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. Copyright © Houghton Mifflin Company. All rights reserved. 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.1

Copyright © Houghton Mifflin Company. All rights reserved. Section 14.1

In structure (b) the O can only have 2 bonds. 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.1

The structural formula above appears in a recent chemistry book 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.1

Identifying Incorrect Structural Formulas Confidence Exercise O should have two bonds, C should have 4 bonds Each C should have 4 bonds Each N should have 3 bonds This is not a valid structure for caffeine! Copyright © Houghton Mifflin Company. All rights reserved. Section 14.1

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) Copyright © Houghton Mifflin Company. All rights reserved. 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 Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

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.” Copyright © Houghton Mifflin Company. All rights reserved. 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. Copyright © Houghton Mifflin Company. All rights reserved. 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” Copyright © Houghton Mifflin Company. All rights reserved.

How to draw an Alkane – 4 ways! Structural formula – a graphical representation of the way atoms are connected Condensed structural formula – save time/space and are convenient. Write like a formula. Line Angle formula– fast to draw. All “bends” and “ends” are carbons. Hydrogen is assumed. Ball-and-Stick models – 3D models that can be built by students Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Models of Three Alkanes Structural Formula Condensed Formula Ball and Stick Models Line Formula Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

#1) Draw the structural formula for propane #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 Copyright © Houghton Mifflin Company. All rights reserved.

Copyright © Houghton Mifflin Company. All rights reserved. Section 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Butane Isobutane C4H10 Structural Formula Ball-and-Stick Model C4H10 Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

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. Copyright © Houghton Mifflin Company. All rights reserved.

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” Copyright © Houghton Mifflin Company. All rights reserved.

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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Alkyl Group These groups do not exist independently but occurs bonded to another atom or molecule. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

IUPAC System For Naming Alkanes 1) 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!) Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

An Example to Consider 2-methylpentane 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? Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Another Example to Consider First draw and then name the following molecule: CH3CH2CH(CH2CH3)CH2CH3 3-ethylpropane What’s the longest carbon chain? What’s the interesting thing? What’s the lowest possible number it can be on? Copyright © Houghton Mifflin Company. All rights reserved.

Substituents involving Halogens These elements are just like hydrocarbon side chains. They can be attached to any carbon. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Practice Problem 1) Draw the complete structural formula for 1-bromopentane. 2) Draw the line formula for 1-chloro-2-fluorobutane Copyright © Houghton Mifflin Company. All rights reserved.

Two of the same thing! F 1,4-difluoropentane 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? Copyright © Houghton Mifflin Company. All rights reserved.

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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name Confidence 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. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Drawing a Structure from a Name Confidence Exercise (cont.) Number the C atoms from right to left. Attach two methyl groups (CH3--) to carbon number 2 and one to number 4. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

2,2,4-trimethylpentane Ball-and-Stick Model Copyright © Bobby H. Bammel. All rights reserved. Copyright © Houghton Mifflin Company. All rights reserved. Section 14.3

Review of the Rules 1) 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!) Copyright © Houghton Mifflin Company. All rights reserved. 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. Copyright © Houghton Mifflin Company. All rights reserved.

Practice Problem 1) Name this molecule: 2) Name this molecule: Br Cl Copyright © Houghton Mifflin Company. All rights reserved.

Cycloalkanes Copyright © Houghton Mifflin Company. All rights reserved.