Chapter 10 – Organic Chemistry CHM1111 Section 04 Instructor: Dr. Jules Carlson Thursday, December 1st

Organic Chemistry There is no way we will be able to cover all of the content of these slides in detail in one lecture. I encourage you all to read your textbook where it is all in greater detail. The plan for this lecture is to give a flavour of the three things important to organic chemistry: Naming the multitude (millions) of organic compounds Understanding the importance (and naming) of different types of isomers Understanding the basics of reaction chemistry and some of the types of reactions that take place

Alkanes, Alkenes, Alkynes Number of Carbons Prefix 1 Meth- 2 Eth- 3 Prop- 4 But- 5 Pent- 6 Hex- 7 Hept- 8 Oct- 9 Non- 10 Dec- Hydrocarbon chains Alkanes – all single bonds (CnH2n+2) Alkenes – one double bond (CnH2n) Alkynes – one triple bond (CnH2n-2)

Alkyl Chains Butane Isobutane Pentane Isopentane Neopentane

Naming Branched-Chain Alkanes Locate the longest continuous chain of carbon atoms. Number the longest chain beginning with the end nearest the substituent. Number the substituent groups accordingly.

Naming Alkenes/Alkynes 2,4-dimethyl-5-heptene 3-ethyl,3-methyl-4-hexyne 1-ethyl,4-methyl-2-cyclohexene

Other Alkyl Groups

Structure of Benzene

 Bonding in Benzene Electron Delocalization

Some Substituents Substituent Group Name -Cl chloro -Br bromo -F fluoro -I iodo -NH2 amino -NO2 nitro -OH hydroxy 2-chloro-2-methyl-3-bromobutane

Ortho, Meta, and Para Substitution Ortho – groups are on adjacent carbons Meta – groups on carbons with one carbon between Para – groups on carbons on opposite sides

Naming Aromatic Compounds

Functional Groups – Halogens Alkyl Halides Alkyl Halides have the structure R-X, where X = F, Cl, Br, I

Functional Groups – Hydroxide Alcohols Ethanol – 2 carbon chain with an alcohol Take name, remove –ne, and add -ol Alcohols can perform H-bonding and alcohols with shorter chains are polar

Secondary and Tertiary Alcohols

Naming Alcohols

Functional Groups with O - Ethers Ethers have the formula R-O-R’ Ethyl isopropyl ether

Functional Groups – Amino Amines

Functional Groups with O - Carbonyl Group Appears in five common functional groups: Aldehydes, Ketones, Carboxylic Acids, Esters and Amides Aldehydes – Carbonyl is on a Terminal Carbon Gains suffix - al Ketones – Carbonyl is on a Central Carbon Gains suffix -one Carboylic Acids – Carbonyl + an alcohol group Gains suffix –oic acid Esters – Carbonyl + an ether group Named first chain –yl, second chain -oate Amides – Carbonyl + an amine group Gains suffix - amide

Aldehydes and Ketones

Carboxylic Acids

Esters

Functional Groups with N- Nitriles Have the formula R≡N Add the suffix -nitrile

Functional Group Summary Chemistry, Canadian Edition ©2010 John Wiley & Sons Canada, Ltd.

Functional Group Summary – cont’d Chemistry, Canadian Edition ©2010 John Wiley & Sons Canada, Ltd.

Stereoisomers Stereochemistry – the study of arrangements of atoms in molecules Isomers – have same atoms but connections are different. (ex. Propanol and Acetone) Stereoisomers – have atoms connected in the same way but differ in arrangement in space Stereroisomer MP (⁰C) BP (⁰C) cis- -81 60 trans- -49 48

The E/Z System List the groups bound directly to the C=C double bond. In this case, they are –H, -Br, -Cl and –CH3. Order them according to priority (higher molecular weight = higher priority) on each C atom. Here, Br > Cl and CH3 > H. Look at the highest priority ones (Br, CH3). If they are cis to one another, it is Z. If they are trans, it is E. This one is therefore (E)-1-bromo-1-chloropropene

Chirality Your hands are enantiomers – they are mirror images of each other

2-pentanol These are therefore enantiomers!

Chirality For a molecule to be chiral, the Carbon must be bonded to 4 different groups There is an R/S system that names compounds based on orientation based on priorities, Place H behind the page, if 1-2 goes right, it is R, 1-2 goes left it is S.

The R/S System 1. Locate the chirality centre, identify the four groups attached to it, and assign priorities to them just as we did for the E/Z configurations of cis–trans stereoisomers. 2. Orient the molecule so that the group having the lowest priority is pointing away from you. 3. Read the other three groups (pointing toward you) from highest to lowest priority. If these are in a clockwise direction, the molecule is the R enantiomer. If they are in the counter-clockwise direction, it is the S enantiomer. Chemistry, Canadian Edition ©2010 John Wiley & Sons Canada, Ltd.

The R/S System The inactive enantiomer of Ibuprofen The groups attached to the chirality centre in increasing priority are - H, -CH3, -C6H4 and COOH. The other three groups from highest to lowest priority are - COOH, -C6H4 and -CH3. These three groups are in a clockwise order, and so this is the (R)-ibuprofen, and the active enantiomer must be (S)-ibuprofen.

Reactions Types of Reactions: Substitution – Replace one atom or group with another Elimination – Remove an atom(s) from the molecule, produces an unsaturation (double bond between C) Addition – Adding atoms to a double bond

Reactions and Electron Density Nucleophile – Reagents seeking a positive charge. They have a negative charge, a lone pair of electrons or both Electrophile – Reagents seeking a negative charge. They have a positive charge or a partial positive charge. For nucleophilic substitution reactions: Textbook talks about 1-step and 2-step mechanisms, rates of reaction, quality of nucleophiles and leaving groups.

Substitution Reactions Some examples…

Elimination Reactions Examples: Chemistry, Canadian Edition ©2010 John Wiley & Sons Canada, Ltd.

More Addition Reactions

Addition Reactions Things get added across a double bond, e.g. by hydrogenation:

Catalysis of Addition Reactions