organic chemistry last unit for the year.. what does organic mean? the word organic – –in...

Organic Chemistry

Last unit for the year.

What does Organic mean?

• The word Organic –– in Biology it means any thing that is living or

has lived. The opposite is Non-Organic. – in Chemistry, an Organic compound is one

containing Carbon atoms. The opposite term is Inorganic.

Inorganic

• All substances are made up of molecules which are collections of atoms.

• We have spent the year studying simple Inorganic molecules containing only a few atoms.

– For example, a water molecule is composed of two atoms of Hydrogen and one atom of Oxygen. We write its formula as H2O. 

Carbon

• By far and away the best atom for making large molecules with is Carbon.

• Carbon can make molecules that have tens, hundreds, thousands even millions of atoms!

• The huge number of possible combinations means that there are more Carbon compounds than those of all the other elements put together!

• A single Carbon atom is capable of combining with up to four other atoms.

• The Carbon atom is one of the few that will combine with itself.

• This means that Carbon atoms can form chains and rings onto which other atoms can be attached.

• This leads to a huge number of different compounds. All organic chemistry is based upon unique properties of the carbon atom.

Carbon Atom

• Carbon, C, hybridization to 3 sp3 orbitals, carbon can now form 4 bonds, may be single, or in combination of double (sp2) or triple bonds (sp). Carbon forms very strong bonds with many non-metal atoms, H, O, Cl, N. – Note: silicon and germanium are in the same

family and form 4 bonds, but the bond energy is low, so weak bonds are formed. This severely restricts their chemistry.

Hydrocarbons

• Carbon compounds are classified according to how the Carbon atoms are arranged and what other groups of atoms are attached.

• The simplest Organic compounds are made up of only Carbon and Hydrogen atoms only. Even these run into thousands!

• Compounds of Carbon and Hydrogen only are called Hydrocarbons.

• Saturated Hydrocarbon - only C-H and single C-C

• Unsaturated Hydrocarbon - one or more multiple C-C   

1. Straight chain: The carbons are bonded to no more than two other carbons.

2. Branched chain: At least one carbon is bonded to more than two other carbons. The branches are referred to as substituent groups.

3. Cyclic: All of the carbons are bonded to two other carbons. Aromatic compounds are a special class

of cyclic hydrocarbons.

Types of HydrocarbonsA. alkanes - comprised of all single bonds

CnH2n+2

B. alkenes - comprised of at least one double bond CnH2n

C. alkynes - comprised of at least one triple bond CnH2n-2

Structural vs Condensed

Structural formulas show all the atoms and bonds in the molecule.

Condensed structural formulas show the number of hydrogens around each carbon. CH3CH3

Alkanes

• Hydrocarbon chains where all the bonds between carbons are SINGLE bonds

• Name uses the ending –ane• Examples: Methane, Propane, Butane,

Octane, 2-methylpentane

Prefixes for # of Carbons

1 Meth 6 Hex

2 Eth 7 Hept

3 Prop 8 Oct

4 But 9 Non

5 Pent 10 Dec

Prefix-Parent-SUFFIX

Root Number of CarbonsMeth 1Eth 2Prop 3But 4Pent 5Hex 6Hept 7Oct 8Non 9Dec 10

Functional Group Ending• Alkane ane• Alkene ene• Alkyne yne• Alcohol ol• Ketone one• Aldehyde al• Carboxylic acid oic acid• Ester oate• Amide amide

Summary: IUPAC Rules for Alkane Nomenclature

 1.   Find and name the longest continuous carbon chain. This is called the parent chain. (Examples: methane, propane, etc.)

 2.   Number the chain consecutively, starting at the end nearest an attached group (substituent).

 3.   Identify and name groups attached to this chain. (Examples: methyl-, bromo-, etc.)

 4.   Designate the location of each substituent group with the number of the carbon parent chain on which the group is attached. Place a dash between numbers and letters. The prefixes di-, tri-, etc. are used to indicate multiple identical substituents. (Example: 3-chloropentane)

 5.   Assemble the name, listing groups in alphabetical order.     The prefixes di, tri, tetra etc., used to designate several groups of the same kind, are not considered when alphabetizing. Place a comma between multiple numbers. (Example: 2,3-dichloropropane)

Step 1. Find the parent chain.

• Where is the longest continuous chain of carbons?

Prefixes for # of Carbons

1 Meth 6 Hex

2 Eth 7 Hept

3 Prop 8 Oct

4 But 9 Non

5 Pent 10 Dec

Endings

• Alkanes (all C-C single bonded parent chain) end in –ane– Methane CH4

– Ethane C2H6

– Propane C3H8

• Attached carbon groups (substituents) end in –yl– Methyl CH3 -– Ethyl CH3CH2-– Propyl CH3CH2CH2 –     

3-ethylpentane

Step 2. Number the parent chain.

• Number the parent chain so that the attached groups are on the lowest numbers

1 2 3 4 5

Methyl is on carbon #2 of the parent chain

5 4 3 2 1

Methyl is on carbon #4 of the parent chain

GREEN is the right way for this one!

1 2

3 7 8

4 5 6

8 7

6 2 1

5 4 3

Groups on 2, 3, and 5

Groups on 4, 6, and 7

1 2 3 4 5 6

7

Groups on 2 and 5

7 6 5 4 3 2 1

Groups on 3 and 6

Step 3. Name the attached groups.

• Carbon (alkyl) groups– Methyl CH3 -– Ethyl CH3CH2-– Propyl CH3CH2CH2 –

• Halogens– Fluoro (F-)– Chloro (Cl-)– Bromo (Br-)– Iodo (I-)

Step 4. Designate where the group is attached to the parent chain.

• Use the numbers of the parent chain from step 2 to designate the location of the attached groups to the parent chain.

1 2 3 4 5

2-methyl

Step 5. Alphabetize the groups, combine like groups, and assemble.

• The prefixes di, tri, tetra etc., used to designate several groups of the same kind

• Prefixes are not considered when alphabetizing (Example: dimethyl = m for alphabetizing)

• Parent chain goes LAST

1,1,1-trichloro-1-fluoromethane

1,1-dichloro-1,1-difluoromethane

Name the Alkanes

Name the Alkanes2,4-dimethylhexane

3,3-diethylpentane

2,3,4-trimethylhexane

Alkanes

Example: Name the following compounds:

CH3

CH3CH(CH

3)2CH

2CH

2Br

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

C CH2 CH

2Br

CHCH3

CH2CH

3

CH3

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

Alkanes

Example: Name the following compounds:

CH3

CH3CH(CH

3)2CH

2CH

2Br

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

C CH2 CH

2Br

CHCH3

CH2CH

3

CH3

CH3

CH CH CH2

CH CH3

CH2CH

3C

CH

CH3

CH3

CH3

CH3

CH3

1-bromo-3-ethyl-3,4-dimethylpentane2,2,3,6-tetramethyl-4-isopropyloctane

Draw Some Simple Alkanes

• 2-methylpentane

• 3-ethylhexane

• 2,2-dimethylbutane

• 2,3-dimethylbutane

Alkanes

Example: Write the condensed structure for the following compounds:

3,3-dimethylpentane

1,2-dichloro-3-methylheptane

On packet

• Number 9 – tert-, sec-, n-butyl