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Unit 31 -Organic Functional Groupsand Introductionto Polymers

You should read Sections 9.3 9.8 and Sections 10.3 10.5 prior to reviewing these slides.

Functional Groups (9.4)Though what you have seen so far can account a limitless number of organic compounds, the possibilities are even greater.

Consider that each of the hydrogen atoms in the previous compounds could be replaced by something else another carbon, a halogen, an oxygen, a nitrogen, and so on and so on.

This leads to the concept of functional groups for organic compounds atoms or groups of atoms that give a set of organic compounds its characteristic physical and chemical properties.

We will look at just a few functional groups: halogens, alcohols, ethers, aldehydes, ketones, carboxylic acids and esters

Functional Groups (continued)Functional Group NameChemical RepresentationFunctional Group NameChemical RepresentationhalogenR-X, where X is a member of Group 17ketone O

R-C-RalcoholR-OHcarboxylic acid

O

R-C-OHetherR-O-Rester

O

R-C-ORaldehyde O

R-C-HNote: R and R refer to other carbon-hydrogen groups such as a methyl (-CH3), ethyl (-C2H5), etc. or even larger groups. The R only indicates it doesnt have to be the same as R.Also note the group C=O that shows up commonly above is called a carbonyl group.

4Some common examplesPerhaps one way of wrapping up this part of the presentation on functional groups is to give some examples of organic compounds you may run into in everyday life.Lets look at examples of families identified by functional groups

Famous examples

methanol ethanol isopropanol or isopropyl alcoholAlcohols: (red spheres are oxygen)All alcohols are toxic at some level.Methanol (also known as wood alcohol) can cause blindness andeven death at very low doses. Ethanol is the social alcohol that inbeer and wine and mixed drinks. But even that is toxic at high enough levels. Isopropyl alcohol is the one you buy as rubbing alcohol.

Ethylene glycol to the right is the major component ofantifreeze. It is also highly toxic. Notice that is has two-OH groups.

ethylene glycol

Ethers and Aldehydes

ethyl etherEthers: The compound to the right is diethyl etheror more commonly just called ether. Ether used tobe used as an anesthetic but is now more commonlyused as a solvent for organic compounds.

formaldehydeAldehydes: The aldehyde to the right is calledformaldehyde. Its water solution (formalin) is commonly used in preserving biological specimens and in embalming fluid.

Ketones and Carboxylic AcidsKetones: Acetone and methyl ethyl ketone,illustrated on the right, are commonly used in fingernail polish remover. Carboxylic Acids: Acetic acid, on the right, isrequired by law to be around the 5% level in vinegar. Acids typically give that sour taste.

acetone methyl ethyl ketoneacetic acid

Esters

Esters: Though not a famous ester,the methyl butyrate to the right is acompound that smells like apples.

Many of the esters have a fruity smellto them and actually give fruit itscharacteristic smell. Esters are formed from alcohols and fairly typically bad smelling carboxylic acids. When the fruity ester breaks down, you are left with the bad smelling carboxylic acid aroma you associate with rotten fruit.

Saturated, Unsaturated and Trans Fats

You have probably heard the discussion about saturated fats, unsaturated fats, and trans fats. The figures to the right show the differences. Notice all of the fats are carboxylic acids they have that COOH group.

The terms saturated and unsaturated come directly from whether or not the fat is all single C-C bonds (A) or contains some double C=C bonds (B and C).

The term trans- refers to the orientation around the double bond (D). In the trans- configuration, the hydrogens on the C=C double bonds are on opposite sides of the chain. In the cis- configuration, they are on the same side.ABCD

An Introduction to PolymersPolymers are very large molecules formed by the reaction of smaller units called monomers

Polymers are both natural (DNA, RNA, starches, proteins, cellulose, etc.) and synthetic (polyethylene, polypropylene, celluloid) by far there are more naturally occurring polymers than synthetic

Types of PolymerizationAddition

Rubber

Condensation polymers

Addition PolymerizationNothing given up in additionExamples: polyethylene, polypropylene, Teflon, PVC, Plexiglas, Saran Wrap

Condensation Polymerization

+Small molecule usually water, ammonia, methanol, or HCl is ejectedExamples: nylon, polyethylene terephthalate (PET), polycarbonates, polyurethanes,

Recycling Symbols

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