Organic Compounds Structure & Nomenclature

functional groups

A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions. They establish the identity of a class of compounds and determine its chemical properties. alcohol, aldehyde, ketone, carboxylic acid, ether, ester, amine, amide

Alkyl substituents naming rules

1. Look for alkyl groups coming off the main chain. These are named according to how many carbons they contain, with an ending of -yl added. 2. The name contains the number of the main‐chain carbon atom they are attached to. 3. If there is more than one of the same group, this is indicated by the use of di ( for 2), tri (3), tetra (4), penta (5), etc. 4. The position of the groups is indicated by numbers with commas between them. 5. If there is more than one kind of group, they are named in alphabetical order, e.g. (ethyl before methyl), not taking into account di, tri, tetra, penta prefixes. ie 3‐propylhept‐2‐ene

What are organic compounds?

Compounds that contain both carbon and hydrogen. Organic compounds may also contain other elements (often O, N, S, P or halogens). There are a large number of organic compounds. There are around 81 million organic substances identified, with around 15,000 additional substances added daily.

line formula

Condensed version of the structural formula, written all on one line and demonstrating the relationship of substituent groups in the molecule.

Aldehyde

General Formula: R-CHO Functional Group: -C=O | H Always 1 x H Aldehydes and ketones both contain a carbonyl group -C=O, where the oxygen has a double bond to a C atom. Name ends in -al

Ester

General Formula: R-CO-OR' Functional Group: -C=O | OR' The chemical reaction between an alcohol and a carboxylic acid to form an ester as the main product. alcoxy group RCO2H + R′OH ⇌ RCO2R′ + H2O

Ketone

General Formula: R-CO-R' Functional Group: -C=O | Aldehydes and ketones both contain a carbonyl group -C=O, where the oxygen has a double bond to a C atom. Name ends in -one

Amide

General Formula: R-CONH2 Functional Group: -C=O | NH2 An amide is a derivative of a carboxylic acid where the -OH is replaced by an -NH2, -NHR, or NR2 group

Carboxylic Acid

General Formula: R-COOH Functional Group: -C=O | OH carbonyl group with a bonded alcohol at the terminal highest priority functional group, so will always have the number 1 weak acids, name always ends in acid

Ether

General Formula: R-O-R' Functional Group: -O- Parent molecule is H2O. Removal of both hydrogen atoms from water and replacement by alkyl groups gives an ether. Ethers are mostly not water soluble. R + R1 are alkyl groups which may be the same or different.

Alcohol

General Formula: R-OH Functional Group: -OH Polar Name ends in an "ol"

Amine

General Formula: RNH2 R2NH R3N Functional Group: -N- | These are derivatives of ammonia

long chain/parent

Identify the longest chain present which includes any double bonds or triple bonds (rule is modified if there are functional groups present - not needed for CHEM1090). Number the parent chain starting with the end that reaches a substituent first. If the longest chain is a cycle, then "cyclo" will be added to the name e.g. cyclopentane.

Naming hydrocarbons

Parent: The main chain (longest stretch of C‐atoms containing certain groups) Unsaturation: Double or triple bonds that are present (-ene, -yne, -ane) Substituents: Groups coming off the main chain

Aromatic compounds

a family of cyclic organic compounds whose functional group is a benzene ring Aromatic compounds display resonance, which gives them extra stability. Not actually double and single C‐C bonds, all C‐C bonds identical in benzene. Sometimes shown as a circle. The simplest aromatic compound is benzene C6H6. unsaturated

condensed structural formula

a structural formula that leaves out some bonds and/or atoms; the presence of these atoms or bonds is understood CH3(CH2)2CH3

expanded structural formula

a type of structural formula that shows the arrangement of the atoms by drawing each bond in the hydrocarbon (Lewis diagram)

alcohols have ___ boiling points than alkanes

higher (because of hydrogen bonds [extreme version of dipole-dipole])

molecular formula

shows the types and numbers of atoms combined in a single molecule of a molecular compound C4H10

structural formula shows

the arrangement of bonded atoms CH3CH2CH2CH3