Aim: Sorting Out Organic Compounds!

Transcription

1 Name: Organic Chemistry Organic chemistry is a highly creative science in which chemists create new molecules and explore the properties of existing compounds. There are at least nine million organic compounds. Over 300,000 new are synthesized each year! Aim: Sorting Out Organic Compounds! 1

2 Defining Organic Chemistry What factors are responsible for the tremendous number of organic compounds? What makes all of these compounds different? Building organic molecules using models can help us understand the basic structures of organic compounds. Background Information: The term organic chemistry refers to the study of compounds containing carbon. The most common elements found with carbon are hydrogen, oxygen, nitrogen, phosphorus, and the halogens. Organic compounds, then, can be defined as covalently bonded compounds containing carbon, excluding carbonates and oxides. The name reflects the historical roots of chemistry it was thought that compounds obtained from living organisms required a vital force for their existence. The notion was discarded in 1828, when the first organic compound was synthesized in the lab, but the name organic chemistry remains. Carbon is unique among the elements because of the large number of diverse structures of compounds that it forms. Several factors help explain why compounds containing carbon are well-suited to the chemistry of life: Carbon forms strong and stable bonds with other carbon atoms. Chains of carbon atoms can close in on themselves to form rings in addition to chains. Many different ring sizes are possible, but five-, six-, and seven-membered rings are the most common. The valency of carbon is four carbon forms four covalent bonds to achieve a stable octet. Using your glossary define organic chemistry: List examples of organic compounds: 2

3 Procedure: The purpose of this activity is to build organic molecules using models. The models will be used to draw structural formulas of organic compounds, determine the general formulas for different classes of hydrocarbons, and develop the concept of isomers of organic compounds. Review: Complete the table below using your molecular modeling kit and Periodic Table. Element Number of valence e - Lewis Dot Structure Number of Bonding Sites Color of atom in modeling kit Hydrogen Oxygen Nitrogen Carbon The HONC-1234 Rule Every Hydrogen has 1 bond connecting it to other atoms. Every Oxygen has 2 bonds connecting it to other atoms. Every Nitrogen has 3 bonds connecting it to other atoms. Every Carbon has 4 bonds connecting it to other atoms. Based on the video and background information, answer the following questions: 1. What is the common element in all organic compounds? 2. Identify five other elements frequently found bonded to carbon in organic compounds. 3. Give two examples of carbon-containing molecules that would not be considered organic. (a carbonate compound) & (an oxide compound) 3

4 Exploring Organic Compounds Using your molecular model building kit, create four different organic compounds. Using the colored pencils, sketch your molecules below and determine their molecular formulas. Remember to follow the HONC-1234 Rules! Create a 5-carbon hydrocarbon that is an alkane. A hydrocarbon is a molecule containing only carbon and hydrogen. An alkane has only single bonds. Create a halocarbon that is an alkane. A halocarbon is a molecule containing only carbon, hydrogen, & a halogen. Molecular Formula: Molecular Formula: IUPAC Name: IUPAC Name: Interesting fact: Interesting fact: Create a 6-carbon hydrocarbon that is an alkene. An alkene has at least one double bond. Create a 3-carbon hydrocarbon that is an alkyne. An alkyne has at least one triple bond. Molecular Formula: Molecular Formula: IUPAC Name: IUPAC Name: Interesting Fact: Interesting Fact: Describe two factors that account for the multitude of organic compounds. 4

5 Properties of Organic Compounds 1. Carbon has valence electrons and can therefore form covalent bonds. Draw each structure and add hydrogen atoms as needed in the table below. (1) (3) (2) (4) 2. Carbon s bonds may be,, or. Series, Series, Series 3. Most organic compounds are or weakly polar. a. IMF present in nonpolar molecules: b. Low and points. c. High vapor pressure ( ). d. /immiscible in water, but soluble in solvents, such as carbon tetrachloride & benzene. 4. except for organic acids in the aqueous state. 5. Organic reactions, being complex, are much than inorganic reactions. Many organic reactions require a catalyst to speed up the rate of reaction. 5

6 Applying Your Knowledge Practice Regents Questions 1. Organic compounds differ from inorganic compounds in that organic compounds generally have (1) high melting points and are electrolytes (2) high melting points and are nonelectrolytes (3) low melting points and are electrolytes (4) low melting points and are nonelectrolytes 2. Which element is composed of atoms that can form more than one covalent bond with each other? (1) hydrogen (2) helium (3) carbon (4) calcium 3. Draw an electron dot diagram of methane (CH4) in the space below. 4. Is water an appropriate solvent for methane? Why or why not? 5. Hydrocarbons are compounds that contain (1) carbon, only (2) carbon and hydrogen, only (3) carbon, hydrogen, and oxygen, only (4) carbon, hydrogen, oxygen, and nitrogen, only 6. Which structural formula correctly represents a hydrocarbon molecule? (1) (2) (3) (4) 7. Organic compounds that are essentially non-polar and exhibit weak intermolecular forces have (1) low vapor pressure (3) low melting points (2) high melting points (4) high electrical conductivity in solution 6. In general, which property do organic compounds share? (1) high melting point (3) high electrical conductivity (2) readily soluble in water (4) slow reaction rate 6

7 How can organic compounds be classified? Hydrocarbons Aromatic Aliphatic Aromatic Hydrocarbons Compound Name Molecular Formula Structural Formula Line Representation 7

8 Aliphatic Hydrocarbons Alkanes Alkenes Alkynes Using your glossary, define the following terms: Homologous Series Saturated Hydrocarbon Example: Unsaturated Hydrocarbon Example: Which Table in your reference tables refers to the different homologous series in organic chemistry? Which series is classified as saturated hydrocarbons? Which series are classified as unsaturated hydrocarbons? & Which Table in your reference tables refers to the prefixes used to identify the number of carbon atoms in a compound? 8

9 How are branched hydrocarbons named? 1. The number of carbons in the longest continuous unbroken chain is used to determine the prefix of the parent chain. 2. The position of any alkyl group is considered next. To name the alkyl group, use the prefix for the number of carbons in the alkyl group, replace the -ane suffix with -yl. 3. Use a number to identify which carbon the alkyl group is attached to. Remember to number the carbons so that the alkyl group is on the LOWEST number ( shortest address ). Example: IUPAC Name: 4. When there is more than one of the same type of alkyl group branching off of the main carbon chain, use the Greek prefixes to indicate how many, i.e., di- (2); tri- (3); tetra- (4); and so on. The position of the alkyl groups is also specified using numbers. Example: IUPAC Name: 5. When different alkyl groups are present on the chain, they are given in alphabetical order. Example: IUPAC Name: 9

10 6. In unsaturated compounds, the double or triple bond MUST be included in the main chain. Even with alkyl groups present, the double/triple bond is assigned the lowest possible number. Alkyl groups are named first, and double/triple bonds are named after. Example: IUPAC Name: Practice Naming These Hydrocarbons Directions: Name the compounds below according to the IUPAC naming system. Be sure to HIGHLIGHT the parent chain and NUMBER THE CARBONS first! Find the longest possible chain, giving the substituents (i.e., alkyl groups) the lowest possible address. CH 3 CH 3 CH 3 CH 3 CH CH 2 CH CH 3 CH CH CH IUPAC NAME: CH 3 CH 3 CH 2 C CH 3 IUPAC NAME: CH 3 CH CH 3 CH CH 2 CH CH 2 CH 2 CH 3 4 CH 2 CH 2 5 CH 3 CH 3 IUPAC NAME: IUPAC NAME: 10

11 CH 3 CH 2 CH C CH 2 CH 3 CH 3 CH 3 IUPAC NAME: CH 3 CH C C CH 3 IUPAC NAME: 6 7 CH 2 CH CH 3 CH CH 3 C C CH 2 CH 3 CH 2 CH CH 3 CH 2 C C CH 2 CH 3 CH 3 IUPAC NAME: IUPAC NAME: Practice Drawing These Hydrocarbons Draw the structural representation of each compound below. Remember: Each carbon bonds four times! 2-methylpentane 1-butyne 1,4-pentadiene (Hint: This means that there are two double bonds!) 3-methyl-1-butyne 3,3-dimethyl pentane 2-ethyl-1-pentene 11

12 2,2,4,4-tetramethylpentane 2-ethyl-3-methyl-1-butene FRACTIONAL DISTILLATION Crude oil can be refined to produce usable products such as gasoline, diesel and various forms of petrochemicals. The various components of crude oil have different sizes, weights and boiling temperatures; so, the first step is to separate these components. Instructions: Watch the YouTube videos about fractional distillation and cracking using your ipad, phone or computer to answer the questions. Then use the diagram below and your knowledge of hydrocarbons to complete the table. 1. What is crude oil? (Add to this definition at 1:11.) 2. Where is crude oil harvested? 3. What does crude oil provide us with? 4. As the length of molecules increases, what happens to IMF? 5. Compare the boiling point of short hydrocarbons to the boiling point of long hydrocarbons. 6. Summarize the process of fractional distillation. 7. What is a fraction? 12

13 1. Using the diagram at right, what is the boiling point of pentane? 2. What can pentane be used for? 10. Identify another hydrocarbon that is part of the same fraction as pentane. Molecular formula: IUPAC Name: Practice Regent Question: Crude oil is a mixture of many hydrocarbons that have different numbers of carbon atoms. The use of a fractionating tower allows the separation of this mixture based on the boiling points of the hydrocarbons. To begin the separation process, the crude oil is heated to about 400 C in a furnace, causing many of the hydrocarbons of the crude oil to vaporize. The vaporized mixture is pumped into a fractionating tower that is usually more than 30 meters tall. The temperature of the tower is highest at the bottom. As vaporized samples of hydrocarbons travel up the tower, they cool and condense. The liquid hydrocarbons are collected on trays and removed from the tower. The diagram below illustrates the fractional distillation of the crude oil and the temperature ranges in which the different hydrocarbons condense. 1. State the trend between the boiling point of the hydrocarbons contained in the crude oil and the number of carbon atoms in these molecules. 2. Describe the relationship between the strength of the intermolecular forces and the # of carbon atoms in the different hydrocarbon molecules. 3. Write an IUPAC name of one saturated hydrocarbon that leaves the fractionating tower at less than 40 C. 13

14 4. How many hydrogen atoms are present in one molecule of octane? HYDROCARBON CRACKING Cracking in petroleum refining, the process by which heavy hydrocarbon molecules are broken up into lighter molecules by means of heat and usually pressure and sometimes catalysts. 1. What is crude oil a mixture of? 2. Shorter Hydrocarbon Chains Longer Hydrocarbon Chains 3. Why is there a demand for short-chain hydrocarbons? 4. What does the process of cracking do? 5. Why is this beneficial? 6. What are the longer hydrocarbon chains broken down into? & 7. The alkanes are used for fuels. What can the alkenes be used for? 8. Write two possible equations for the cracking of octane: Chemical Formula: Word Formula: Chemical Formula: Word Formula: 9. What are the two types of cracking? & 14

15 What is an Isomer? How can two different compounds have the same molecular formula, but different structures & different physical structures & chemical properties? Butane Structural Formula Methylpropane Structural Formula Molecular Formula Molecular Formula Isomers IUPAC name: Pentane Draw all possible isomers for pentane. IUPAC name: IUPAC name: Structural Diagram: Structural Diagram: Structural Diagram: Molecular Formula: Molecular Formula: Molecular Formula: 15

16 Draw the 5 isomers for hexane (including hexane) and name them. IUPAC Name: Hexane IUPAC Name: IUPAC Name: IUPAC Name: IUPAC Name: 16

17 Functional Groups Functional groups are collections of atoms in organic chemistry molecules that contribute to the chemical characteristics of the molecule and participate in predictable reactions. These groups of atoms contain oxygen or nitrogen or sometimes sulfur attached to a hydrocarbon skeleton. Organic chemists can tell a lot about a molecule by the functional groups that make up a molecule. Table R Organic Functional Groups Class of Compound Functional Group General Formula Example - F (fluoro-) Halide - Cl (chloro-) R-X CH3CHClCH3 (halocarbon) - Br (bromo) (X represents any 2- chloropropane - I (iodo-) halogen) Example #1 Example #2 2,3 dibromopentane Trichloromethane (chloroform) Class of Compound Functional Group General Formula Example Alcohol (a.k.a. hydroxyl group) Example #1 2-pentanol -OH R - OH CH3CH2CH2OH 1-propanol Example #2 1,2 pentandiol 17

18 PRIMARY, SECONDARY, & TERTIARY ALCOHOLS Classifying alcohols based on the number of R-groups that are attached to the carbon attached to the hydroxyl group (-OH) Type of Alcohol Primary Alcohol Secondary Alcohol Tertiary Alcohol General Formula # of carbons attached to the C-OH Example (Structural Formula & IUPAC Name) MONOHYDROXY, DIHYDROXY, & TRIHYDROXY ALCOHOLS Classifying Alcohols Based on Number of Hydroxyl Groups Monohydroxy Alcohols (Contain hydroxyl (-OH) group.) methanol ethanol 2-propanol Structural Formula: Structural Formula: Structural Formula: 18

19 Dihydroxy Alcohols (Contain hydroxyl (-OH) groups.) 1,2-ethandiol Structural Formula: 1,4-butandiol Structural Formula: Trihydroxy Alcohols (Contain hydroxyl (-OH) groups.) 1,2,3-propantriol (a.k.a. glycerol/glycerin) Structural Formula: 1,3,5-hexantriol Structural Formula: Practice Regents Questions 1. When the name of an alcohol is derived from the corresponding alkane, the final -e of the name of the alkane should be replaced with a) -al b) -ole c) -one d) -ol 2. To be classified as a tertiary alcohol, the functional OH group is bonded to a carbon atom that must be bonded to how many additional carbon atoms? a) 1 b) 2 c) 3 d) 4 3. Which is the structural formula of a dihydroxy alcohol? 4. Which is the structural formula of a primary alcohol? 5. Which is the structural formula of a secondary alcohol? 19

20 6. All three of the following alcohols can be classified as a) secondary alcohols b) monohydroxy alcohols c) tertiary alcohol d) primary alcohols 7. Which compound is a dihydroxy alcohol? a. C3H5(OH)3 b. C2H4(OH)2 c. Al(OH)3 d. Ca(OH)2 8. What is the total number of OH groups in a molecule of glycerol? a. 1 b. 2 c. 3 d. 4 Class of Compound Functional Group General Formula Example Aldehyde (a.k.a. carbonyl group) Aldehydes contain a terminal carbonyl group Example #1 Hexanal O -C-H O R-C-H O CH3CH2C-H propanal Example #2 Methanal (a.k.a formaldehyde) Class of Compound Functional Group General Formula Example Ketone Contains an internal (nonterminal) carbonyl group O -C- O R-C-R O CH3CCH2CH2CH3 2- pentanone Example #1 3-pentanone Example #2 2-hexanone 20

21 Class of Compound Functional Group General Formula Example Organic Acid (a.k.a. carboxyl group) O -C-OH O R-C-OH O CH3CH2C-OH Example #1 methanoic acid (formic acid) Example #2 pentanoic acid Practice Regents Questions: 1. Methanal is the IUPAC name for an a) acid b) alcohol c) ketone d) aldehyde 2. Which organic compound is an acid? (Hint: Use Table Q/Draw structural diagrams to help you.) a) CH3OH b) CH3OCH3 c) CH3COOCH3 d) CH3COOH 3. Which structural formula represents a ketone? 4. What is the correct IUPAC name for the following structure? a) 2,4-dichlorobutane b) 2,4-dichloropentane c) 1,3-dichloropentane d) 1,3-dichlorobutane 21

22 Class of Compound Functional Group General Formula Example Amine (a.k.a. amino group) Example #1 2-butanamine -N- R R-N-R Example #2 1-pentanamine CH3CH2C-NH2 1-propanamine Class of Compound Functional Group General Formula Example Amide (Contains a terminal - CONH 2 group.) Example #1 pentanamide O -C-N O R R-C-NH Example #2 butanamide O CH3CH2C-NH2 propanamide Class of Compound Functional Group General Formula Example Ether -O- R-O-R CH3OCH2CH3 Methyl ethyl ether Example #1 Dimethyl ether Example #2 Ethyl propyl ether 22

23 Class of Compound Functional Group General Formula Example Ester O O Example #1 Propyl methanoate O -C-O- R-C-O-R Example #2 Ethyl butanoate CH3CH2COCH3 methyl propanoate Comparing Different Functional Groups Name Functional Group Structural Formula Boiling Point ( 0 C) Butane None Butanol Butanoic Acid Butanone 79.6 Diethyl ether 34.5 What is similar? Describe differences: 23

24 Do Now: The following examples illustrate the great variety of functional groups present in organic compounds. Circle and label the organic functional groups in the following compounds. An example has been done for you. 1. Functional Group: Ether 2. IUPAC Name: Dimethyl ether Functional Group: 3. IUPAC Name: Functional Group: 4. IUPAC Name: Functional Group: 5. IUPAC Name: Functional Group: 6. IUPAC Name: Functional Group: 7. IUPAC Name: Functional Group: IUPAC Name: 24

25 Draw the following structures (structural or condensed structural) Propanoic acid Methanal Methylmethanoate Dimethyl ether 2-propanamine ethanamide What types of reactions to hydrocarbons undergo? I. Combustion: Example: Write the balanced equation for the combustion of methane (Table I): II. Substitution: General Formula: If a saturated hydrocarbon (alkane) is reacted with a halogen, one of the halogen atoms replaces hydrogen on the hydrocarbon chain. The hydrogen get replaced ONE AT A TIME. Substitution Example #1: Ethane + Fluorine! Fluoroethane + Hydrogen fluoride gas Structural Diagram Representation: 25

26 Substitution Example #2: Butane + Bromine! + Structural Diagram Representation: III. Addition Reactions: If an unsaturated hydrocarbon (alkene or alkyne) is reacted with a halogen, water or binary compound such as HCl, the mechanism of the reaction is such that the multiple bond is broken, and the halogen adds on at the site of the newly available bonds. Addition Example #1: Ethene + Fluorine! Structural Diagram Representation: Addition Example #2: 1-Butyne + Hydrogen Cloride! Structural Diagram Representation: 26

27 Practice Regents Questions 1. What type of reaction is represented by the equation below? a) substitution b) esterification c) fermentation d) addition 2. In which type of reaction can an unsaturated hydrocarbon become saturated? a) substitution b) esterification c) fermentation d) addition 3. The products of the complete combustion of a hydrocarbon are water and a) carbon dioxide b) an aldehyde c) an alcohol d) carbon 4. Which compound will undergo a substitution with bromine? a) C3H6 b) CH4 c) C4H8 d) C2H4 5. In the reaction, what is the structural formula of the product represented by X? IV. Esterification General Formula: + <----> + H2O Esterification is a dehydration synthesis reaction between an organic acid and an alcohol, where a water molecule is removed and an ester is formed. Esters typically have pleasantsmelling aromas, such as wintergreen, banana, pineapple, and pear. Esterification Example #1: propanoic acid + methanol! + water Structural Diagram Representation: 27

28 Esterification Example #2: ethanoic acid + 1-butanol! + water Structural Diagram Representation: Practice Regents Questions 1. An alcohol and an organic acid are combined to form water and a compound with a pleasant odor. This reaction is an example of a) saponification b) esterification c) polymerization d) fermentation 2. Which equation represents an esterification reaction? a) C5H10 + H2! C5H12 b) C6H12O6! 2C2H5OH + 2CO2 c) C3H8 + Cl2! C3H7Cl + HCl d) HCOOH + CH3OH! HCOOCH3 + HOH V. Polymerization: Addition Polymerization Monomers react by addition to form polymers. In order to undergo addition, the reactants must be unsaturated (contain double or triple bonds). Polyethylene n(c2h4)! (C2H4)n Condensation Polymerization Monomers that have functional groups that contain O and H react to form polymers by dehydration synthesis (the removal of water). Nylon Ropes 28

29 Natural Polymers A natural polymer has its origin in plants and animals. Examples: Starch, cellulose, proteins, and natural rubber Synthetic Polymers Describes man-made polymers or the polymers which are synthesized in the laboratory Examples: Polyethylene, polyvinyl chloride, nylon, and synthetic rubbers. Practice Regents Questions 1. The chaining together of small molecules (monomers) to form a large molecule (polymer) occurs during the process of a) substitution b) fermentation c) saponification d) polymerization 2. The reaction nc2h4! (C2H4)n is best described as a) substitution b) fermentation c) saponification d) polymerization 3. The process of opening double bonds and joining monomer molecules to form polyvinyl chloride is called a) addition polymerization b) dehydration polymerization c) condensation polymerization 4. Condensation polymerization is best described as a) an oxidation rxn b) a cracking rxn c) a dehydration rxn d) a reduction rxn 5. Cellulose is an example of a) a synthetic polymer b) a natural polymer c) an ester d) a ketone VI. Fermentation: Fermentation is the decomposition of glucose or fructose into an ethanol and carbon dioxide. Yeast and enzymes such as zymase facilitate this process. General Formula: +! + Example: Fermentation of Glucose Word Equation:! + Chemical Equation:! + 29

30 VII. Saponification: Saponification is the splitting of a fat by a strong base (i.e., NaOH) to produce glycerol and soap molecules. General Formula: +! + 1. The reaction that occurs when a hydrocarbon is heated in the presence of oxygen is called a) combustion b) fermentation c) saponification d) vulcanization 2. The cross-linking of rubber molecules with sulfur to toughen it is called a) combustion b) fermentation c) saponification d) vulcanization 3. The reaction that is used to manufacture soap is called a) combustion b) fermentation c) saponification d) vulcanization 4.The reaction that produces ethanol by the digestion of sugars by yeast is called a) combustion b) fermentation c) saponification d) vulcanization 5. Which reaction can be used to make 2,3-dichloropentane? a) addition b) substitution c) etherification d) esterification 6. Which reaction can be used to make propyl ethanoate? a) addition b) substitution c) etherification d) esterification 7. What is a by-product of saponification? a) ethanoic acid b) propanone d) ethylene glycol d) glycerol 30

31 Practice: Types of Reactions 1. Identify the type of rxn by writing it in the specified box. Each type of reaction occurs only once. Reaction Type of Reaction C2H4 + Cl2! C2H4Cl2 CH3OH + CH3COOH! CH3COOCH3 + H2O CH4 + 2O2! CO2 + 2H2O C6H12O6!2C2H5OH + 2CO2 C3H8 + HBr! C3H7Br + H2 CH3OH + CH3OH! CH3OCH3 + H2O 1200 C2H4! -(-C2H4-)