6/9/2015. Unit 15: Organic Chemistry Lesson 15.2: Substituted Hydrocarbons & Functional Groups

Transcription

1 1-chloropropane 2-methylpropane 1-iodobutane Ethanoic Acid Unit 15: Organic Chemistry Lesson 15.2: Substituted Hydrocarbons & Functional Groups 43 It Ain t Just Hydrocarbons There are all sorts of organic molecules. Organic molecule characteristics depend on the number, arrangement, and type of atoms. Substituted Hydrocarbons: Have replaced a hydrogen with a group of other atoms - a functional group. Functional Group any atom, group of atoms, or organization of bonds that determine specific properties of a molecule Generally the functional group is the reactive part of the molecule. Due to the functional group s presence, certain predictable properties ensue. 44 Gotta Name Em all There are millions of organic compounds. Each one needs a unique name. It s okay if one compound has two or more names. It s not okay if two compounds have the same name. Thankfully, IUPAC has solved this problem. Alkyl Halides Alkyl halides have the general formula R X, where X is a halogen and R is an alkyl group CFC s (chlorofluorocarbons) are examples of alkyl halides. A well known CFC is dichlorodifluoromethane (Freon-12) Extensively used in the past in cooling devices. 45 Alkyl Halides Another example of an alkyl halide is chloroform. In the past it was used as a surgical anesthetic but it is now a known carcinogen. Carbon tetrachloride was also used extensively in the past, until it was linked to liver damage. IUPAC Naming Rules 1. The number of carbons in the longest unbroken chain is used to determine the prefix of the parent name. 2. The position of any non-alkyl functional group is used: a. To determine the direction of carbon numbering. The functional group must be on the lowest possible numbered carbon. b. Determines the suffix of the parent name. 3. Alkyl groups get the next priority in numbering. 48 1

2 IUPAC Naming Rules (Cont.) 4. Two or more identical functional groups are specified by using a greek prefix (mono-, di-, tri-, etc.) 5. Different alkyl groups are listed in alphabetical order. 6. Halides are considered last, listed in alphabetical order, numbered like alkyl groups. Examples: Some More Examples: How to Stick a Halide on a Hydrocarbon Substitution Reactions: A saturated hydrocarbon reacts with a halogen. One hydrogen is replaced by the halogen per molecule of halogen (correct in packet). Ex: Addition Reactions: An unsaturated hydrocarbon reacts with a halogen. The halogen atoms bond to the unsaturated carbons Any Questions? More Functional Groups There are many functional groups other than halides and alkyl groups. Each one is different. Each one changes the molecules name in a specific way. You need to be familiar with every functional group on Reference Table R (and two others)!

3 A substituted hydroxyl group (R-OH) DO NOT CONFUSE WITH HYDROXIDE ION! 1. The hydroxyl group is polar. Increases solubility in water. 2. The OH is covalently bonded. Change suffix to -ol Number so hydroxyl is on lowest possible carbon There can be multiple hydroxyls on an alcohol Alcohols 55 Primary, Secondary and Tertiary Alcohols If the hydroxyl is on a carbon bonded to 0 or 1 carbon, it is a primary alcohol. If the hydroxyl is on a carbon bonded to 2 other carbons, it is a secondary alcohol. If the hydroxyl is on a carbon bonded to 3 other carbons, it is a tertiary alcohol. 56 Alcohols The most simple alcohol is methanol Also called methyl alcohol or wood alcohol. (poisonous) Another common alcohol is ethanol. (CH 3 CH 2 OH) Also known as ethyl alcohol or grain alcohol Least toxic and most important of the alcohols Ethanol is used in alcoholic beverages, perfumes, dyes, and varnishes. Other Alcohol Examples Rubbing alcohol is another alcohol example. Also known as 2- hydroxypropane or isopropyl alcohol Ethylene glycol is an alcohol used widely as an antifreeze and coolant. 57 Carbohydrates Compounds that contain multiple hydroxyl groups in their molecular structure. Names end in -ose Sugars, starches, and cellulose are the most important t carbohydrates. Structures of Glucose, Fructose, and Sucrose Glucose & Fructose bond together to form Sucrose + H 2 O Glucose (C 6 H 12 O 6 ) and fructose (C 6 H 12 O 6 ) are important sugars. Note that glucose and fructose are isomers. 3

4 Ethers Oxygen between two alkyl groups (R 1 -O-R 2 ) Formed by a dehydration reaction (removal of water) between two primary alcohols: R-OH + HO-R R-O-R + H 2 O Name is (R 1 )(R 2 ) ether Names of groups in alphabetical order Ethers Diethyl ether is the one commonly called just ether was the first reliable general anesthetic dangerous- highly hl flammable, also causes nausea ethers are fairly soluble in water less than their isomers the alcohols 61 Aldehydes and Ketones Review: alcohol has an oxygen bonded to a carbon group and a hydrogen ether has an oxygen bonded to two carbon groups An oxygen can also be bonded to a single carbon by a double bond Aldehydes and Ketones The C=O group is called the carbonyl group it is the functional group in both aldehydes and ketones Carbonyl group always joined to at least one hydrogen (meaning it is always on the end! On primary carbon) General Formula : R-CHO identify longest chain containing the carbonyl group, then the -e ending replaced by -al, such as methanal, ethanal, etc. Aldehydes Ketone A carbonyl group (R 1 -CO-R 2 ) on a secondary carbon. The O is double bonded to the C. longest chain w/carbonyl, then new ending of -one; number it so carbonyl is on lowest possible carbon propanone, 2-pentanone, 3-pentanone

5 Aldehydes and Ketones Neither can form intermolecular hydrogen bonds, thus a much lower b.p. than corresponding alcohols wide variety have been isolated from plants and animals; possible fragrant odor or taste; many common names A carboxyl group (R-COOH) One O is double bonded to the C. 1. The H on the end dissociates in water 2. The shorter the R, the stronger the acid Change suffix to -oic acid A carboxyl can not be on anything other than the first carbon. Organic Acids Acetic Acid! Yay Vinegar! 68 Esters Amines Carboxyl (no H) between two alkyl groups (R 1 -COO-R 2 ) A product of dehydration reaction between an organic acid and an alcohol What give fruits their smells! Name is (R 1 )(R 2 )-oate R group that was the acid second. 69 A Nitrogen with three attached things, usually 1 carbon and two hydrogens (R-NH 2 ) 1. Can accept a proton (BL Base) 2. Can be primary, secondary or tertiary, like alcohols. Change suffix to -amine Number so amine is on lowest possible carbon 70 Amines Strong Odors Amides Most simple amines have strong odors. The odor given off by raw fish is due to an amine that it contains. Two particularly foul smelling amines are formed by decaying flesh. Cadaverine (1,5-diaminopentane) Putresine (1,4-diaminobutane) Amides are nitrogen-containing organic compounds with the general formula RCONHR. Change suffix to -amide Has to be on a primary carbon. 5

6 Amide Formation Amide formation is similar to ester formation. A carboxylic acid reacts with an amine to form water and an amide, as shown below. Amino Acids Molecules with an amine on one end and a carboxyl (acid)group on the other end. 20 amino acids make all proteins used in all biological cells on the planet. Instructions for amino acid sequences in proteins are encoded in DNA. 74 Fats Fats are a type of ester formed by the combination of the trialcohol named glycerol and fatty acids. Glycerol is CH 2 (OH)CH(OH)CH 2 (OH) Stearic Acid (C 17 H 35 COOH) is found in beef fat, and is a typical fatty acid. Fats Generally fats from animals are solid at room temperature. Fats from plants and fish are generally liquid at room temperature. Liquid fats are referred to as oils. Hydrogenation Liquid fats contain double bonds between some of the carbon atoms. These liquids fats are termed unsaturated. Hydrogenation When Cottonseed Oil (liquid) is hydrogenated, Margarine (solid) is the result. Hydrogenation is the process of adding H to the C atoms that have a double bond. The hydrocarbon chains become saturated or nearly saturated and the liquid fat is changed to a solid. A common example of hydrogenation is the reaction cottonseed oil to margarine. 6

7 Soaps Soap the sodium slats of fatty acids Soap is formed by reacting a fat with sodium hydroxide (NaOH, lye.) The ester bonds break giving rise to glycerol and sodium salts of the fatty acids. Sodium stearate t is a typical soap. Soap Like Dissolves Like Generally we want to dissolve stains made by nonpolar compounds such as grease. The polar end of the soap dissolves in water. The other end of the soap molecule is long and nonpolar. This nonpolar end dissolves in the grease. The emulsified grease droplets can be rinsed away. The long nonpolar chains of the detergent molecule dissolve the grease. Enough! What Do You Need To Be Able To Do?!? 1. Be able to recognize the family a molecule belongs to. 2. Be able to name simple examples of each kind of family. No soaps or amino acids. 3. Be able to draw isomers of the various groups. Even between isomeric families. 82 Any Questions? What now? 83 7