Organic Chemistry Expectations - Introduction & Review PDF

Organic Chemistry Expectations Big Ideas * Organic compounds have predictable chemical and physical properties determined by their respective structures * Organic chemical reactions and their applications have significant implications for society, human health, and the environm...

Organic Chemistry Expectations Big Ideas * Organic compounds have predictable chemical and physical properties determined by their respective structures * Organic chemical reactions and their applications have significant implications for society, human health, and the environment Relating Science to Technology, Society, and the Environment * Assess the impact on human health, society, and the environment of organic compounds used in everyday life (e.g., polymers, nutritional supplements, food additives, pesticides, pharmaceuticals) * Propose a course of action to reduce the use of compounds that are harmful to human health and the environment Knowledge * Compare hydrocarbons, ethers, alcohols, aldehydes, ketones, carboxylic acids, esters, amines, amides by describing similarities and differences in names and structural formula of the compounds in each class * Describe similarities and differences in physical properties (melting point, boiling point, odour, solubility in different solvents) for each class * Explain the chemical changes that occur during substitution, addition, elimination, oxidation, esterfication, and hydrolysis * Explain the difference between addition and condensation polymerization reactions * Explain isomers and how variations in properties relate to structural and molecular formula Inquiry * Analyse through inquiry various organic reactions (e.g. production of esters, polymerization, oxidation of alcohols, combustion reactions, addition reactions, multiple bonds Communication * Use terminology including organic compound, functional group, saturated HC, unsaturated HC, structural isomer, sterioisomer, and polymer * Use IUPAC to identify names, write formula, and create structural formula for classes of organic compounds * Build models of simple organic compounds  Organic Chemistry Organic vs. Inorganic Chemistry Organic chemistry is defined as the chemistry of carbon based compounds. Inorganic chemistry is associated with the study of compounds which do not involve carbon. Common inorganic compounds include table salt (NaCl), hydrochloric acid (HCl), and water (H2O). Interestingly enough, carbon monoxide (CO) and carbon dioxide (CO2) are classified as inorganic compounds. Cyanides (KCN), carbides (Ca2C), and carbonates (CaCO3) are also considered to be inorganic. Hydrocarbons Hydrocarbons are organic compounds which consist only of the elements hydrogen and carbon. Examples include methane (CH4), acetylene (C2H2), and wax (C25H52). Origins of Hydrocarbons When pre-historic plants and animals died, bacteria removed oxygen and nitrogen atoms leaving carbon and hydrogen behind. Over time, mud and sediment produced pressure and heat which transformed these remains into fossil fuels. Today, fossil fuels can be found below the surface of the earth and at the bottom of rivers, lakes, and ocean beds. Fossil Fuel Origin Coal Solid remains from land animals Petroleum (crude oil) Liquid remains from marine life Natural gas Gas produced as petroleum vaporizes Today, fossil fuels, plants fermentations, and wood are sources of hydrocarbons. Assignment Identify the following as organic or inorganic. Write HC beside any hydrocarbons. a) C2H6 b) SO2 c) LiCN d) C6H12O6 e) C3H8 f) C2H5OH g) C6H6 h) MgCO3 Characteristics of the Methane (CH4) Molecule H C H H H IUPAC name: methane Formula: CH4 VSEPR structure: tetrahedral Bond angle: 109.5o Symmetry: symmetric Intramolecular bond type: non-polar covalent Molecular polarity: non-polar The difference in electronegativity between carbon and hydrogen atoms is 0.35 (2.55-2.20). In general, a number less than 0.5 represents a non-polar bond. All 4 intramolecular bonds are non-polar and there are no non-bonding electron pairs around the central atom. As a result, the molecule is symmetric and non-polar. Hydrocarbons are non-polar molecules. Types of Diagrams Molecular formula: C4H10 Expanded molecular formula: CH3CH2CH2CH3 Complete structural diagram: H H H H H C C C C H H H H H Condensed structural diagram: CH3 — CH2 — CH2 — CH3 Structural line diagram: butane benzene Classifying Organic Compounds Organic compounds can be classified according to one of the following 4 general skeletal structures. Aliphatic Consist of carbon atoms linked together in an open chain. H H H H H H Eg. H - C - C - C - C - C - C - H H H H H H H C H H Alicyclic Consist of carbon atoms joined together forming a ring. H H C H H C C Eg. H H C C H H H H Aromatic Structures that are related to benzene where electrons are delocalized around the ring. C C C C C C C C C C C (benzene) C Eg. H H N C C C (aniline) C C C Heterocyclic Consist of a ring structure incorporating atoms such as oxygen, sulfur and phosphorus. H H Eg. C C H H O Alkanes Alkanes are considered to be the simplest type of hydrocarbon. They are saturated because all atoms are bonded to one another by single bonds. Multiple bonds (double or triple) are not present. Alkanes possess the following general formula: Cn H2n+2 where n = 1, 2, 3,..... Simple Alkane Series n CnH2n+2 IUPAC Name 1 CH4 methane 2 C2H6 ethane 3 C3H8 propane 4 C4H10 butane 5 C5H12 pentane 6 C6H14 hexane 7 C7H16 heptane 8 C8H18 octane 9 C9H20 nonane 10 C10H22 decane Structural Diagrams of Simple Alkanes H H C H methane (CH4) H CH4 H H H C C H ethane (CH3CH3) H H C2H6 H H H H C C C H propane (CH3CH2CH3) H H H C3H8 H H H H H C C C C H butane (CH3CH2CH2CH3) H H H H C4H10 Conformations Conformations are molecules that have the same molecular formula but their structures differ as a result of rotation about C—C single bonds. H H H H C C H H H C H C H H H H eclipsed staggered A seemingly infinite number of intermediate conformations are called skew conformations, all equally likely to occur. As a result, a sample of ethane gas consists of eclipsed, staggered, and skew conformations. Alkyl Groups Alkyl groups are neutral species formed when a hydrogen atom is removed from an alkane. They are referred to as radicals because they posses unpaired electrons which are represented by dots. H H H C H H C H H (methane) (methyl radical) CH3 (methyl) CH2CH3 (ethyl) CH2CH2CH3 (propyl) CH3 CH CH3 (isopropyl) CH2CH2CH2CH3 (butly) Properties and Uses of Simple Alkanes Alkanes are unreactive since they do not possess a functional group. They are colourless, odourless, and have a low solubility in water because they consist of non-polar molecules. Since alkanes burn, they participate in combustion reactions. These reactions are highly exothermic (release energy) and that is why alkanes are commonly used as fuels. Alkane Use CH4 - natural gas (used to heat homes) C2H6 - natural gas C3H8 - propane (backyard BBQ’s, portable camp stoves) C4H10 - butane (cigarette lighters) C8H18 - (automobile & plane fuel) C9H20 - Higher molecular weight alkanes - oil furnaces, lubricating oils, grease, wax candles, waxed paper, cosmetics, asphalt, tar Complete and Incomplete Combustion Combustion of methane CH4 + 2 O2 --------> CO2 + 2 H2O Combustion of octane 2 C8H18 + 25 O2 --------> 16 CO2 + 18 H20 The complete combustion of any hydrocarbon will always result in the production of water & carbon dioxide. Incomplete combustion will result in the production of carbon and carbon monoxide. Carbon deposits decrease the effectiveness of spark plugs in automobile engines while carbon monoxide is a poisonous gas that can be fatal if inhaled in large quantities. Incomplete combustion of ethane C2H6 + O2 --------> CO2 + H2O + C + CO Explaining the Trends in the Melting & Boiling Points of Alkanes Alkane State Melting Point Boiling Point (/C) (/C) methane gas -182 -161 ethane gas -183 -89 propane gas -188 -42 butane gas -138 -0.5 pentane liquid -130 36 octane liquid -57 125 decane liquid -30 174 eicosane (C20H42) solid 37 343 triacontane (C30H62) solid 66 446 In comparing the boiling and melting points of alkanes, it becomes quite apparent that these characteristic properties generally increase as the value of n increases. Why ? * Hydrocarbons are non-polar molecules * Hydrocarbon molecules are attracted to one another by the extremely weak van der Waals forces * As the value of n increases, the molecules become larger * Larger molecules possess more VDW forces * If there are more forces of attraction, then more energy is required to break these forces of attraction. As a result, melting and boiling points increase A Strategy for Naming Alkanes (IUPAC Nomenclature) 1. Identify the longest continuous chain of carbon atoms. This parent hydrocarbon is the framework to which various groups (substituents) are attached. * If more than 1 chain can be identified as the parent chain (because they are the same length), choose the chain which has more branches (substituents). Examples CH 3 i) CH 2 CH 2 CH 3 ii) CH 3 CH CH CH 2 CH 3 CH 3 CH 2 CH CH 3 CH CH 3 CH 3 3 possible chains ------> 4 C’s Chain that results in the greatest ------> 5 C’s number of branches. ------> 6 C’s 2. Number the carbon atoms forming the longest continuous chain from one end to the other so that the smallest possible numbers are used to designate the position of the substituents. If there is more than one way of obtaining the smallest number combination, choose the option which gives alphabetical priority to one of the substituents. (e.g. 2-ethyl-4-methylpentane) Examples 4 5 6 CH 3 1 2 3 i) CH 2 CH 2 CH 3 ii) CH 3 CH CH CH 2 CH 3 CH 3 CH 2 CH CH 3 4 CH CH 3 1 2 3 5 CH 3  3. Identify the substituents that are attached to the parent chain and note the numbers associated with the carbon atoms to which they are attached. Examples -F (fluoro) -CH 3 (methyl) -OCH 3 (methoxy) -Cl (chloro) -C 2 H 5 (ethyl) -OCH 2 CH 3 (ethoxy) -Br (bromo) -CH 2 CH 2 CH 3 (propyl) -OCH 2 CH 2 CH 3 (propoxy) -I (iodo) CH 3 CHCH 3 (isopropyl) -OCH 2 CH 2 CH 2 CH 3 (butoxy) -NO 2 (nitro) -CH 2 CH 2 CH 2 CH 3 (butyl) -NH 2 (amino) -C 6 H 5 (phenyl) Examples NO 2 (nitro) i) CH 2 CH 2 CH 3 ii) CH 3 CH CH CH 2 CH 3 (ethyl) CH 3 CH 2 CH CH 3 CH F (fluoro) CH 3 (methyl) 4. The prefix system (excluding mono) must be used to communicate the number of times that a substituent appears on the parent hydrocarbon. Numbers are used to indicate the position of the substituent(s) on the parent chain (e.g. 2,2,3-trimethyl...). 5. If several substituents are present, arrange them in alphabetical order. When alphabetizing the substituents, ignore prefixes that specify the number of a given type of substituent (e.g., di, tri, tetra, etc.). 6. Capital letters must not be used. Place commas between numbers and hyphens between numbers and letters. Numbers must be recorded in ascending order. (eg. 2,2,4 not 4,2,2) Examples CH 3 i) CH 2 CH 2 CH 3 ii) CH 3 CH CH CH 2 CH 3 CH 3 CH 2 CH CH 3 CH CH 3 CH 3 3-methylhexane 3 - ethyl - 2,4 - dimethylpentane Assignment 1. Draw structural diagrams for the following: a) 3 - ethyl -3,4 - dimethylhexane b) 2,3,4 - trimethylpentane c) 5 - ethyl - 3,3 -dimethylheptane 2. Identify mistakes and correct the following: a) 4 - butyl - 6 - ethyl - 2,5 - dimethylnonane b) 4 - ethyl - 2 - methylpentane c) 4,5 - methylhexane CH3 CH3 CH3 — CH — CH2 — CH — CH3 CH3 — CH2 — CH2 — CH — CH — CH3 CH2 CH3 CH3 3. Read chapter 1.1 4. Answer the following questions: P. 14 # 1 & 2 (excluding # 1c & 2d) P. 17 # 1, 2 (a-d), 4 (a-c), 5 (b & c), 6 Structural Isomers Structural isomers are molecules which share the same molecular formula but differ in the way in which the atoms are bonded to one another. Substances that differ in molecular structure are expected to display different properties. Recall: Chemistry is a science which studies substances, their properties, structure, composition, and transformations. Activity: Using expanded molecular formulae and molecular model kits, draw and build the following isomers. a) 3 isomers of pentane (C5H12) b) 5 isomers of hexane (C6H14) c) 9 isomers of heptane (homework - do not build) Answer to (c) heptane 2 - methylhexane 3 - methylhexane 2,2 - dimethylpentane 2,3 - dimethylpentane 2,4 - dimethylpentane 3,3 - dimethylpentane 3 - ethylpentane 2,2,3 - trimethylbutane Functional Groups A functional group is a structural arrangement of atoms that impart particular characteristics to a molecule. During organic reactions such as elimination, substitution, and addition, the skeletal portion of the group remains in tact while the functional or reactive group may undergo some changes. Examples of Functional Groups C=C Multiple bonds C C Intermolecular forces of attraction generally increase because bond polarity increases. C-N C-O C-Br Carbon bonded to highly electronegative Generally speaking, C-Cl atoms. High polarity makes them reactive solubility in water C-F sites. increases, mp & bp increase. C=O C-NH Hydrogen bonds increase polarity and C-OH solubility in water. Alkenes Alkenes are unsaturated hydrocarbons that contain at least one double bond. They are generally colourless, odourless, and are difficult to distinguish from their alkane counter-parts. Since alkenes are non-polar, they are insoluble in water (polar) but they do dissolve in most organic solvents (non-polar). The increased reactivity of alkenes is due to the additional electron density that is supplied by the C=C double bond. Example H H -2H H H H C C H --------> C=C H H H H ethane ethene General Formula: CnH2n Ethene Facts * This planar molecule has a rigid structure where the bond angle is 120/. * Each carbon atom is still involved in creating 4 bonds. * Rotation does not occur about the C=C double bond. * All intramolecular bonds are non-polar therefore alkenes are generally non-polar. * Ethene is used in plastic production (beverage containers, food pouches, motor oil bottles, toys, shrink wrap, plastic bags. * Enzymes produce ethene which causes fruit to soften and develop taste. Cooler temperatures prevent ethene production thus delaying the ripening process during transportation and storage. Ethene can be pumped into food to cause it to ripen. Test for Alkenes 1. Alkenes will cause orange bromine water to turn colourless. 2. Alkenes will cause purple KMnO4 to form a brown precipitate. Basic Alkene Nomenclature Simple alkenes are named by replacing the "ane" ending of the corresponding alkane with “ene”. A number is used to indicate where the double bond begins if the longest chain contains more than 3 carbon atoms. This number must be imbedded in the name before the “ene” suffix with a hyphen on either side. Alkane Alkene Formula ethane ethene C2H4 propane propene C3H6 butane but-1-ene or but-2-ene C4H8 pentane pent-1-ene or pent-2-ene C5H10 hexane hex-1-ene, hex-2-ene, or hex-3-ene C6H12 Structural Diagrams Representing Simple Alkenes propene (n=3) C C C 2 structural isomers of butene (n=4) C C C C C C C C but-1-ene but-2-ene 2 structural isomers of pentene (n=5) C C C C C C C C C C pent-1-ene pent-2-ene 3 structural isomers of hexene (n=6) C C C C C C C C C C C C hex-1-ene hex-2-ene C C C C C C hex-3-ene Naming Alkenes 1. Identify the longest continuous chain containing all double bonds. This chain is given the name of the corresponding alkane. The "ane" suffix is replaced with "ene". 2. The carbon atoms in the longest continuous chain are numbered in such a way so that the first carbon atom in the double bond is given the lowest possible number. This number is imbedded into the name before the “ene” suffix and is surrounded by a hyphen on either side. 3. Numbers are used to indicate the position of the substituent (branched) groups (same as alkanes). 4. Compounds containing more than 1 C = C double bond will require a prefix (e.g. di, tri, tetra) before the "ene" ending. Numbers will be embedded in the middle of the name to communicate where double bonds begin. Each name will begin with the alkane prefix followed by a vowel (e.g. buta, penta, hexa, hepta, nona, or deca). Examples 1. CH 3 1 2 3 4 H 2 C = C — C — CH 3 H H 3-methylbut-1-ene 4 5 CH 2 — CH 3 1 2 3 2. CH 3 — C = C — CH 3 CH 3 2,3-dimethylpent-2-ene 2 1 CH 2 = CH 3 5 4 3 3. CH 3 — C — C NH 2 NO 2 4-amino-3-nitropent-1-ene 4. CH 2 = CH — CH = CH 2 buta-1,3-diene 5. CH 3 CH 3 CH 2 = CH — C = C — C = CH 2 CH 3 2,3,4-trimethylhexa-1,3,5-triene Assignment 1. Read pages 18-23 Stereoisomers Stereoisomers have the same kind and number of atoms bonded in the same order but have different arrangements in space. Consider these 4 isomers of C4H8. H CH2CH3 H CH3 C=C C=C H H H CH3 but-1-ene methylpropene H CH3 H3 C CH3 C=C C=C H3 C H H H trans-but-2-ene cis-but-2-ene Note: The bottom 2 structures are stereoisomers. Assignment 1. Draw and name the cis-trans isomers for C5H10. 2. Why doesn’t but-1-ene have cis-trans isomers ? Use structural diagrams to aid in your explanation. 3. Like other isomers, two cis-trans isomers have the same atomic weight. They yield the same elements when decomposed. How might you distinguish between two such isomers in the lab ? 4. C6H12 has four possible pairs of cis-trans isomers. Draw and name all four pairs. Comparing Alkanes & Alkenes Property Alkanes Alkene saturated unsaturated Strength of weak slightly weaker VDW forces Melting & low (bp of ethane is slightly lower (bp ethene is Boiling Points -89/C) -104/C) Polarity non-polar non-polar Solubility in very low very low water Reactivity low (burn) higher (burn & double bond is a reactive site for addition reactions Alkynes Alkynes are unsaturated hydrocarbons that contain at least 1 triple bond. Example H-C C-H (ethyne) Alkyne Nomenclature Simple alkynes are named by replacing the "ane" suffix of the corresponding alkane with “yne”. Alkane Alkene Structure ethane ethyne H C C H propane propyne H C C CH3 butane but-1-yne H C C CH2 CH3 pentane pent-1-yne H C C CH2 CH2 CH3 Branched alkynes are named in much the same way as alkenes. The longest continuous carbon chain which contains the triple bond is numbered so as to give the first carbon atom in the triple bond the lowest possible number. Substituent groups are named as before. Alkynes are extremely reactive and are not usually found in nature. Most people are familiar with acetylene (ethyne), an alkyne that is used to fuel welding torches. Assignment 1. P. 21 #1 (a-c), 2 (a-c) 2. P. 23 # 1-3 3. P. 27 # 2, 3 (a & b), 4-8 4. Draw structural diagrams for the following: a) 2 - methyl - 3 - nitrobut-1-ene b) 5 - amino - 3,4,6 - trimethyloct-2-ene c) 4,4 - difluoropent-2-yne d) 5 - bromo - 2 - chloro - 6 - iodohept-3-yne e) 4 - isopropyl - 2,5 - dinitrohept-3-ene f) 2,2,5 - trimethylhex-3-yne 5. Name each hydrocarbon. a) CH3 — CH = CH — CH2 — CH — CH2NH2 Cl Br b) CH3 — C— CH2 — CH2 — C = CH — CH3 Br CH2 CH2 — CH3 NO2 c) CH3 — CH — CH — C — CH2 — CH3 I CH — CH2 — CH2 — CH3 CH3 d) CH3 — C — CH2 — C C — CH3 CH3 CH3 CH3 CH2 e) CH3 — CH — CH2 — C — C CH CH2 CH2 — CH3 Cyclic Hydrocarbons Cyclic hydrocarbons occur in a series having the following general formula: CnH2n Like alkanes, simple cycloalkanes are very unreactive and are named by adding the prefix cyclo to the corresponding alkane. Alkane Cycloalkane Formula Line Diagram propane cyclopropane C3H6 butane cyclobutane C4H8 pentane cyclopentane C5H10 hexane cyclohexane C6H12 heptane cycloheptane C7H14  Cyclopropane and cyclobutane are different from other cyclic hydrocarbons because they are very reactive at higher temperatures. Ring strain causes the ring to open thus allowing atoms to be added to the molecule (addition reaction). As the number of carbon atoms on the ring increases, ring strain decreases causing the molecule to become less reactive and more stable. Examples 1. CH2 Ni + H2 ------> CH3 — CH2 — CH3 CH2 CH2 120 oC 2. CH2 high temp. + HBr --------> CH3 — CH2 — CH2 — Br CH2 CH2 Nomenclature 1. Count the number of carbon atoms which are used to make up the ring. This number (n) will be used to determine the name of the corresponding alkane. The prefix “cyclo” is added as a prefix to the alkane. 2. Rings must be numbered in such a way so as to prioritize the following i. priority chart ii. lowest number combination iii. alphabetical order 3. Observe all other nomenclature rules as described before. Examples 1. CH3 2. CH3 CH3CH2 3. H3 C CH3 H3 C CH3 4. CH2CH3 CH3 CH3 CH3 5. CH3CH2 Assignment 1. Draw a condensed structural diagram for each of the following: a) cyclobutene b) 1,2,4 - trimethylcycloheptane c) 2 - ethyl - 3 - propylcyclopentene d) 3 - methylcyclopentene e) 1,3 - diethyl - 2 - methylcyclopentane f) 4 - butyl - 3 - methylcyclohexene g) 1,1- dimethylcyclopentane h) 1,2,3,4,5,6 - hexamethylcyclohexane 2. P. 14 # 1c, 2d 3. P.17 # 2e & f, 4d, 5a 4. P. 21 # 1d, 2d 5. P. 27 #3c Benzene & Aromatic Hydrocarbons Benzene is an aromatic hydrocarbon that is classified as unsaturated due to the presence of shared and delocalized double bonds. Benzene, C6H6 is represented by any of the following structural diagrams; Although benzene is considered to be unsaturated, it is generally unreactive due to its stable structure. Other simple aromatic compounds include; CH3 CH3 CH3 CH3 CH3 CH3 CH3 methylbenzene 1,3-dimethylbenzene 1,2-dimethylbenzene 1,4-dimethylbenzene Assignment 1. Name the following aromatic compounds. Cl F NO2 F NH2 CH3 Br Br CH3 CH2CH3 I CH2CH2CH2CH3 CH3 CH H3C CH3