-Nomenclature (naming) of Alkenes -Addition Polymers -Alkynes -Aromatic Hydrocarbons

1. Alkenes and Alkynes Chapter 3 -Nomenclature (naming) of Alkenes -Addition Polymers -Alkynes -Aromatic Hydrocarbons

2. Alkenes and Alkynes • Unsaturated • contain carbon-carbon double and triple bond to which more hydrogen atoms can be added. • Alkenes: carbon-carbon double bonds • Alkynes: carbon-carbon triple bonds.

3. Alkenes and Alkynes • Alkenes are hydrocarbons with at least one double carbon to carbon bond. • To show the presence of the double bond, the –ane suffix from the alkane name is changed to –ene. • The alkenes are unsaturated with respect to hydrogen • This means it does not have the maximum number of hydrogen atoms as it would if it were an alkane (a saturated hydrocarbon).

4. Alkenes can also add to each other in an addition reaction to form long chains of carbon compounds. • this is called polymerization • The atom or group of atoms that are added to the hydrocarbon are called functional groups. • Functional groups usually have multiple bonds or lone pairs of electrons that make them very reactive.

5. Nomenclature of Alkenes -"ene" used for double bond -double bond must have lowest possible number -branching rules same as alkanes -longest chain must include double bond

6. Naming is similar to naming alkanes except: • The longest continuous chain must contain the double bond. • The base name now ends in –ene. • The carbons are numbered so as to keep the number for the double bond as low as possible. • The base name is given a number which identifies the location of the double bond. • An alkyne is a hydrocarbon with at least one carbon to carbon triple bond. • Naming an alkyne is similar to the alkenes, except the base name ends in –yne.

7. Naming Alkenes and Alkynes • IUPAC nomenclature rules for alkenes and alkynes are similar to alkanes. • Step 1. Name the parent compound. Find the longest chain containing the double or triple bond, and name the parent compound by adding the suffix –ene or –yne to the name of the main chain.

8. Step 2: Number the carbon atoms in the parent chain, beginning at the end nearest to the double or triple bond. If the multiple bond is an equal distance from both ends, begin numbering at the end nearer the first branch point. The number indicates which carbon the multiple bond is AFTER. (i.e. between 2 and 3 is 2-) • Step 3: Assign numbers and names to the branching substituents, and list the substituents alphabetically. Use commas to separate numbers, and hyphens to separate words from numbers.

9. Step 4. Indicate the position of the multiple-bond carbon. If more than one multiple bond is present, identify the position of each multiple bond and use the appropriate ending diene, triene, tetraene, and so forth. • Step 5. Assemble the name.

10. Naming Alkenes and Alkynes When the carbon chain has 4 or more C atoms, number the chain to give the lowest number to the double or triple bond. 1 2 3 4 CH2=CHCH2CH3 1-butene but-1-ene CH3CH=CHCH3 2-butene but-2-ene CH3CCCH3 2-butyne but-2-yne

11. Assigning Priority • Alkenes and alkynes are considered to have equal priority • In a molecule with both a double and a triple bond, whichever is closer to the end of the chain determines the direction of numbering. • In the case where each would have the same position number, the double bond takes the lower number. • In the name, “ene” comes before “yne” because of alphabetization.

12. Learning Check Write the IUPAC name for each of the following unsaturated compounds: A. CH3CH2CCCH3 CH3 B. CH3C=CHCH3 C.

13. Alkenes

14. Alkenes • CH2=CH-CH2-CH3 1-Butene • CH3-CH=CH-CH3 2-Butene • CH2=C-CH3 | CH3 2-methyl Propene

15. Multiple Double/Triple Bonds

16. Cis-Trans Isomerism • Methane is tetrahedral, ethylene is planar, and acetylene is linear as predicted by the VSEPR theory discussed earlier.

17. Cis and Trans Isomers • Double bond is fixed • Cis/trans Isomers are possible CH3 CH3 CH3 CH = CH CH = CH cis trans CH3

18. Cis- and Trans- terminology If alkenes have two different substituents at each end of the C=C then they can exist as stereoisomers because there is restricted rotation of the double bond.For example: • all terminal alkenes (begin or end with a C=CH2) do not exist as cis- and trans- isomers. • all 1,1-symmetrically disubstituted alkenes (has a C=CR2 unit) do not exist as cis- and trans-. • alkenes with the R-CH=CH-R unit can exist as cis- and trans- isomers.

19. In cis isomers, two methyl groups are close together on the same side of the double bond.

20. In trans isomer, two methyl groups are far apart on opposite side of the double bond. • Both cis and trans isomers have the same formula and connections between the atoms but have different three dimensional structures because the way the groups are attached to the carbons.

21. Cis-trans isomerism occurs in an alkene whenever each double bond carbon is bonded to two different substituent groups. Cis-trans isomerism is not possible if one of the double bond carbons is attached to two identical groups.

22. Alkene Examples • Naming Alkenes website

23. ALKYNES - Naming same as alkenes except use "yne" suffix -see examples below

24. Ethylene is the gas that ripens fruit, and a ripe fruit emits the gas, which will act on unripe fruit. Thus, a ripe tomato placed in a sealed bag with green tomatoes will help ripen them.

25. Polymer's - long chain of repeating units is called the POLYMER -simple compound being repeated called MONOMER -common type called Addition Polymers since created by adding monomers together, process called POLYMERIZATION. -many examples of Polymers, such as: polyethylene (gloves) polystyrene (styrofoam) teflon (pans)

26. Synthetic polymers, the polymer unit, and some uses of each polymer.

27. Plastics Lab • Objective: • To compare and contrast the various chemical and physical properties of polymers. • Procedure: • Complete as many “tests” as possible on your plastic samples. You can also make combinations of tests: For example, bending after heating. • Chemical tests: Acid/Base/Alcohol/Acetone • Physical tests: Heat (hot water), bending, scratching, etc. • Results: • Data table of results-be concise! This should be put into either a “insert table” format from a word document or in an excel spreadsheet format. • This should include both “chemical” and “physical” tests. • Be sure to indicate if a plastic sample was a “high density” or “low density” sample. • Discussion: • Paragraph 1: Introduction on polymers. Explain such concepts as: What are polymers? How are they formed? Why are there so many varieties? What do the “triangle” symbols and numbers refer to on plastic products? • Paragraph 2: Explain the trends that were observed throughout the lab. Give general and specific examples of results. This is the most detailed and important part of the discussion. • “Paragraph 3”: Answer the following questions: • 1. Why are some drinks (food) available in plastics, cans and even • glass? Why would some products need to be in different types of containers? • 2. Do you see any potential problem with the amount of polymers • that are used in our world? Explain. • 3. Consider the following statement: Plastics are alike in more ways • then they are different? Do you agree or disagree and why?

28. Plastics by the Numbers

29. POLYMERS • Polymers are substances whose molecules have high molar masses and are composed of a large number of repeating units. There are both naturally occurring and synthetic polymers. Among naturally occurring polymers are proteins, starches, cellulose, and latex. Synthetic polymers are produced commercially on a very large scale and have a wide range of properties and uses. The materials commonly called plastics are all synthetic polymers. • Polymers are formed by chemical reactions in which a large number of molecules called monomers are joined sequentially, forming a chain. In many polymers, only one monomer is used. In others, two or three different monomers may be combined. Polymers are classified by the characteristics of the reactions by which they are formed. If all atoms in the monomers are incorporated into the polymer, the polymer is called an addition polymer. If some of the atoms of the monomers are released into small molecules, such as water, the polymer is called a condensation polymer. Most addition polymers are made from monomers containing a double bond between carbon atoms. Such monomers are called olefins, and most commercial addition polymers are polyolefins. Condensation polymers are made from monomers that have two different groups of atoms which can join together to form, for example, ester or amide links. Polyesters are an important class of commercial polymers, as are polyamides (nylon).

30. Types of Polymers/Recycling • POLYETHYLENE TEREPHTHALATE • Polyethylene terephthalate (PET), or polyethylene terephthalic ester (PETE), is a condensation polymer produced from the monomers ethylene glycol, HOCH2CH2OH, a dialcohol, and dimethyl terephthalate, CH3O2C–C6H4–CO2CH3, a diester. By the process of transesterification, these monomers form ester linkages between them, yielding a polyester. PETE fibers are manufactured under the trade names of Dacron and Fortrel. Pleats and creases can be permanently heat set in fabrics containing polyester fibers, so-called permanent press fabrics. PETE can also be formed into transparent sheets and castings. Mylar is a trade name for a PETE film. Transparent 2-liter carbonated beverage bottles are made from PETE. (The opaque base on some bottles is generally made of HDPE.) One form of PETE is the hardest known polymer and is used in eyeglass lenses. • POLYETHYLENE • Polyethylene is perhaps the simplest polymer, composed of chains of repeating –CH2– units. It is produced by the addition polymerization of ethylene, CH2=CH2 (ethene). The properties of polyethylene depend on the manner in which ethylene is polymerized. When catalyzed by organometallic com pounds at moderate pressure (15 to 30 atm), the product is high density polyethylene, HDPE. Under these conditions, the polymer chains grow to very great length, and molar masses average many hundred thousands. HDPE is hard, tough, and resilient. • Most HDPE is used in the manufacture of containers, such as milk bottles and laundry detergent jugs. When ethylene is polymerized at high pressure (1000–2000 atm), elevated temperatures (190–210°C), and catalyzed by peroxides, the product is low density polyethylene, LDPE. This form of polyethylene has molar masses of 20,000 to 40,000 grams. LDPE is relatively soft, and most of it is used in the production of plastic films, such as those used in sandwich bags.

31. POLYVINYL CHLORIDE • Polymerization of vinyl chloride, CH2=CHCl (chloroethene), produces a polymer similar to polyethylene, but having chlorine atoms at alternate carbon atoms on the chain. Polyvinyl chloride (PVC) is rigid and somewhat brittle. About two-thirds of the PVC produced annually is used in the manufacture of pipe. It is also used in the production of “vinyl” siding for houses and clear plastic bottles. When it is blended with a plasticizer such as a phthalate ester, PVC becomes pliable and is used to form flexible articles such as raincoats and shower curtains. • POLYPROPYLENE • This polymer is produced by the addition polymerization of propylene, CH2=CHCH3 (propene). Its molecular structure is similar to that of polyethylene, but has a methyl group (–CH3) on alternate carbon atoms of the chain. Its molar masses falls in the range 50,000 to 200,000 grams. Polypropylene (PP) is slightly more brittle than polyethylene, but softens at a temperature about 40°C higher. Polypropylene is used extensively in the automotive industry for interior trim, such as instrument panels, and in food packaging, such as yogurt containers. It is formed into fibers of very low absorbance and high stain resistance, used in clothing and home furnishings, especially carpeting.

32. POLYSTYRENE • Styrene, CH2=CH–C6H5, polymerizes readily to form polystyrene (PS), a hard, highly transparent polymer. The molecular structure is similar to that of polypropylene, but with the methyl groups of polypropylene replaced by phenyl groups (–C6H5). A large portion of production goes into packaging. The thin, rigid, transparent containers in which fresh foods, such as salads, are packaged are made from polystyrene. Polystyrene is readily foamed or formed into beads. These foams and beads are excellent thermal insulators and are used to produce home insulation and containers for hot foods. Styrofoam is a trade name for foamed polystyrene. When rubber is dissolved in styrene before it is polymerized, the polystyrene produced is much more impact resistant. This type of polystyrene is used extensively in home appliances, such as the interior of refrigerators and air conditioner housing. [For more information about this polymer, see Chemical Demonstrations: A Handbook for Teachers of Chemistry, by Bassam Z. Shakhashiri, Volume 1 (1983), page 241.]

33. Health and PlasticssiteCould all those space-age polymers be making us sick?Other health issues with plastics websiteBPA website • Choose refillable containers! Glass, for example, can be re-used for food storage. • Choose packaging that’s made from truly recyclable materials: paper, glass, metal cans. (Purchasing recycled paper products completes the recycling loop!) • Bring your own container to salad bars, yogurt shops, etc. — any place you’ll be served in plastic! • Buy in bulk, whenever possible. It’s the least-packaged option. • For wrapped foods, choose butcher paper, waxed paper or cellulose bags. • Bring cloth bags to your supermarket to carry groceries home. • Choose #1 (PETE) or #2 (HDPE) whenever plastic cannot be avoided! These are the most commonly recycled plastics. • Avoid plastics that aren’t readily recyclable: #3 (PVC), #4 (LDPE), #5 (PP), #6 (PS), #7 (often polycarbonate). • Avoid single-use, disposable packaging. • Storage • Avoid plastics that leach questionable chemicals: #3 (PVC), #6 (PS), #7 (often polycarbonate). • Avoid plastic cutlery and dinnerware. Use stainless steel utensils and look for recycled paper products. • Microwave foods and drinks in oven-proof glass or ceramic dishes with lids. Never let plastic wrap touch food while in the microwave! • When purchasing cling-wrapped foods from the supermarket or deli, slice off a thin layer where the food came into contact with the plastic and store the rest in a glass or ceramic container, or non-PVC cling wrap. • See the Plastics Product Chart (PDF) to help you identify which brands of plastic containers and wraps are safer.

34. What is BPA? • Bisphenol A (BPA) is a chemical building block that is used primarily to make polycarbonate plastic and epoxy resins. Polycarbonate plastic is a lightweight, high-performance plastic that possesses a unique balance of toughness, optical clarity, high heat resistance, and excellent electrical resistance. Because of these attributes, polycarbonate is used in a wide variety of common products including digital media (e.g., CDs, DVDs), electrical and electronic equipment, automobiles, sports safety equipment, reusable food and drink containers , and many other products • BPA website

35. Common Polymers