Copyright © Houghton Mifflin Company. All rights reserved.14 | 1 Organic Chemistry - Introduction Organic chemistry is the study of carbon compounds. It’s

Copyright © Houghton Mifflin Company. All rights reserved. 14 | 1

Organic Chemistry - Introduction

• Organic chemistry is the study of carbon compounds. It’s the most versatile element on the table!

• Animals, plants, and other forms of life consist of organic compounds.– Nucleic acids, proteins, fats,

carbohydrates, enzymes, vitamins, and hormones are all organic compounds.

Intro


Bonding in Organic Compounds• Besides carbon, the most common elements in

organic compounds are hydrogen, oxygen, nitrogen, sulfur, and the halogens.

• All of the preceding elements are non-metals, therefore organic compounds have covalent bonding.

• Any structural formula that obeys the bonding rules in the following table probably represents a possible compound.– A drawn structure that breaks the bonding rules is

unlikely to exist.

Section 14.1

Copyright © Houghton Mifflin Company. All rights reserved. 14 | 3Section 14.1


• Two structural formulas are shown above. Which on does not represent a real compound?

• In structure (a) each H and halogen has one bond, each C has four bonds, and each O has two bonds.

• In structure (b) the O can only have 2 bonds.

Section 14.1


• The structural formula above appears in a recent chemistry book. Check the number of bonds to each atom and determine whether any bonding rules are violated.

Section 14.1


Identifying Incorrect Structural FormulasConfidence Exercise

This is not a valid structure for caffeine!

O should have two bonds, C should have 4

bonds

Each N should have 3 bonds

Each C should have 4

bonds

Section 14.1


Hydrocarbons

• Hydrocarbons are the most simple organic compounds.

• Hydrocarbons contain only carbon (C) and hydrogen. (H)

• There are two major categories of hydrocarbons Aliphatic (Without Benzene) and Aromatic (With Benzene)

Section 14.2


Aliphatic Hydrocarbons

• Aliphatic hydrocarbons are straight chain hydrocarbons without benzene rings. (Well talk more about those later.

• Four major divisions:– Alkanes

– Cycloalkanes

– Alkenes

– Alkynes

Section 14.3


Alkanes• Alkanes are hydrocarbons that contain

only single bonds.• Alkanes are said to be saturated

hydrocarbons– The have the maximum number of

hydrogen atoms possible.

• Alkane general formula CnH(2n + 2)

• The names of alkanes all end in “-ane.”

Section 14.3


Alkanes – What are they good for?

• Methane = primary component of natural gas• Propane & Butane = primary component of

bottled gas• Gasoline = pentane to decane• Kerosene = alkanes with n = 10 to 16• Alkanes with n > 16 diesel fuel, fuel oil,

petroleum jelly, paraffin wax, lubricating oil, and asphalt

• Alkanes are found in paints, plastics, drugs, detergents, insecticides, and cosmetics.

Section 14.3

A New Naming System!!!The prefix for an alkane is important. It tells us

how many carbons are part of the molecule.

1 Carbon = “Meth” 6 Carbons = “Hex”

2 Carbons = “Eth” 7 Carbons = “Hept”

3 Carbons = “Prop” 8 Carbons = “Oct”

4 Carbons = “But” 9 Carbons = “Non”

5 Carbons = “Pent” 10 Carbons = “Dec”



How to draw an Alkane – 4 ways!

Section 14.3

Structural formula – a graphical representation of the way atoms are connected

Condensed structural formula – save time/space and are convenient. Write like a formula.

Ball-and-Stick models – 3D models that can be built by students

Line Angle formula– fast to draw. All “bends” and “ends” are carbons. Hydrogen is assumed.


Models of Three Alkanes

Section 14.3

Line Formula

Structural Formula

Condensed Formula

Ball and Stick Models

• #1) Draw the structural formula for propane. (Think Lewis Dot w/o the dots)

• #2) Draw the condensed structural formula for butane. (Think Chemical formulas)

Copyright © Houghton Mifflin Company. All rights reserved.

Practice – Naming!

• #3) Name this Alkane:

CH3(CH2)4CH3

• #4) Name this Alkane


Copyright © Houghton Mifflin Company. All rights reserved. 14 | 16Section 14.3


Isomers• Molecules that have the same molecular

formula but different structural formulas

• In the case of many alkanes there is more than one way to arrange the atoms.

• For example butane and isobutane.

• Both of these alkanes have the molecular formula of C4H10 but their structural formula and arrangement is quite different.

Section 14.3


Butane Isobutane

C4H10

Structural Formula

Ball-and-Stick Model

Section 14.3

C4H10Structural Formula

Ball-and-Stick

Model

SO, We can have the same formula but have different names? AWESOME!

• I know it can seem a bit overwhelming, but no worries. There is a system of naming that allows us to determine how to name all Organic Compounds.

• IUPAC – International Union of Pure and Applied Chemistry– A standardized way to write chemical

compounds.


• What is different and unique about this molecule?

• It’s called a branched Alkane! How many total carbons make it up?

• But it’s not simply hexane. The Carbons are not all in a straight line. This is an example of a “methyl” group. A 1 carbon “side chain” off of a 5 carbon “backbone”



Alkyl Groups

• Alkyl group contains one less hydrogen than the corresponding alkane.

• Think of it as adding a CH3 group to a carbon.

• In naming this group the “-ane” is dropped and “-yl” is added.

• For example, methane becomes methyl.

• Ethane becomes ethyl.

Section 14.3


Alkyl GroupThese groups do not exist independently but occurs

bonded to another atom or molecule.

Section 14.3


IUPAC System For Naming Alkanes1) Compound is named for the longest continuous

chain of C atoms.

2) Find something “interesting” that attaches to the chain of carbon. Number the carbons so that the “interesting” thing has the lowest number possible.

3) If there is more than one interesting thing, list them in order alphabetically.

4) If there is more than one of the same interesting thing, include prefixes – di, tri, tetra, ect…. (These are not Alphabetical!)

Section 14.3


An Example to Consider

• Start by finding the longest continuous chain of Carbon atoms. This is going to be a __________.

• Is there anything interesting attached? Number the carbons so that it has the lowest number possible.

• What is the interesting thing? And what number carbon is it on?

Section 14.3

2-methylpentane

Another Example to ConsiderFirst draw and then name the following molecule:

CH3CH2CH(CH2CH3)CH2CH3


What’s the longest carbon chain?

What’s the interesting thing?

What’s the lowest possible number it can be on?

3-ethylpropane


Substituents involving Halogens

Section 14.3

These elements are just like hydrocarbon side chains. They can be attached to any carbon.

Practice Problem1) Draw the complete structural

formula for 1-bromopentane.

2) Draw the line formula for 1-chloro-2-fluorobutane


Two of the same thing!


F

F

• How would you name this compound?• What’s the longest C chain?• What are the interesting things?• Humm, they’re the same thing, so this is when we prefixes! (Difluoro) but where are they?

1,4-difluoropentane


Practice Problem• Draw the structural formula for 2,3-dimethylhexane.

• Note that the end name is hexane .• Draw a continuous chain of six carbon (C) atoms,

with four bonds around each.• Number the carbons and put two different methyl

groups on the correct carbons.

Section 14.3


Drawing a Structure from a NameConfidence Exercise

• Draw the structural formula for 2,2,4-trimethylpentane.

• Note that the end name is pentane .

• Draw a continuous chain of five carbon (C) atoms, with four bonds around each.

Section 14.3


Drawing a Structure from a NameConfidence Exercise (cont.)

• Number the C atoms from right to left.

• Attach two methyl groups (CH3--) to carbon number 2 and one to number 4.

Section 14.3


2,2,4-trimethylpentane Ball-and-Stick Model

Copyright © Bobby H. Bammel. All rights reserved.

Section 14.3


Review of the Rules1) Compound is named for the longest continuous

chain of C atoms.

2) Find something “interesting” that attaches to the chain of carbon. Number the carbons so that the “interesting” thing has the lowest number possible.

3) If there is more than one interesting thing, list them in order alphabetically.

4) If there is more than one of the same interesting thing, include prefixes – di, tri, tetra, ect…. (These are not alphabetical!)

Section 14.3

Practice Problem


1) Draw the correct condensed formula for 2-bromo-3-ethylbutane.

2) Draw the correct line structure for 2,3-difluoro-1,2,5-trimethaloctane.

Practice Problem


1) Name this molecule:

2) Name this molecule:

Br

ClBr

Cycloalkanes


Documents

Copyright © Houghton Mifflin Company. All rights reserved.14 | 1 Organic Chemistry - Introduction Organic chemistry is the study of carbon compounds. It’s