Organic Chemistry

1) Hydrocarbons2) Substituted Hydrocarbons3) Organic Families4) Organic Reactions

Hydrocarbons

• Molecules made of Hydrogen and Carbon• Carbon forms four bonds, hydrogen forms one bond• Hydrocarbons come in three different homologous series:

– Alkanes (single bond between C’s, saturated)– Alkenes (1 double bond between 2 C’s, unsaturated)– Alkynes (1 triple bond between 2 C’s, unsaturated)

• These are called aliphatic, or open-chain, hydrocarbons.• Count the number of carbons and add the appropriate suffix!

Alkanes

• CH4 = methane

• C2H6 = ethane

• C3H8 = propane

• C4H10 = butane

• C5H12 = pentane

• To find the number of hydrogens, double the number of carbons and add 2.

Methane

Meth-: one carbon

-ane: alkane

The simplest organic molecule, also known as natural gas!

Ethane

Eth-: two carbons

-ane: alkane

Propane

Prop-: three carbons

-ane: alkane

Also known as “cylinder gas”, usually stored under pressure and used for gas grills and stoves. It’s also very handy as a fuel for Bunsen burners!

Butane

But-: four carbons

-ane: alkane

Liquefies with moderate pressure, useful for gas lighters. You have probably lit your gas grill with a grill lighter fueled with butane!

Pentane

Pent-: five carbons

-ane: alkane

Your Turn!!!

Draw Hexane:

Draw Heptane:

Alkenes

• C2H4 = Ethene

• C3H6 = Propene

• C4H8 = Butene

• C5H10 = Pentene

• To find the number of hydrogens, double the number of carbons.

EtheneTwo carbons, double bonded. Notice how each carbon has four bonds? Two to the other carbon and two to hydrogen atoms.

Also called “ethylene”, is used for the production of polyethylene, which is an extensively used plastic. Look for the “PE”, “HDPE” (#2 recycling) or “LDPE” (#4 recycling) on your plastic bags and containers!

Propene

Three carbons, two of them double bonded. Notice how each carbon has four bonds?

If you flipped this molecule so that the double bond was on the right side of the molecule instead of the left, it would still be the same molecule. This is true of all alkenes.

Used to make polypropylene (PP, recycling #5), used for dishwasher safe containers and indoor/outdoor carpeting!

ButeneThis is 1-butene, because the double bond is between the 1st and 2nd carbon from the end. The number 1 represents the lowest numbered carbon the double bond is touching.

This is 2-butene. The double bond is between the 2nd and 3rd carbon from the end. Always count from the end the double bond is closest to.

ISOMERS: Molecules that share the same molecular formula, but have different structural formulas.

Pentene

This is 1-pentene. The double bond is on the first carbon from the end.

This is 2-pentene. The double bond is on the second carbon from the end.

This is not another isomer of pentene. This is also 2-pentene, just that the double bond is closer to the right end.

Alkynes

C2H2 = Ethyne C3H4 = Propyne C4H6 = Butyne C5H8 = Pentyne

To find the number of hydrogens, double the number of carbons and subtract 2.

Ethyne

Now, try to draw propyne! Any isomers? Let’s see!

Also known as “acetylene”, used by miners by dripping water on CaC2 to light up mining helmets. The “carbide lamps” were attached to miner’s helmets by a clip and had a large reflective mirror that magnified the acetylene flame.

Used for welding and cutting applications, as ethyne burns at temperatures over 3000oC!

Propyne

This is propyne! Nope! No isomers.

OK, now draw butyne. If there are any isomers, draw them too.

Butyne

Well, here’s 1-butyne!

And here’s 2-butyne!

Is there a 3-butyne? Nope! That would be 1-butyne. With four carbons, the double bond can only be between the 1st and 2nd carbon, or between the 2nd and 3rd carbons.

Now, try pentyne!

Pentyne

1-pentyne

2-pentyne

Now, draw all of the possible isomers for hexyne!

Substituted Hydrocarbons

• Hydrocarbon chains can have three kinds of “dingly-danglies” attached to the chain. If the dingly-dangly is made of anything other than hydrogen and carbon, the molecule ceases to be a hydrocarbon and becomes another type of organic molecule.– Alkyl groups– Halide groups– Other functional groups

• To name a hydrocarbon with an attached group, determine which carbon (use lowest possible number value) the group is attached to. Use di- for 2 groups, tri- for three.

Alkyl Groups

Halide Groups

Organic Families• Each family has a functional group to identify it.

– Alcohol (R-OH, hydroxyl group)– Organic Acid (R-COOH, primary carboxyl group)– Aldehyde (R-CHO, primary carbonyl group)– Ketone (R1-CO-R2, secondary carbonyl group)

– Ether (R1-O-R2)

– Ester (R1-COO-R2, carboxyl group in the middle)

– Amine (R-NH2, amine group)

– Amide (R-CONH2, amide group)• These molecules are alkanes with functional groups attached. The

name is based on the alkane name.

Alcohol

On to DI and TRIHYDROXY ALCOHOLS

Di and Tri-hydroxy Alcohols

Positioning of Functional Group

PRIMARY (1o): the functional group is bonded to a carbon that is on the end of the chain.

SECONDARY (2o): The functional group is bonded to a carbon in the middle of the chain.

TERTIARY (3o): The functional group is bonded to a carbon that is itself directly bonded to three other carbons.

Organic Acid

These are weak acids. The H on the right side is the one that ionized in water to form H3O+. The -COOH (carboxyl) functional group is always on a PRIMARY carbon.

Can be formed from the oxidation of primary alcohols using a KMnO4 catalyst.

Aldehyde

Aldehydes have the CO (carbonyl) groups ALWAYS on a PRIMARY carbon. This is the only structural difference between aldehydes and ketones.

Formed by the oxidation of primary alcohols with a catalyst. Propanal is formed from the oxidation of 1-propanol using pyridinium chlorochromate (PCC) catalyst.*

Ketone

Ketones have the CO (carbonyl) groups ALWAYS on a SECONDARY carbon. This is the only structural difference between ketones and aldehydes.

Can be formed from the dehydration of secondary alcohols with a catalyst. Propanone is formed from the oxidation of 2-propanol using KMnO4 or PCC catalyst.*

Ether

Ethers are made of two alkyl groups surrounding one oxygen atom. The ether is named for the alkyl groups on “ether” side of the oxygen. If a three-carbon alkyl group and a four-carbon alkyl group are on either side, the name would be propyl butyl ether. Made with an etherfication reaction.

Ester

Esters are named for the alcohol and organic acid that reacted by esterification to form the ester. If the alcohol was 1-propanol and the acid was hexanoic acid, the name of the ester would be propyl hexanoate. Esters contain a COO (carboxyl) group in the middle of the molecule, which differentiates them from organic acids.

Amine

- Component of amino acids, and therefore proteins, RNA and DNA…life itself!

- Essentially ammonia (NH3) with the hydrogens replaced by one or more hydrocarbon chains, hence the name “amine”!

Amide

Synthetic Polyamides: nylon, kevlar

Natural Polyamide: silk!

For more information on polymers, go here.

Organic Reactions

• Combustion• Fermentation• Substitution• Addition• Dehydration Synthesis

– Etherification– Esterification

• Saponification• Polymerization

Combustion

• Happens when an organic molecule reacts with oxygen gas to form carbon dioxide and water vapor. Also known as “burning”.

Fermentation

• Process of making ethanol by having yeast digest simple sugars anaerobically. CO2 is a byproduct of this reaction.

• The ethanol produced is toxic and it kills the yeast when the percent by volume of ethanol gets to 14%.

Substitution

• Alkane + Halogen Alkyl Halide + Hydrogen Halide• The halogen atoms substitute for any of the hydrogen atoms in the alkane. This happens one atom at a time. The halide generally replaces an H on the end

of the molecule.

C2H6 + Cl2 C2H5Cl + HCl

The second Cl can then substitute for another H:

C2H5Cl + HCl C2H4Cl2 + H2

Addition

• Alkene + Halogen Alkyl Halide• The double bond is broken, and the halogen adds at either

side of where the double bond was. One isomer possible.

Esterification

• Organic Acid + Alcohol Ester + Water• A dehydrating agent (H2SO4) removes H from the organic acid and removes the OH

from the alcohol. The two molecules join where there H and OH were removed.

Saponification

The process of making soap from glycerol esters (fats).

Glycerol ester + 3 NaOH soap + glycerol

Glyceryl stearate + 3 NaOH sodium stearate + glycerol

The sodium stearate is the soap! It emulsifies grease…surrounds globules with its nonpolar ends, creating micelles with - charge that water can then wash away. Hard water replaces Na+ with Ca+2 and/or other low solubility ions, which forms a precipitate called “soap scum”.

Water softeners remove these hardening ions from your tap water, allowing the soap to dissolve normally.

Polymerization

• A polymer is a very long-chain molecule made up of many monomers (unit molecules) joined together.

• The polymer is named for the monomer that made it.– Polystyrene is made of styrene monomer– Polybutadiene is made of butadiene monomer

• Addition Polymers• Condensation Polymers• Rubber

Addition PolymersJoining monomers together by breaking double bonds

Polyvinyl chloride (PVC): vinyl siding, PVC pipes, etc.

Vinyl chloride polyvinyl chloride

n C2H3Cl -(-C2H3Cl-)-n

Polytetrafluoroethene (PTFE, teflon):

TFE PTFE

n C2F4 -(-C2F4-)-n

Condensation Polymers

Condensation polymerization is just dehydration synthesis, except instead of making one molecule of ether or ester, you make a monster molecule of polyether or polyester.