Chemistry 30 – Organic Chemistry – Part 1 To accompany Inquiry into Chemistry PowerPoint Presentation prepared by Robert Schultz robert.schultz@ei.educ.ab.ca

Organic Chemistry – Preparation – VSEPR Recall VSEPR Theory (valence shell electron pair repulson theory) from Chemistry 20 Organic chemistry will involve 3 particular groupings: 0 lone pairs, 4 bonding pairs - tetrahedral H C H H ••

Organic Chemistry – Preparation - VSEPR 0 lone pairs, 3 bonding pairs – trigonal planar 0 lone pairs, 2 bonding pairs - linear H C H O •• O C O ••

Organic Chemistry - Preparation Recall polarity of covalent bonds from Chemistry 20: 2 particular polar bonds important in organic chemistry C – H bonds are virtually non-polar O — H C = O

Organic Chemistry – Preparation – Intermolecular Forces London Dispersion Forces – all moleculars – temporary dipoles – affected by total # of e- and shape Dipole-dipole Forces – polar moleculars Hydrogen Bonding (H covalently bonded to F, O, or N) affect melting point, boiling point, and solubility

Organic Chemistry – 14.1 - Introduction Organic compounds – originally defined to be compounds from living or once-living organisms Wohler, 1828, synthesized urea (an organic compound) from inorganic chemicals Today organic compounds defined to be molecular compounds of carbon – exception: oxides of carbon – CO, CO2

Organic Chemistry – 14.1 - Introduction Most existing compounds are organic! Special things about carbon that allow it to form so many different compounds: • 4 bonding electrons • ability to form single, double, triple bonds with itself • ability to bond with itself in many different configurations

Organic Chemistry – 14.1 - Introduction Classification: organic compounds hydrocarbons C and H only hydrocarbon derivatives C and H along with O, N, and/or halogen atoms aliphatics without aromatics with alkynes – 1 triple bond between C’s – CnH2n-2 alkenes – 1 double bond between C’s – CnH2n alkanes – all single bonds – CnH2n+2

Organic Chemistry – 14.2 - Hydrocarbons Alkanes - saturated hydrocarbons Term saturated used because alkanes have the maximum number of hydrogens General formula: CnH2n+2 butane first 4 alkanes methane ethane propane

Organic Chemistry – 14.2 - Hydrocarbons The unbranched alkanes are a homologous series because they differ by the number of CH2 units in each Alkanes are tetrahedral around each carbon

Organic Chemistry – 14.2 - Hydrocarbons Since carbons and hydrogens can join up in so many ways, structural formulas are used Different types of structural formulas: we won’t use this type 3 3 2 3

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Nomenclature of alkanes: You must learn the following prefixes: # of C’s prefix 1 meth 2 eth 3 prop 4 but 5 pent 6 hex 7 hept 8 oct 9 non 10 dec

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Start naming by finding the longest continuous chain of carbon atoms. Name the long chain using its prefix with an ane ending. Identify branches, and name using their prefix with a yl ending. Number the longest continuous chain from the end closest to the branching and use the numbers like addresses for the branches.

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes These rules will be introduced by the following examples Several additional rules will be presented with the examples

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example 1: CH3 – CH – CH – CH2 – CH2 – CH3 CH3 CH2 - CH3 CH3 – CH – CH – CH2 – CH2 – CH3 Root name: hexane CH3 CH2 - CH3

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example 1: CH3 – CH – CH – CH2 – CH2 – CH3 CH3 CH2 - CH3 CH3 methyl number carbon chain to locate branches 1 2 3 4 5 6 CH3 – CH – CH – CH2 – CH2 – CH3 Root name: hexane CH2 - CH3 ethyl Identify side groups

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Compound name: 3-ethyl-2-methylhexane long chain side group position on long chain Additional rule: list side groups in alphabetical order

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes CH3 – CH – CH – CH – CH3 CH3 Example: CH3 – CH – CH – CH – CH3 CH3 CH3 – CH – CH – CH – CH3 CH3 CH3 – CH – CH – CH – CH3 CH3 No matter how the long chain is selected, the name is the same: 2, 3, 4 - trimethylpentane CH3 – CH – CH – CH – CH3 CH3 Note the tri; use di, tri, tetra, etc, but don’t use them for alphabetical order

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Example: CH3 – CH2 – C – CH3 CH2 – CH3 CH – CH3

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes CH2 – CH3 CH3 – CH2 – C – CH3 CH – CH3 CH2 – CH3 3 – ethyl – 3, 4 – dimethylhexane or 4 – ethyl – 3, 4 - dimethylhexane Which one??? lowest set of numbers

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Doing the reverse process is actually easier – draw your long chain and attach the groups in the addressed spots Start by drawing the long chain without any hydrogens – don’t worry about orientation Add side groups in their addressed spots Add hydrogens (each C gets 4 bonds) Do alkane nomenclature worksheet

Organic Chemistry – 14.2 – Hydrocarbons: Alkanes Physical Properties of Alkanes: All alkanes are non-polar, only intermolecular forces = London Dispersion Forces – boiling point and melting point increase with number of carbons (see chart page 551) KNOW all alkanes are insoluble in water

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Alkenes are hydrocarbons with 1 double bond Note dienes and trienes also exist – we’ll focus on compounds with 1 double bond Alkenes with 1 double bond have the general formula, CnH2n Since they have 2 less hydrogens than corresponding alkanes, they’re called unsaturated hydrocarbons

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Alkene formulas: Alkenes are trigonal planar around the doubly bonded C’s and tetrahedral around the others 3 we won’t use this type

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Nomenclature of alkenes: find longest continuous chain of carbons that contains the double bond – same prefixes as for alkanes add ene to the prefix along with a number to indicate the position of the double bond (for ethene and propene a position number is not needed) number the long chain from the end closest to the double bond (not the branching)

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Example: CH3 – CH2 – CH2 – C = CH2 CH2 CH3 length of long chain containing double bond side-group position of side-group position of double bond CH3 – CH2 – CH2 – C = CH2 CH2 CH3 2 – ethylpent-1-ene

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Do questions 10 – 14 on pages 554-5

Organic Chemistry – 14.2 – Hydrocarbons: Alkenes Physical properties of alkenes: Like alkanes, alkenes are non-polar and are insoluble in water Boiling points are slightly lower than those for alkanes with the same number of carbons Why? Smaller # of electrons, weaker LDF lower boiling point

Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Alkynes are unsaturated hydrocarbons with 1 triple bond General formula CnH2n-2 Alkynes are linear around the triply bonded carbons and tetrahedral around other carbons

Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Alkynes are non-polar aliphatic hydrocarbons like alkanes and alkenes They are insoluble in water

Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Note that alkynes have higher boiling points than alkanes or alkenes Obviously the explanation used for alkenes being lower than alkanes doesn’t apply here Table 14.5, page 557

Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Accepted explanation is that for short chain alkynes, the linear structure around triple bond allows them to come closer together than alkanes or alkenes with same number of carbons, causing stronger London Dispersion Forces

Organic Chemistry – 14.2 – Hydrocarbons: Alkynes Nomenclature of alkynes is identical to that of alkenes, the only exception is the ending: yne, not ene Do Practice Problems 16 and 17 on pages 556 and 557

Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Cyclic analogues exist for alkanes, alkenes, and alkynes General formulas will contain 2 less hydrogens than the open chain hydrocarbons: cycloalkanes CnH2n, cycloalkenes CnH2n-2, cycloalkynes CnH2n-4 Small cycloalkynes don’t exist because of the large bond strain that would exist around the linear triple bond

Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Line structures are commonly used for the ring part of cyclic hydrocarbons Always draw them this way Examples: CH2 cyclopropane: not CH2 CH not cyclobutene:

Organic Chemistry – 14.2 – Hydrocarbons: Cyclics Cyclics will always have names ending with cyclo_____ane or cyclo_____ene Don’t worry about cyclo_____ynes, you will not encounter them, except my favourite one, Consider the following examples to learn how to do the nomenclature for substituted cyclics STOP Name? stopsyne!

Organic Chemistry – 14.2 – Hydrocarbons: Cyclics CH2 – CH3 ethylcyclopentane No numbers needed. Why? CH2 – CH3 Always start at far side of double bond and number clockwise or counter-clockwise towards group 3-ethylcyclopentene CH2 – CH3 CH3 4-ethyl-3-methlycyclopentene As above. This one must be numbered counter-clockwise to give lowest set of numbers, even though 1st group gets a higher number

Organic Chemistry – 14.2 – Hydrocarbons: Cyclics CH2 – CH3 CH3 1-ethyl-2-methylcyclopentane This time the numbering is clockwise since double bond isn’t a factor and when possible lowest number goes on first group Do Practice Problems 18 – 23 page 559 and 560 Do Aliphatics Review WS Quiz coming up!

Organic Chemistry – 14.1 - Introduction Classification: organic compounds hydrocarbons C and H only hydrocarbon derivatives C and H along with O, N, and/or halogen atoms aliphatics without aromatics with finished with aliphatics; aromatics today alkynes – 1 triple bond between C’s – CnH2n-2 alkenes – 1 double bond between C’s – CnH2n alkanes – all single bonds – CnH2n+2

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Aromatics: all contain the grouping Originally this grouping thought to be: Problems: • all bonds found to be equal length • this compound should be very reactive but is actually very stable or

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Today we believe it to be made up of bonds that are neither single nor double but a hybrid of both We draw the structure Its name is benzene Benzene is the root common to all aromatics

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Nomenclature of Aromatics: page 561 Where numbering starts

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Examples: propylbenzene CH2 – CH2 – CH3 CH3 CH2 – CH3 1-ethyl-3-methylbenzene CH3 – CH – CH3 2-phenylpropane

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics Do Practice Problems 24 – 27, page 562 Aromatics WS

Organic Chemistry – 14.2 – Hydrocarbons: Aromatics

Organic Chemistry – 14.3 – Hydrocarbon Derivatives hydrocarbon derivatives C and H along with O, N, and/or halogen atoms alkanes – all single bonds – CnH2n+2 organic compounds hydrocarbons C and H only aliphatics without aromatics with alkynes – 1 triple bond between C’s – CnH2n-2 alkenes – 1 double bond between C’s – CnH2n alcohols R-OH akyl halides R-X carboxylic acids R-C-OH = O esters R1 – C – O – R2

Organic Chemistry – 14.3 – Hydrocarbon Derivatives Hydrocarbon derivatives contain other elements besides C and H; most commonly O, N, or halogen atom Functional group: group of atoms that gives the compound its characteristic properties

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Alcohols – functional group: “-OH” hydroxyl group Common alcohols: table 14.7, page 566 3

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Nomenclature of alcohols Key points – long chain must have “–OH” attached to it Numbering of the long chain starts from the end closest to “-OH” Ending of root is ol

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Example CH3 – CH2 – CH2 CH3 – CH – CH2 – CH2 – OH side group position of side group position of OH length of long chain containing OH* CH3 – CH2 – CH2 CH3 – CH – CH2 – CH2 – OH 3-methylhexan-1-ol * don’t count OH in length of chain

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Example CH2 – CH – CH2 OH length of long chain containing OH’s position of OH’s number of OH’s CH2 – CH – CH2 OH propane - 1, 2, 3 - triol common name of this compound: glycerol Advantages to above name??

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Do Practice Problems 28 – 30 on page 567 Omit 28d, 29c, 30a

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alcohols Physical properties of alcohols Because of the hydrogen bonding between OH groups in adjacent molecules, • alcohols have much higher boiling points than hydrocarbons (1-12 C’s are liquids at SATP) • small alcohols are totally miscible with water, but ……………

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Alkyl halides contain at least 1 halogen atom, (F, Cl, Br, I) Alkyl halides are all synthetic compounds CFC’s (chlorofluorocarbons) are alkyl halides

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Nomenclature of alkyl halides: long chain must be attached to halogen atom(s) identical to nomenclature of hydrocarbons side groups end in o, not yl – fluoro, chloro, bromo, iodo

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Example: CH3 – CH2 – CH – CH – CH – CH3 Br Cl CH3 – CH2 – CH – CH – CH – CH3 Br Cl 2, 4 – dibromo – 3 - chlorohexane

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Alkyl Halides Do Practice Problems 31, 32, page 569 Do Alcohols/Alkyl Halides Nomenclature WS Br Cl 1,4 – dibromo – 2 - chlorocyclohexane

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Carboxylic acids are weak organic acids containing the carboxyl functional group, often written –COOH When carboxylic acids, ionize, the process is: - C – OH , = O R - C – OH , = O R - C – OH(aq) = O R - C – O-(aq) H+(aq) + 

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Common carboxylic acids, acetic acid (active ingredient of vinegar) and citric acid Nomenclature of carboxylic acids: In all carboxylic acids the carboxyl group is at one end of the molecule It is always carbon #1 in the chain

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Example: CH3 – C – CH2 – CH2 – C – OH = O CH2 CH3 CH3 – C – CH2 – CH2 – C – OH = O CH2 CH3 4, 4 – dimethylhexanoic acid note that the carboxyl carbon does get counted in the long chain – it is carbon #1

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Do Practice Problems 33 – 35, page 570

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Carboxylic Acids Physical properties of carboxylic acids: Like alcohols they have hydrogen bonding, but hydrogen bonding at 2 sites, -C=O and –OH This leads to higher boiling points and greater solubility than alcohols with same number of C’s Carboxylic acids with 1-4 C’s are completely miscible in water

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Esters have the general formula: often written RCOOR′ Esters are formed from the reaction of an alcohol and a carboxylic acid; the formation or esterification reaction is the key to naming them R(or H) - C – O – R′ = O

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters R - C – O - H = O R - C – O - R′ = O + H - O - R′ + HOH carboxylic acid alcohol ester water It’s important that when you look at ester, that you’re able to recognize part that came from alcohol and part that came from acid Acid part contains C; alcohol part is bonded directly to O O =

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters General form of name: _______yl _________oate from alcohol from acid

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Examples: acid part: propanoate CH3 – CH2 – C – O – CH3 = O alcohol part: methyl methyl propanoate CH3 – CH2 – CH2 – CH2 – O – C – H = O acid part: methanoate alcohol part: butyl butyl methanoate

Organic Chemistry – 14.4 – Refining and Using Organic Compounds Do questions 37 and 38 page 572

Organic Chemistry – 14.3 – Hydrocarbon Derivatives: Esters Physical properties of esters: fruity odour in some cases polar but lack of OH bond means no hydrogen bonding, so lower boiling points than alcohols and carboxylic acids esters with few carbons are polar enough to be soluble in water

Organic Chemistry – 14.3 – Hydrocarbon Derivatives Structural isomers: compounds with same molecular formula but different structural formulas

Organic Chemistry – 14.4 – Refining and Using Organic Compounds Petroleum: mixture of hydrocarbons (primarily alkanes and alkenes) found in natural gas, crude oil, and bitumen (from tar sands) Petrochemicals: hydrocarbon materials from petroleum used to produce plastics and other synthetic materials

Organic Chemistry – 14.4 – Refining and Using Organic Compounds Fractional distillation: a means of separating petroleum components based on differing boiling points

Organic Chemistry – 14.4 – Refining and Using Organic Compounds Read and discuss page 578 regarding fractional distillation Fractional distillation is a physical process; mixture is separated into fragments with a small range of boiling points – there is no chemical change in the fractions

Organic Chemistry – 14.4 – Refining and Using Organic Compounds Next stages of petroleum refining are chemical processes: • cracking – breaks carbon-carbon bonds • reforming – forms carbon-carbon bonds alkylation (special case of reforming) forms 2,2,4-trimethylpentane from smaller hydrocarbons Both of these can be divided into many subgroups Read page 579-80 and page 581

Organic Chemistry – 14.4 – Refining and Using Organic Compounds

Organic Chemistry – 14.4 – Refining and Using Organic Compounds