ORGANIC CHEMISTRY

The chemistry of carbon compounds ORGANIC—CHEMISTRY The chemistry of carbon compounds

Hydrocarbons

Hydrocarbons … are the simplest organic molecules … containing only hydrogen and carbon. The names of the hydrocarbons are used in the naming system of the other organic compounds.

Methane, ethane, propane, butane…

Methane, ethane, propane, butane… Repeat it with me: Methane, ethane, propane, butane… Methane, ethane, propane, butane…

Methane, ethane, propane, butane… Methane: CH4 Ethane C2H6 Propane C3H8 Butane C4H10 All have the formula:

Methane, ethane, propane, butane… Methane: CH4 Ethane C2H6 Propane C3H8 Butane C4H10 All have the formula: CxH2x+2

Methane, ethane, propane, butane… Methane: CH4 Ethane C2H6 Propane C3H8 Butane C4H10 All have the formula: Pentane: C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18 (and so on…) CxH2x+2

Lewis diagrams H H H H C H H C C H H H H H H H H H H H H C C C H H C C Methane, ethane, propane, butane… H H H H H H H H C C C H H C C C C H H H H H H H H

What is the difference? H H H H H C C C C H H H H H H H H H C C C H H

Here’s a hint– it’s not the formula! What is the difference? H H H H C4H10 H C C C C H Here’s a hint– it’s not the formula! H H H H H H H C4H10 H C C C H H H H C H H

These are structural isomers Butane H C C C C H Different chemical and physical properties H H H H H H H H C C C H H H H C H Methylpropane H

The longest chain has branches Substituted alkanes Still have CxH2x+2 No rings or double bonds But!—not a single chain. The longest chain has branches

What is the longest chain?

What is the longest chain?

Now is a very good time… …to shift to the carbon skeleton diagrams.

Lewis diagrams H H H H H H H H C C C H H C C C C H H H H H H H H Propane Butane H H H H H H H H C C C H H C C C C H H H H H H H H

Carbon skeleton diagrams Propane Butane The bars represent the C-C bonds. H are not shown

Carbon skeleton diagrams Propane Butane 2 2 4 3 1 3 1 Count your carbons carefully!

What molecule is shown?

What molecule is shown? Hexane Pentane Butane Heptane

Naming substituted alkanes

Naming substituted alkanes 3-methylhexane 2-methylhexane Heptane 3-methylhexane (again!)

Rules: Find the longest chain, name it Branches are named by their length, using a –yl ending to show they are attached Methyl, ethyl, propyl, butyl… Show where the branches come from using carbon numbers before the branch name Start from the end to minimize the numbers Multiple branches use di, tri, tetra,…prefixes Alphabetize the branches

For example

For example Longest chain=8 carbons, octane

Or… Longest chain=8 carbons, octane

For example 2 methyl groups, on the 4th and 5th carbons

For example Ethyl group, on the 3rd carbon (not the 6th!-number from the end that minimizes the total)

3-ethyl-4,5-dimethyloctane For example Which gives us: 3-ethyl-4,5-dimethyloctane

Name these molecules 1) 2) 3) 4)

Functional groups: Double bonds (-C=C-) Make alkenes End in –ene CxH2x 1-butene 2-butene

Functional groups: Triple bonds (-C≡C-) Make alkynes End in –yne CxH2x-2 1-butyne 2-butyne

Name these molecules 1) 2) 3) 4)

Functional groups: Hydroxyl groups (-O-H) Make alcohols End in –ol CxH2x+1OH 1-butanol 2-butanol OH OH

Functional groups: Terminal carbonyls (-CHO) Make aldehydes End in –al CxH2xO butanal propanal O O

Functional groups: Internal carbonyls (-C=O) Make ketones End in –one CxH2xO 2-pentanone 3-pentanone O O

Name these molecules O 1) 2) 3) 4) HO O OH

Functional groups: Ether linkages (-C-O-C-) Make ethers End in “ether” CxH2x+2O ethylmethyl ether ethylpropyl ether O O

Functional groups: Ester linkages (-C-O-C=O) Make esters End in “-oate” CxH2xO2 ethylmethanoate propylethanoate O O O O

Functional groups: Carboxyl groups (-COOH) Make organic acids End in “-oic acid” CxH2xO2 ethanoic acid propanoic acid O O HO OH

Functional groups: Amino groups (-C-NH2) Make amines End in “-amine” CxH2x+1NH2 2-pentamine 1-butamine NH2 NH2

Functional groups: Halides ( -X where X=Cl, F, Br, I) Make organic halides Named as a branched alkane CxH2x+1X 2-chloropentane 1,1-dibromobutane Br Cl Br

Functional groups: Rings Make cycloalkanes Named with prefix “cyclo-” CxH2x cyclopentane methylcyclobutane

Functional groups: The benzene ring Make substituted benzene or phenylalkanes Named as “–benzene” or a branch “phenyl-” C6H6—has 3 double bonds! benzene

Methylbenzene Hydroxybenzene Aminobenzene Benzoic acid NH2 OH COOH Usually called: (Once known as: toluene phenol aniline carbolic acid)

Ortho-, meta-, para. Meta-dichlorobenzene Cl Cl Cl Cl Cl Ortho-dichlorobenzene Cl Para-dichlorobenzene

Draw and name all of the isomers of C5H10

Chirality—”handedness” Draw a Lewis diagram of 2-chloro-2-butanol

Chirality—”handedness” OH H H H H H C C C C H H C H H H H H Cl H H C C C OH H H Cl There really is a difference—these are mirror-image molecules.

Chirality—”handedness” OH H H H H H C C C C H H C H H H H H Cl H H C C C OH H H Cl Any time you find four different groups attached to one (chiral) carbon there are two optical isomers (L and D) of the molecule

Geometric Isomers Alkenes may have both a cis- and a trans- isomer Cis-2-butene (two methyl groups are on the same side) Trans-2-butene (two methyl groups are on opposite sides)

Reactions You will be responsible for: Oxidation Addition Esterification and Polymerization reactions

Oxidation Combustion: CxHyOz + O2CO2 + H2O More gentle oxidations: (use MnO4-, CrO4-2 and others) Primary alcoholsaldehydesacids Secondary alcoholsketones

Addition X YX + Y YX can be H2O, HCl, Hl, HF, HBr , F2, H2, Br2, Cl2, H2SO4, HNO3 and others

Sometimes you get a mixture of products Addition HCl + Cl 2-chloroheptane AND Cl 3-chloroheptane Sometimes you get a mixture of products

Sometimes you don’t X HX + X HX + Markovnikov’s Rule: When adding HX, the H joins the carbon with more H to start with.

Esterification An acid and an alcohol make an ester by dehydration synthesis. O + HO OH O O + H2O

Esterification Propanic acid and ethanol form ethyl propanoate O + HO The acid keeps the carbonyl, so it takes the –oate ending

Polymerization There are two ways to form polymers (repeating chains of monomers) Addition B) Dehydration

Polymerization There are two ways to form polymers (repeating chains of monomers) Addition—a p bond forms a s bond to the next monomer B) Dehydration—a dehydration synthesis occurs to the next monomer

Polymerization There are two ways to form polymers (repeating chains of monomers) Addition—a p bond forms a s bond to the next monomer —requires a double bond B) Dehydration—a dehydration synthesis occurs to the next monomer —requires hydroxyl groups at each end of monomer

Addition polymerization +

Dehydration polymerization HO OH + HO OH O O O O O O O + H2O (can be double acids, amino acids, alternating monomers, etc.)