Transcript Organic Chemistry
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
H 2 O
.
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 sp 3 orbitals, carbon can now form 4 bonds, may be single, or in combination of double (sp 2 ) 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 Hydrocarbons
A. alkanes - comprised of all single bonds
C n H 2n+2
B. alkenes - comprised of at least one double bond
C n H 2n
C. alkynes - comprised of at least one triple bond
C n H 2n-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. CH 3 CH 3
Alkanes
• Hydrocarbon chains where all the bonds between carbons are SINGLE bonds • Name uses the ending – ane • Examples: Meth
ane
, Prop
ane
, But
ane
, Oct
ane
, 2-methylpent
ane
2 3 4 5 1
Prefixes for # of Carbons
Meth 6 Hex Eth Prop But Pent 7 8 Hept Oct 9 Non 10 Dec
Root Meth Eth Prop But Pent Hex Hept Oct Non Dec
Prefix-Parent-SUFFIX
Number of Carbons 1 2 3 4 5 6 7 8 9 10 Functional Group Ending • Alkane • Alkene • Alkyne • Alcohol • Ketone ane ene yne ol one • Aldehyde • Carboxylic acid oic acid • Ester al 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?
2 3 4 5 1
Prefixes for # of Carbons
Meth 6 Hex Eth Prop But Pent 7 8 Hept Oct 9 Non 10 Dec
Endings
• Alkanes (all C-C single bonded parent chain) end in –ane – Meth
ane
CH 4 – Eth
ane
– Prop
ane
C 2 H 6 C 3 H 8 • Attached carbon groups (substituents) end in
–yl
– Meth
yl
CH 3 – Eth
yl
– Prop
yl
CH 3 CH 2 CH 3 CH 2 CH 2 – 3-ethyl pentane
Step 2. Number the parent chain.
• Number the parent chain so that the attached groups are on the lowest numbers Methyl is on carbon #2 of the parent chain Methyl is on carbon #4 of the parent chain 1 2 3 4 5 5 4 3 2 1 GREEN is the right way for this one!
1 1 4 5 6
3
Groups on 4, 6, and 7 Groups on 2, 3, and 5 1 7 2 3 4 5 6 1 7 Groups on 2 and 5 Groups on 3 and 6
Step 3. Name the attached groups.
• Carbon (alk yl ) groups – Meth
yl
CH 3 – Eth
yl
– Prop
yl
CH 3 CH 2 CH 3 CH 2 CH 2 – • 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.
2-methyl 1 2 3 4 5
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 Alkanes
3,3-diethylpentane 2,4-dimethylhexane 2,3,4-trimethylhexane
CH 3 CH(CH 3 ) 2 CH 2 CH 2 Br CH 3 CH 3 C CH 3 CH CH 3 CH CH CH 2 CH 3 CH CH 3
Alkanes
2 3 CH 3 CH 3 CH 3 CHCH 3 C CH 2 CH 2 CH 3 CH 2 Br CH 3 CH 3 CH 3 CH CH 3 CH CH CH 2 C CH 3 CH CH 3 CH 2 CH 3 CH 3
CH 3 CH(CH 3 ) 2 CH 2 CH 2 Br CH 3 CH 3 C CH 3 CH CH 3 CH CH CH 2 CH 3 CH CH 3
Alkanes
2 3 CH 3 CH 3 CH 3 CHCH 3 C CH 2 CH 2 CH 3 CH 2 Br CH 3 CH 3 CH 3 CH CH 3 CH CH CH 2 C CH 3 CH CH 3 CH 2 CH 3 CH 3 1-bromo-3-ethyl-3,4-dimethylpentane 2,2,3,6-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