Organic chemistry is the study of the properties of the compounds of carbon. Just about everything...

Organic chemistry is the study of the properties of the compounds of carbon.

Just about everything in this world has carbon, C, in it!

Copyright © Houghton Mifflin Company. All rights reserved. 7 | 2

Learning Objectives

a. Organic molecules form the basis for life and include many natural products with medicinal properties.

b. After the structure of a biologically active compound is determined, organic chemists can often synthesize the compound, as well as new derivatives with more powerful activities.


Learning Objectives (cont)

c. Most organic compounds contain a hydrocarbon framework containing chains of carbon atoms and bonded hydrogen atoms (“hydrocarbons”).

d. Hydrocarbons are classified according to types of carbon-carbon bonds. Alkanes contain only single bonds, alkenes contain at least one double bond, alkynes contain at least one triple bond, and aromatics are rings that contain alternating single and double bonds.


Learning Objectives (cont)

e. Adding different atoms or groups of atoms (functional groups) to a hydrocarbon results in new classes of compounds with distinctive chemical properties.

f. The geometric arrangement of atoms within an organic compound determines its activity.

g. Two mirror-image molecules (enantiomers) with the same chemical formula and connections of the atoms can have different biological activities.


• General Properties of Organic Compounds a. Review of Carbon

1. Carbon has four electrons in its outer shell and therefore can form four covalent bonds.

b. Polarity 1. Organic molecules contain many nonpolar C-H bonds

and are therefore generally hydrophobic.


Three waysin which carbon can fulfill its octet


Effect of differences in electronegativity on charge distribution


• General Properties of Organic Compoundsc. Intermolecular Forces

1. Small hydrocarbons interact through relatively weak London forces and therefore tend to be gases at room temperature.


Melting and BoilingPoints of Hydrocarbons


• General Properties of Organic Compoundsc. Intermolecular Forces

3. Large hydrocarbons and those containing bonded polar atoms are often liquids or solids at room temperature.

4. Organic molecules containing bonded polar atoms are generally more water soluble than those containing only carbon and hydrogen. (Like dissolves like.)


Water Solubility ofAlcohols vs. Alkanes

OH groups can make a molecule, with less than 8 carbons, water soluble


• Natural Products a. Some compounds found in nature (natural

products) have interesting properties, such as medicinal activity.

b. Once the structure of a natural product is determined, chemists may seek to synthesize the compound in the laboratory.

c. Parent compounds, like salicin, serve as the structural basis for new synthetic molecules (derivatives or analogues).


Synthesis of Derivatives

The willow tree, source of the active ingredient of aspirin


The Pacificyew tree, source of taxol

A molecule with powerfulAnticancer activity!


• Types of Hydrocarbons a. Alkanes: contain only single carbon-carbon

bonds

b. Alkenes: contain at least one double carbon-carbon bond

c. Alkynes: contain at least one triple carbon-carbon bond

d. Aromatics: ringed hydrocarbons with alternating single and double bonds between carbons.


Examples of Straight-Chain Alkanes


Reduction ofhydrocarbons vs. oxidation


Reactivity of Alkanes

Hydrocarbon + O2 carbon dioxide + water + heat energy

Ex. CH4 + 2O2 CO2 + 2H2OHeat released is 802 kJ/molof methane

Effect of partially oxidizing a hydrocarbon, let’s look at the combustion reaction of CH3OH (methanol), in which 1 H has been replaced by an –OH group.

2CH3OH + 3O2 2CO2 + 4H2O Heat released is 640 kJ/molof methanol

(1.5 moles of O2 required to with 1 mole of CH3OH!)


These reactions illustrates two important principles.

1st, the more reduced a molecule, the more energy is released during oxidation on a molar basis.

Methane is fully reduced and gives off more energy during combustion than methanol.

2nd, the number of oxygen molecules required to react with a fuel molecule gives an estimate of how much energy is available.

More highly reduced molecules require more oxygen during combustion and produce more energy.


Examples of cycloalkanes

CyclopentaneC5H10


The simplest alkene, ethylene


Saturated fats contain threealkane chains, unsaturated fats three alkene chains


Cis and trans refer todifferent geometries in two isomers


Trans Fatty Acidsin Some Common Food Products


The formation oftrans double bonds, hydrogenation

Polymerization: white plastic water bottles

Credit: Courtesy of Nalgene

monomers


The simplest alkyne, acetylene


Benzene Naphthalene, in mothballs

Anthracene, in insecticides and woodpreservatives

Aromatics Compounds, Polycyclic Aromatic Hydrocarbons (PAH’s)


Bioaccumulation ofPolycyclic Aromatic Hydrocarbons

A process by which chemical contaminationincreases within organismshigher up the food chain.


• Functional Groups are groups of atoms that

contribute to the properties of an organic compound a. Organic Halides ex. CH3-X (X = Cl, Br, I, or F)

b. Oxygen-Containing Functional Groups1. Ethers

2. Aldehydes

3. Ketones

4. Carboxylic Acids

5. Esters


• Functional Groups

• Nitrogen-Containing Functional Groups1. Amines

2. Amides


Alcohols and Ethers

An alcohol contains the hydroxyl (-OH) functional group.

In an ether, an oxygen atom is bonded to two carbon atoms.

–C–O–C– .

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings


Aldehydes and Ketones

An aldehyde contains a carbonyl group (C=O), which is a carbon atom with a double bond to an oxygen atom.

In a ketone, the carbon of the carbonyl group is attached to two other carbon atoms.



Carboxylic Acids and Esters

Carboxylic acids contain the carboxyl group, which is a carbonyl group attached to a hydroxyl group.

O ║

— C—OH

An ester contains the carboxyl group between carbon atoms.



Amines and Amides

In amines, the functional group is a nitrogen atom.

|

—N —

In amides, the hydroxyl group of a carboxylic acid is replaced by a nitrogen group.



Functional Groups


Functional Groups Cont.


Learning Check

Classify each of the following as: alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine or amide.

1) CH3─CH2─CH2─OH

2) CH3─O─CH2─CH3

3) CH3─CH2─NH2

O O ║ ║

4) CH3─C─OH 5) CH3─C─O─CH3


Solution

1) CH3─CH2─CH2─OH alcohol

2) CH3─O─CH2─CH3 ether

3) CH3─CH2─NH2 amine

O O ║ ║ 4) CH3─C─OH 5) CH3─C─O─CH3 carboxylic acid ester

Polymerization of Teflon

Teflon frying pan

Credit: Royalty Free/Alamy

ProblematicOrganic Halides Are No Longer Widely

Used

Examples of Polyhydroxy Alcohols

Examples of Phenols

Examples of Aldehydes

Acetone (A Ketone) is producedduring normal metabolism of fats

A common household Product: nail polish remover.

Acetone can be producedduringmetabolismof fats, particularly in casesof starvation or serious diabetes.

Examples of Carboxylic Acids


• Isomers a. Isomers have the same chemical formula but

different arrangements of atoms.

b. One type of isomers is a pair of enantiomers, molecules that are “handed”.

c. Enantiomers often have different biological activities.

Ex. Ethanol (C2H5O) vs. dimethyl ether or Octane (C8H18) vs isooctane


Enantiomers

Enantiomers are like a pairof gloves: similar shapes thathave “handedness” and areNonsuperimposable

R vs S enantiomers


Key Words

• Organic chemistry• Hydrophobic• Parent compound• Derivative/analogue• Hydrocarbons• Alkanes• Alkenes• Alkynes

• Aromatic• Saturated• Cycloalkanes• Unsaturated• Cis isomer• Trans isomer• Polymer• Monomer

Organic chemistry is the study of the properties of the compounds of carbon. Just about everything...

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