Some Important Oxygen-Containing Organic Compounds

6 CHEMISTRY GRADE 11  O R C O H + C R' H+ O R H O O R' + H O H SOME IMPORTANT OXYGEN-CONTAINING ORGANIC COMPOUNDS Unit Outcomes At the end of this unit, you will be able to: ) classify organic compounds ) write the structural formula and IUPAC names of alcohols, ethers, aldehydes, ketones, carboxylic acids and esters ) give the general formulas of alcohols, ethers, aldehydes, ketones, carboxylic acids and esters ) describe some physical and chemical properties of alcohols, ethers, aldehydes, ketones, carboxylic acids and esters ) develop skills in naming and writing the molecular and structural formulas of alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, anhydrides, amides, and acid chlorides ) predict and correctly name the products of organic reactions, including substitution, addition, elimination, esterification, hydrolysis and oxidation reactions ) perform activities to prepare an alcohol (Katikalla), and a carboxylic acid ) test for the carboxylic acid and ester functional groups ) write the general formula of fats and oil and the structures for some common triglycerides ) give the structures, properties and uses of fats and oils, and demonstrate scientific enquiry skills, including: observing, classifying, comparing and contrasting, asking questions, drawing conclusions, applying concepts and problem solving. Introduction Start-up Activity Perform the following activity in groups and present your response to the rest of the class. Take turns to name an item that contains organic molecules that we use in daily life, and identify what class of organic compound (s) it contains. 6.1  At the end of this section, you will be able to: ) classify organic compounds. Classification of organic compounds Why is classification of organic compounds needed? What is the basis of the classification? In Grade 10, you have learned about some general organic reactions of hydrocarbons. In this unit, you will continue to learn about more functional groups: oxygencontaining functional groups. The oxygenated hydrocarbons include alcohols, ethers, aldehydes, ketones, carboxylic acids and esters. Alcohols occur widely in nature and have many industrial and pharmaceutical applications. Methanol, for example, is one of the most important of all industrial chemicals. Ethers are relatively resistant to chemical transformation and are often used as solvents in chemical reactions. Can you name the common functional groups and give an example for each functional group? Aldehydes and ketones contain a carbonyl group that consists of a carbon–oxygen double bond (C=O). Many compounds found in nature have aldehyde or ketone functional groups. Aldehydes have pungent odors, whereas ketones tend to smell sweet. Carboxylic acids and esters are present in many fruits and flowers. Many carboxylic acids are used as food additives in jams, jellies, candies and pickles, etc. In this unit, you will also learn about fats and oils which are esters. CHEMISTRY GRADE 11 6.2  At the end of this section, you will be able to: ) define alcohols ) tell the functional group of alcohols ) classify alcohols based on the number of hydroxyl groups ) write the general formulas of monohydric alcohols ) write the molecular formulas and the names of the first six members of the monohydric alcohols ) give the IUPAC names for the given alcohols ) classify monohydric alcohols based on the number of alkyl groups attached to the carbon atom carrying the hydroxyl group ) give some examples for primary, secondary and tertiary alcohols ) describe the physical properties of alcohols ) explain general methods of preparation of alcohols ) explain the industrial preparation of ethanol ) perform an experiment to prepare ethanol from sugar ) explain the chemical reactions of alcohols such as oxidation, reaction with active metals, esterification and dehydration ) carry out an activity to show chemical reactions of alcohols with active metals ) write the molecular formulas and names of the first six members of ethers ) give the IUPAC names for given ethers ) describe the physical properties of ethers ) explain the general methods of preparation of ethers ) explain the use of ethers, such as solvent inorganic reactions. Alcohols and Ethers Activity 6.1 Discuss the following questions in groups, and write a report. Present your report to the class. 1. List some alcohols you know. Name the alcohol used in alcoholic beverages. What are the uses of alcohols in industry? 2. Ethiopia uses an alcohol blended with gasoline to drive cars. What is the name of the alcohol? 3. Hand sanitizers are used as an alternative to washing hands to kill most bacteria and viruses that spread colds and flu. Which alcohol (s) is present in hand sanitizers? 4. Explain the effects of using carbon-based fuels on the increase in carbon dioxide in the atmosphere and its consequences. What do you think when you hear the word “alcohol”? Can you define alcohol? Give a few examples of the uses of alcohols. Most people think of two common alcohols: the substance that intoxicates people, and the one used in clinics and hospitals. However, there are many types of alcohol. The only alcohol present in all alcoholic beverages is called ethanol. Other alcohols are used for different purposes. Alcohols are derivatives of hydrocarbons in which one or more of the hydrogen atoms in the hydrocarbon have been replaced by a hydroxyl group (–OH). The functional group in an alcohol is an –OH (hydroxyl) group, which is responsible for imparting certain chemical and/or physical properties to the compound. In alcohols, the hydroxyl group is directly attached to carbon atom(s) of an aliphatic system. Example 6.1 H H C H Methanol OH H H H C C H H Ethanol OH H H H H C C C H H H OH 1-Propanol (Propan-1-ol)