Organic Chemistry CSEC

Organic Chemistry

Presentation

CSEC Chemistry by Anne Tindale Chapters 14-17and CSEC Chemistry by Naresh Birju Chapters 14-17

"Organic Chemistry is the study of compounds which contain carbon, known as organic compounds. Organic compounds are the basis of all living things. All organic compounds contain carbon atoms. They usually contain hydrogen atoms and may contain other atoms e.g oxygen, nitrogen, or halogen atoms"

Sources: CSEC Chemistry by Anne TindaleChemistry for CSEC Study Guide CSEC Chemistry by Naresh Birju

Sources of hydrocarbons

Hydrocarbons are compounds made of hydrogen and carbon only.Refer to CSEC Chemisry by Anne Tindale/Naresh Birju Chapter 15

There are two (2) main natural sources of hydrocarbons:natural gas and petroleum

Petroleum/Crude Oil

Natural gas

This is a thick liquid mixture of branched, unbranched and ring hydrocarbons in which some natural gas is also dissolved. It is a yellow to black oily liquid found in the earth. Click here for more.

This mainly consists of methane gas, CH4, which accounts for about 70% to 80% of all the gases present. It also contains smaller amounts of ethane, propane and butane.Click here for more.

Fractional distillation of crude oil/petroleum

Refer to page 134 of Chapter 15 of CSEC Chemistry by Anne Tindale or pages 254-255 of Chapter 15 CSEC Chemistry by Naresh Birju . Click here for more.

VIDEO

Here is another video that details the different fractions and their uses

Cracking

Some fractions from the distillation of petroleum are more useful than others. There is a higher demand for some of the smaller fractions like gasoline so cracking is one method that is used to supply more of these fractions. Click here for more

Introduction to Organic Chemistry

CSEC Chemistry by Anne Tindale /CSEC Chemistry by Naresh Birju Chapter 14

BONDING IN ORGANIC COMPOUNDSCarbon has 4 valence electrons and forms 4 covalent bonds with other carbon atoms or atoms of other elements

FORMULAE OF ORGANIC COMPOUNDSThis includes the molecular formula, the (fully) displayed structural formula and the condensed structural formula

Click above to see more

STRUCTURE OF ORGANIC MOLECULESThe simplest organic molecule has two parts: the hydrocarbon part and the functional group

Click above to see more

Click above to see more

Homologous series

A group of organic compounds which all possess the same functional group, can be represented by a general formula and have particular characteristics. Click here for more

VIDEO SUMMARY OF PREVIOUS TOPICS

Here is a video from Terry David which summarizes all that was said before on the topics: Natural Sources of hydrocarbons and Introduction to Organic Chemistry

ALKANES

Alkanes are saturated hydrocarbonsGeneral formula Cn H2n+2 Alkanes with 1 to 4 carbon atoms are gases at room temperature, 5 to 16 carbon atoms are liquids and those with 17 or more carbon atoms are solids. Alkanes are relatively unreactive because the carbon–carbon single bonds in their molecules are strong..

ALKANES

Substitution/Halogenation reaction of alkanes. Click on image below for more

VIDEOS ON ALKANES

USES OF ALKANES VIDEO

Alkanes are used as fuel and solvents. Refer to page 140 Concise Chemistry by Anne Tindale or page 264 CSEC Chemistry by Naresh Birju

BIOGAS PRODUCTION

Biogas is a renewable energy source produced by naturally occuring anaerobic bacteria breaking down organic matter e.g manure, organic food waste etc. Biogas produced is 60% methane and 40% carbon dioxide.

• Physical properties are similar to that of the alkanes
• Non polar compounds
• Insoluble in water but soluble in non polar organic solvents
• Less dense than water
• Low melting points and boiling points that are slighly lower than that of their corresponding alkanes
• Alkenes are unsaturated because of the presence of the double bond.
• General formula Cn H2n

Alkenes

Chemical properties/reactions of alkenes

The two equations on the bottom right are (i) adding hydrogen halides and (ii) adding acidified KMnO4. The balanced equation for reaction (ii) on the bottom is not required; only the reagents , conditions and the products need to be known. CLICK HERE FOR MORE.

VIDEO on reactions of alkenes

This video looks at some of the reactions of alkenes

Comparison of Alkenes and Alkanes

They burn easily giving off a lot of energy when burnt and are easily transportable

Uses of alkanes and alkenes. Refer to page 264 CSEC Chemistry by Naresh Birju

VIDEO on Alkanes and Alkenes

Here is another Terry David video on the topic we just discussed Alkanes and Alkenes. The video also includes Strucutural Isomerism in the end

1. Structural isomerism

The video on the right looks at structural isomers in both alkanes and alkenes. Click here for more tips on structural isomers

Alcohols/Alkanols

General formula CnH2n+1 OHFunctional group=hydroxyl group - OH Alcohols are miscible in water because water is a polar solvent and and alcohols are also polar molecules. ("like dissolves like") Solubility decreases as the number of carbon atoms per molecule increases. Only methanol, ethanol and propanol are soluble in water.

Chemical properties of alcohols

Click here for more

Fermentation

This is the anaerobic production of alcohol from carbohydrates in the presence of yeast. Yeast produces enzymes which first break down the complex carbohydrates( like starch or sucrose) to simple sugars mainly glucose. The yeast also contains another enzyme zymase which converts glucose to ethanol and carbon dioxide. Click here.

VIDEO ON ALCOHOLS

This video is done by Terry David. It includes everything we saw on the previous slides on alcohol and esterification which we will look at when we look at carboxylic acids next

Organic (Alkanoic) acids: carboxylic acid

Aqueous solutions of alkanoic acids react in a similar way to inorganic acids like hydrochloric acid. The reactions are less vigorous as they are weak acids and are partially ionized in aqueous solution as seen in the equation below.

Chemical properties of carboxylic acids

Reactions with carbonates

Reactions with metals

Esterification: a special reaction of organic acids

In the esterification process, the -OH is lost from the carboxylic acid functional group(-COOH) and the -H is lost from the alcohol functinal group (-OH) to form water while the remaining parts of the two organic compounds join together Where they join is referred to as the ester linkage (-COO) When you are drawing how an ester is formed, it is recommended that you draw the acid first and the alcohol after and you ensure that the two functional groups are facing each other so you can easily show how water is removed However when you are naming the ester, you name it in reverse, the alcohol part first with a -yl at the end and the acid part last with -anoate at the end as seen below

VIDEO

Remember a more detailed description of the esterification process is seen in the "Terry David Alcohols video found on an earlier slide (page/slide26) starting at time 13 mins 30 secs . Click here to return to that page!

Hydrolysis of esters

In the hydrolysis reaction, the ester is broken up into its components on the addition of water and heat. This is achieved by either heating the ester with (i) dilute acid or (ii) dilute alkali View the video on the left and also click here for more

Saponification of fats and oils: making soaps

This process follows along the principle of ALKALINE HYDROLYSIS OF ESTERS where the salt of the acid is formed instead of the acid itself.During saponification, large ester molecules found in animal fats and vegetable oils undergo ALKALINE HYDROLYSIS by being boiled with NaOH or KOH and the potassium or sodium salt of the long chain organic acid that is formed in the process is what we call SOAP. The other product formed is the alcohol glycerol.

The video above shows the laboratory method of preparing soap. Pay attention to the additional materials needed (ethanol and saturated sodium chloride solution) and their roles

1.Fats and oils are special esters. They are often called tri-esters or tri-glycerides. They occur naturally and are the products of LONG CHAIN ORGANIC ACIDS also known as fatty acids and a special alcohol called glycerol (It has 3 -OH groups in its structure) Click here for more

2. When fats and oils undergo alkaline hydrolysis, they will form back the glycerol and instead of getting the fatty acid or long chain acid, you will get the SODIUM OR POTASSIIUM SALT OF THE FATTY ACID WHICH IS WHAT WE CALL SOAP.Click here for more.

3. Click on the video below

This is a short video on how soaps(and detergents) work

VIDEO

VIDEO

This video shows the differences and similarities between soapy detergents(soaps) and soapless detergents( often just called detergents) Please refer to CSEC Chemistry by Anne Tindale pages 145-146 Click here for more.

SUMMARY VIDEO

Here is another excellent Terry David video which summarizes all the reactions of carboxylic acids and includes esterification, hydrolysis of esters and saponification. Click here for another video.

Polymers

These are long chain organic molecules(macromolecules) made from several repeating units called monomers. There are two types of polymers: addition polymers and condensation polymers Click here for more

Addition polymerization

Click here to view more on addition polymers

Condensation polymers

POLYESTER monomers : diacids and dialcohols. Linkage : ESTER LINKAGE

POLYAMIDESynthetic polyamides monomers: diacids and diamines Natural polyamides monomers: amino acids Linkage: amide or peptide linkage

POLYSACCHARIDEmonomers: monosaccharides e.g glucose Linkage: ether or glycosidic linkage

Click on each condensation polymer for more information on each

VIDEOS ON CONDENSATION POLYMERS

Uses of addition and condensation polymers. Click here

Advantages of polymers (Concise Chemistry by Anne Tindale page 150)

Click here to see the negative impact of polymers(plastics on the environment)

VIDEO on Polymers

This is the final topic in Organic Chemistry. View this Terry David Video which deals in detail with Polymers and how they are formed

Thanks!

Here is another summary video by Kerwyn Springer which summarizes ester formation, ester hydrolysis, saponification and soaps and soapless detergents

Summary of the conditions necessary for fermentation

• carbohydrate material
• aqueous solution
• neutral pH
• Temperature of 37 degrees Celsius
• no air(anaerobic conditions)
• yeast (to supply enzymes

Fermentation stops when the ethanol concentration reaches 14% because the enzyme zymase is denatured. Fractional distillation is then used to separate the water from the ethanol to get a higher concentration of ethanol, about 96%