Unit 31 - Organic Functional Groups and Introduction to 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 Name Chemical Representation Functional Group Name Chemical Representation halogen R-X, where X is a member of Group 17 ketone O R-C-R’ alcohol R-OH carboxylic acid O R-C-OH ether R-O-R’ ester O R-C-OR’ aldehyde O R-C-H Note: R and R’ refer to other carbon-hydrogen groups such as a methyl (-CH 3 ), ethyl (-C 2 H 5 ), etc. or even larger groups. The R’ only indicates it doesn’t have to be the same as R. Also note the group C=O that shows up commonly above is called a carbonyl group.

Some common examples Perhaps 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. Let’s look at examples of families identified by functional groups

Famous examples methanol ethanol isopropanol or isopropyl alcohol Alcohols: (red spheres are oxygen) All alcohols are toxic at some level. Methanol (also known as wood alcohol) can cause blindness and even death at very low doses. Ethanol is the “social” alcohol – that in beer 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 of antifreeze. It is also highly toxic. Notice that is has two -OH groups. ethylene glycol

Ethers and Aldehydes ethyl ether Ethers: The compound to the right is diethyl ether or more commonly just called ether. Ether used to be used as an anesthetic but is now more commonly used as a solvent for organic compounds. formaldehyde Aldehydes: The aldehyde to the right is called formaldehyde. Its water solution (formalin) is commonly used in preserving biological specimens and in embalming fluid.

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

Esters Esters: Though not a famous ester, the methyl butyrate to the right is a compound that smells like apples. Many of the esters have a fruity smell to them and actually give fruit its characteristic 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. A B C D

An Introduction to Polymers Polymers 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 Polymerization Addition Rubber Condensation polymers

Addition Polymerization -Nothing given up in addition -Examples: polyethylene, polypropylene, Teflon, PVC, Plexiglas, Saran Wrap

Condensation Polymerization + -Small molecule – usually water, ammonia, methanol, or HCl – is ejected -Examples: nylon, polyethylene terephthalate (PET), polycarbonates, polyurethanes,

Recycling Symbols

End of Slide Show