LECTURE MATERIAL FOR -SATURATED HYDROCARBONS - ALKANES. CHAPTERS 3, 4, 5, AND 10 COVER THIS MATERIAL. BE SURE TO DO THE QUIZZES AND PRETESTS RELEVANT FOR THIS.

USE THE BACK BUTTON TO RETURN TO THIS SPOT

LINK TO ALKANES

LINK TO RING ALKANES, CYCLOALKANES, ALICYCLIC

LINK TO HALOGENATED ALKANES

TO VIEW THE STRUCTURAL FORMULAS OF MANY -IF NOT ALL OF THE FOLLOWING-

USE THE LINK TO CABRILLO LIBRARY OF MOLECULES

YOU WILL NEED TO DOWNLOAD A PLUGIN CALLED CHIME TO VIEW THE MOLECULES. THE CD THAT COMES WITH THE TEXT HAS THIS PLUGIN ON IT. THE QUICKTIME MOVES ARE MOST EXCELLENT FOR LEARNING IMPORTANT MECHANISMS. HIGHLY RECOMMENDED!

I RECOMMEND USING THE "OLD VERSION"

REMEMBER YOU DO NOT HAVE TO LOOK AT THESE MOLECULES IF YOU DO NOT HAVE THE TIME.

CABRILLO LIBRARY OF MOLECULES

AND CHECK OUT THE MANY MOLECULES IN THE TABLE OF CONTENTS.

CARBON:THE ELEMENT OF ORGANIC CHEMISTRY .

Organic compounds are compounds based mostly on the element carbon and a very few other elements such as hydrogen, oxygen, nitrogen , halogens, and phosphorus.

Until 1828 it was thought that a special force called 'vitalism' was required to synthesize the chemicals in living organisms. Then in an accidental or serendepitous discovery, Frederich Woehler was able to make urea from the inorganic compound ammonium cyanate by heating.

Now urea is the major end product of nitrogen metabolism in man. We are ureotelic organisms. Hence a vital component of our metabolism was prepared by simple heating from a compound never found in living organisms.

This initiated a revolution in science which competely changed the way we live.

INORGANIC AND ORGANIC COMPOUNDS COMPARED .

A comparison of the carbon-based organic compounds versus the non-carbon based inorganic compounds, is essentially a comparison of covalent compounds to ionic compounds.

11.3 BONDING CHARACTERISTICS AND ISOMERISM . [ PAGE 326 ]

Carbon owes its unigue position in the chemistry of living organisms to its ability to form multiple links to itself resulting in long chains of carbon atoms and to its ability to bond to other elements such as hydrogen, nitrogen, oxygen, phosphorus, sulfur, and the halogens such as chlorine and bromine.

The arrangement of electrons in carbon 1s² 2s² 2p² and its common hybridization pattern sp³

The two different arrangements of the colored blocks can be viewed as a model for two isomers and the blocks are the constituent atoms in a molecule.

The transformation of the inorganic ammonium cyanate into the organic urea is also an example of isomerism as the two compounds have the same number and kinds of atoms but with different arrangements. They are isomers. [ from the Greek iso = same and meros = parts ].

ALKANES

There are many other examples of the concept of isomerism that we will be examining in this course, here follows a sample of this that we will be dealing with later.

NOTE HOW THE ISOMERS GIVEN ABOVE ILLUSTRATE THE RULES GIVEN BELOW - YOU NEED NOT MEMORIZE THE BP'S BUT YOU MUST KNOW THE GENERAL TRENDS.

FUNCTIONAL GROUPS AND FUNCTION AL GROUP ISOMERISM

Here are two examples of functional group isomerism. These two molecules have the same molecular formula, C₂H₆O. But have different physical properties. They are isomers.

image courtesy of Cabrillo College, C4 Project

ETHYL ALCOHOL OR ETHANOL

BOILING POINT 78

HYDROGEN BONDING AS WELL AS VAN DER WAALS & DIPOLE FORCES PRESENT

image courtesy of Cabrillo College, C4 Project

DIMETHYL ETHER

BOILING POINT -24

VAN DER WAALS & DIPOLE FORCES PRESENT

Alkanes have the general formula C_NH_[2N+2]. Alkanes are known as SATURATED hydrocarbons because they contain the elements carbon and hydrogen and have their valence saturated with hydrogen atoms. The word saturated has some important health implications that we shall examine in a later chapter.

Alkanes are also called paraffins from Latin words meaning 'unreactive'. Food grade paraffin is used in coating fruits and vegetables. Also as a covering for homemade jelly and in making chocolate.

Hydrocarbon sections of molecules are classified as non-polar or hydrophobic [ water hating ] and they are insoluble in water.

The section to the left with the red lines is a hydrocarbon part of the molecule and it will be non-polar and hydrophobic.

Non-Hydrocarbon sections of molecules such as -NH₂ OR -OH are classified as polar or hydrophilic [ water loving ] and they are soluble in water.

The section to the right with thebluelines is a non-hydrocarbon part of the molecule and it will be polar and hydrophilic.

ALKANE STRUCTURAL FORMULAS.

Hydrocarbons are organic or carbon- based molecules that contain carbon and hydrogen only.

They are usually classified according to the types of chemical bonds or functional groups contained therein.

There is a listing of these functional groups in the text. SEE INDEX IN TEXT FOR PAGE.

Our main tasks in this section are:

1. To study the properties and uses of the functional group.

2. To understand their naming system.

3. To learn about their reactions.

The first of these functional groups is the alkanes.

image courtesy of Cabrillo College, C4 Project

ETHANE

HERE IS A LINK TO A WEB SITE THAT HAS A MANY INTERESTING VIEWS OF ALKANES -YOU CAN ROTATE THEM & DO OTHER MANUEVERS.

NOMENCLATURE OF ALKANES

MEMORIZE THESE ALKYL GROUPS! THE BEST METHOD IS TO USE FLASHCARDS WITH THE FORMULA ON ONE SIDE AND THE NAME ON THE OTHER.

ALKANE NAME	ALKYL GROUP OR RADICAL NAME	ALKYL GROUP OR RADICAL FORMULA
METHANE	METHYL	CH3-
ETHANE	ETHYL	CH3CH2-
PROPANE	n-PROPYL	CH3CH2CH2-
PROPANE	ISOPROPYL

FOR MORE ALKYL RADICALS AND ALKANES - SEE TEXT IN CHAPTER 3 - MEMORIZE THE ALKANES FROM C1 TO C10 AND THE RADICALS FROM C1 THROUGH C5.

There are two tasks involving the naming or nomenclature of organic compounds.

1. Given the structural formula, write out the complete name according to the IUPAC or systematic system rules or the common system of nomenclature.

2. Given the name, write out the complete structural formula obeying all of the rules of valency.

Here are some examples, and the text has many more good examples in CHAPTER 3.

CYCLOALKANES

ALICYLIC COMPOUNDS OR RING COMPOUNDS OR CYCLOALKANES

PHYSICAL PROPERITES OF ALICYCLIC OR RING OR CYCLOALKANES

GEOMETRY OR CIS-TRANS ISOMERISM OF CYCLOALKANES.

Here is a link to the preceding section on isomerism

There is a type of isomerism that is found in cycloalkanes and in olefins or alkenes in which molecules that have the same atoms in the chain and the same substituens on the chain are yet different or isomers. Here the difference originates in the ARRANGEMENT OF THE ATOMS IN SPACE. This is called stereoisomerism and the isomers are stereoisomers.

SEE TEXT IN CHAPTER 3-8 FOR MORE EXAMPLES AND DRAWINGS.

PHYSICAL PROPERITES OF CYCLOALKANES

CHLORINATED HYDROCARBONS- THIS TOPIC IS COVERED IN SEVERAL PLACES IN THE TEXT 5-3 AN 10 -1, 2, 3

HERE IS A LINK TO A WEB SITE THAT HAS A REVIEW OF SOME ASPECTS OF CHLORINATED HYDROCARBONS.

IUPAC

These are compounds in which one or more of the hydrogen atoms in a hydrocarbon has been replaced with chlorine [ or bromine ]. Chlorine and bromine are members of GROUP VIIA in the periodic table whose family name is the halogens.

These compounds found wide use as solvents, anesthetics, refrigerants, and pesticides. Their use has been restricted in recent years because of concern for their toxicity as several appear to be carcinogens [cause cancer] and their hepatotoxicity [ toxic to the liver ].

REACTIONS OF CYCLIC OR RING ALKANES ALSO CALLED ALICYCLIC ALKANES

These alicyclic alkanes undergo reactons with dihydrogen gas and a metal caltalyst if the ring is strained. That is there is a significant difference between the internal dihedral angles in the alicyclic compound and the normal tetrahedral bond angle for the sp³ hybridized carbon atom.

THIS IS WELL PRESENTED IN CHAPTER 4 - SECTION 4, 5, 6

FOR THE STEREOCHEMISTRY OF ALKANES SEE CHAPTER 4 - SECTION 1, 2, 3 BE SURE TO PERUSE THE PICTURES AND ENERGY DIAGRAMS PRESENTED THEREIN.

BE SURE DO TO THE PROBLEMS IN THE NOTES & EXERCISE TEXT ON PAGES 97, 99, & 101. THE ANSWERS ARE GIVEN FOR MOST OF THESE. SEE ALSO THE FOLLOWING LINK.

LECTURE MATERIALS ALKANE CONFORMATIONS

SOME USEFUL TERMS

Answers to Problems

1.   Return     2.   COMPOUND B   Return 3.   Give the best name for the following alkane . c. 2,2-dimethylpropane Return      4. Return   5.   The name of the following cycloalkane is: b. methylcyclopropane Return   6.The best name for the following cycloalkane is:   c. trans-1,2-dimethylcyclopropane   Return 7. b. CH3Cl Return 8. Select the appropriate product for the following reaction: a. CH2Cl2 CH2Cl2 is the formula for methylene chloride. This was once widely used as a paint remover. Return   9.The formula for dichloromethane or methylene chloride is b. CH2CL2   Return 10.Chlorinated hydrocarbons such as methylene dichloride are toxic to the LIVER. Return