1. Alkenes, Alkynes & Aromatics

2.  A Group of organic compounds that consists of alkenes, alkynes and aromatic compounds. Alkene Alkyne Aromatic (Benzene ring)

3.  Alkenes contain at least 1 Carbon- Carbon double bond.  Alkynes contain at least 1 Carbon- Carbon triple bond. Ethene vs. Ethyne Same number of carbons, different number of hydrogen atoms due to the additional bond.

4.  The compounds will also have a different shape with the addition of a bond. EthaneEtheneEthyne (All angles 109.5°) (All angles 120°) (180° bond angle)

5.  Alkenes, alkynes and aromatics are all nonpolar and have similar properties to alkanes of the same length.  They generally have low melting and boiling points.  They are usually less dense than water.  As the parent chain becomes longer, the boiling and melting points increase as well as density.  Since they are nonpolar, they do not dissolve in water but they do dissolve in other nonpolar solvents.  See Table 11.1

6.  Rules  1. Name the longest continuous carbon chain that contains the double bond (alkene) or triple bond (alkyne) using prefixes.  2. Replace the –ane ending (that was for the alkane) with –ene for alkene or –yne for alkyne.  Ex. Ethane (alkane), Ethene (alkene), Ethyne (alkyne)

7.  Rules cont.  3. Number the parent chain so that the double/ triple bond has the lowest number. (We do not use the substituent this time to determine the lowest placement.)  4. Determine the substituents you have and what number(s) it falls. Place the name and number in front of the name of the parent compound.  5. Alkenes with more than 1 double bond are called alkadienes (2) or alkatrienes (3). If they have more than that, they are referred to as polyenes (many).

8.  1. Identify the parent chain (the main ring) based on the number of carbons and prefixes.  Instead of cyclo____ane it will be cyclo____ene  2. Number the parent chain so that the double bond has the 1 st position.  Identify all substituents and name them the same way as cycloalkanes.

9.  Carbon-Carbon bonds are rigid and therefore restricted in rotational movement. (Much like the cycloalkane, movement is restricted due to its ring structure)  These also form cis-trans isomers.  In alkenes, geometric isomers occur when there are 2 different groups or atoms attached to each of the double bonded carbons.

11.  If the double bonded carbon is bonded to 2 of the same groups or atoms then it is not cis- trans.  Cis-trans isomers are named like a normal alkene. The only difference is that the very first word in the name is cis or trans.

12.  Saturated fats, Unsaturated fats and Trans-fatty acids.  Vegetable oils are (unsaturated fats) and animal fats are (saturated fats)

13.  The cis for form of oleic acid is found in olive oil. This is a fat that is good for you. The less rigid, bent shape always for the body to break it down easily.  The trans form of oleic acid, called elaidic acid, has a linear, more rigid structure and is harder for the body to break up.  Most trans fats are manufactured, like margarine, packaged foods & fast food. They are fats that increase LDL (bad cholesterol).  Animal fats also have the same effect.

14. 1. Ethene- a very simple alkene, produced by ripening fruit, during the falling leaf season and plant/flower aging or stress. 2. Terpenes-(polyenes found in nature, built from isoprenes- 1 or more 5 carbon units) these can be steroids, chlorophyll and carotenoid pigments used in photosynthesis and vitamins A, D, K and E. 3. Geraniol- the scent of geraniums, made of 2 isoprene units, used in some natural insect repellants (mosquito, tick and fire ant)

15. 4. D-Limonene- the largest component of the oil from citrus fruit rinds, used as a fragrance & food additive, can be a water based cleaning product (Orange Glo) versus more toxic products

16. 5. Myrcene- found in bayberry, used in perfumes & scented candles (adds spicy aroma), trace amounts can be used as flavor in root beer 6. Retinal- form of vitamin A, can penetrate skin to help stimulate the formation of collagen & elastin; reduces wrinkles

17. 7. Farnesol- found in roses, orange blossoms, wild cyclamen & lily of the valley; was used in the 90’s in skin care products, was thought to smooth wrinkles & increase skin elasticity, reduces skin aging by promoting collagen regeneration

18.  The reactions take place at the double bond(s) and involves an addition reaction. This is the addition of 2 atoms or groups of atoms to the double bond. The major alkene addition reactions include the addition of hydrogen (H 2 ), halogens (Cl 2 or Br 2 ), water (HOH) or hydrogen halides such as (HBr or HCl).

19. + H 2 → o In this example, 2 hydrogen atoms are being added to the carbon-carbon double bond in the alkene which causes the molecule to become an alkane. One of 3 metals is needed as a catalyst (Pt, Pd or Ni). Heat or pressure may also be required in the reaction.

20.  Hydrogenation of alkynes is similar to alkenes. Two moles of H 2 versus 1 mole are added to the triple bond of the alkyne which causes it to become an alkane. + 2H2 →

21.  This process is used in the food industry to make margarine, which is hydrogenated vegetable oil. Vegetable oils are unsaturated and, therefore, contain double bonds. They have low melting points and are liquid at room temp.  Turning the double bonds into single bonds increases the melting point of the oil and it becomes a fat, which is solid at room temp.  Margarines can contain trans-fatty acids.