CaffeineTetrahydrocannabinol THC

HO

H

H

HH

H

Ethanol


Lewis Dot Structure :Number of bonds for nonmetal atom

Lewis Dot Structure and VSEPR: revisitedH C N O X

Val. e- 1 4 5 6 7

# Bonds 1 4 3 2 1H-H CH4 NH3 H2O H-Cl


Forms of Carbons

Carbons with single bond :Methane, CH4 Tetrahedral 109.5° sp3

Carbons with double bondsethene, C2H6 Trig. planar 120° sp2

Carbons with triple bondsethyne C2H2 Linear 180° sp

HC CH


Structure - Ways of presenting organic Compounds

Consider: Ethanol and dimethylether C2H6O Molecular formula - indicate type and number of atoms

C2H6O C2H6O Structure formula - shows connectivity of atoms in a compound

Ethanol Dimethylether

Condense formula - shows connecting group of atoms in a compoundEthanol, CH3CH2OH Dimethylether, CH3OCH3

Shorthand notation - shows hydrocarbon as "R" and functional group as is.Ethanol R-OH Dimethylether R-O-R’

Stick form - shows hydrocarbons as lines with functional groupEthanol Dimethylether

Isomers - Compounds that have the same formula but different structuresEthanol and dimethylether have the same formula but are different compounds

and therefore possesses different propertiesEthanol is the drinkable alcohol, while dimethyl ether was used as an anesthetic.

OHO


Organic Compounds; the Family Tree.

Organic Compounds

cyclo Aliphatics

Hydrocarbons Heteroatoms

AromaticAliphatics

Alkane

Alkene

Alkyne

O

CH3CH3

CNH

O


Alkanes CnH2n+2

Hydrocarbons with only single bonds

Methane CH4

Ethane C2H6

Propane C3H8

Butane C4H10

Pentane C5H12

The Alkanes


Degree of Carbon

a) primary carbons, 1° -a) carbons bonded to only one other carbon

b) secondary carbons, 2° -carbons bonded to two other carbons

c) tertiary carbons, 3° -carbons bonded to three other carbons

d) quaternary carbons, 4° -carbons bonded to four other carbons

C

CH2

CH3

CH

CH3

CH3

CH3CH3


Prefix and the Number of Carbons# of

CMolecularFormula

Prefix Alkanename

Structure and isomers

groupname

1 CH4 meth- methane CH4 methyl2 C2H6 eth- ethane ethyl3 C3H8 prop- propane propyl, i-propyl4 C4H10 but- butane

, butyl, iso-butyl

sec-butyl, tert-butyl5 C5H12 pent- pentane

, ,

pentyl

6 C6H14 hex- hexane etc... -

7 C7H16 hept- heptane -8 C8H18 oct- octane -9 C9H20 non- nonane -

10 C10H22 dec- decane -


Isomers are molecules with the same chemical formula but different structural formula.Pentane

n-pentane, iso-pentane, neo-pentane

Hexanen-hexane 2-methylpentane 3-methylpentane

2,4-dimethylbutane 2,2-dimethylbutane

Isomers


Alkyl group (in naming scheme)Alkyl group - An important idea in the naming scheme is the

group of atoms attached to a carbon chain.yl - suffix indicating group

First 5 alkyl groups and their isomers:

1. Methyl 2 . Ethyl

3 .Propyl: n-propyl, isopropyl

4 .Butyl: n-butyl, sec-butyl, iso-butyl, tert-butyl

5. Pentyl: n-pentyl, sec-pentyl, iso-pentyl, neo-butyl

H

HCH

H

H

HH

C

H

HC C

H

H H

HH

HC C

H

H

H H

H

methane g methyl ethane g ethyl

..

. . . .

..


IUPAC NomenclatureRules of the game:Alkane (CnH2n+2)

1. Find the longest continuous chain of carbon atoms. Assign this chain as the parent name .

2. Determine the substituents (groups) attached to the parent chain3. Assign attachment position of group to main chain by starting at end

which gives lowest position number.*4. Identical groups attached to the main chain are designated with

prefixes.2-di, 3-tri, 4-tetra, 5-penta

5. Different groups attached to main chain are written in alphabeticalorder.

6. Alkyl halides: Halogen atoms (group) are designated as halogen prefix.F - Fluoro, Cl-Chloro, Br- Bromo, I- Iodo

7. Alkyl groups (see previous page)

* The numbering scheme should be chosen such that the sum of the position in which group are attached add up to the lowest sum.


• Consider the following hexane compound:Heptane (C7H16)

1. Pentane

2. Methyl

3. Carbon # 2 & # 3

4. 2,3 = position methyl = group pentane = parent name

5. Two methyl g dimethyl

6. Name: 2,3-dimethylpentane

IUPAC nomenclature, an example


Functional GroupName -Suffix group Example

1 Aliphatics -ane, -ene,-yen

, , , , propane, propene, proyne

2 Alcohol -ol =

propanol3 Ether - ether ,

ethylpropylether4 Aldehydes -al

, propanal

5 Ketones -one

, propanone

6 Carboxylicacid

-oic acid,

propanoic acid7 Ester -ate

, methyl propanoate

8 amine -amine

, triethyl amine

9 amide -amide,

N-methylpropamide

C C C C C C

OHOH

R O R ' O

R C OH C O

H

R CO

R 'CO

R CO

OH CO

OH

R CO

O R 'CO

O

R NR '

R ' N

NR '

R 'RC

ONHC

O


Alkenes CnH2n • Alkynes CnH2n-2

Hydrocarbons with multiple bonds- Ethene, C2H4 - Ethyne,C2H2

- Propene, C3H6 - Propyne, C3H4

Note: If there is more than one multiple bond _ poly unsaturatedi.e.,

Alkenes and Alkynes


More on AlkenesGeometric Isomers

Cis 2-butene Trans 2-butene

Can’t rotate the double bond which makes these molecules unique compounds or Geometric isomers.Life example: 11-cis-retinal g all trans retinal

R

C

O

H

RH

Ohn

dark with enzyme Signals optic

nerve cellVisual pigment

(rhodopsin)


more rules of the game:

Alkene (CnH2n) -ene (suffix)1. - ene suffix for alkenes 2. Main chain must include the double bond.3. position of double bond indicated by prefix numbering location.4. For multiple double bonds :

di = 2 double bondstri = 3 double bonds

Alkyne (CnH2n-2) -yne (suffix)1. - yne suffix for alkynes2. Nomenclature rules are similar to that

of alkenes

Nomenclature: Alkenes and Alkyne

2-propyl-1-pentene

2-methyl-1,3,5-heptatriene

3-ethyl-4-methyl-1-hexyne


Aromatics: nomenclature1. Monosubstituted

a. group benzene

b. special name

2. Two substituted groups - use prefix for position

3. Three substituted groups- requires # scheme (lowest position scheme)

4. Benzene as a group- phenyl

NO2 Cl Br CH2CH3

OH CH3 NH2 CO

OH

Xo (ortho)

m(meta)p(para)

X1

2

34

5


Summary

12.01 organic chemistry - san diego miramar...

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