Topic: Esters – structure and properties

Target group

Student of an eight‑year elementary school

Core curriculum:

Elementary school. Chemistry.

IX. Hydrocarbon derivatives. Student:

6) explains the esterification reaction; writes the equations for the reaction between carboxylic acids (methane, ethane) and alcohols (methanol, ethanol); forms the chemical and common names of the esters on the basis of the names of respective carboxylic acids (methane, ethane) and alcohols (methanol, ethanol); plans and performs an experiment to obtain an ester with the given name; describes the properties of esters in terms of their use.

General aim of education

The student acquires knowledge and skills about the topics discussed in the classes

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• what are the esters, what are their properties and applications;

• describe the structure of esters;

• what is the reaction of esterification;

• write the reaction equation between carboxylic acids and monohydric alcohols;

• create names of esters derived from given names of acids and alcohols;

• design an experience to obtain an ester with the given name;

• explain the role of concentrated sulfuric acid as a catalyst in the esterification reaction.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• methodician or green, yellow and red cards.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. The teacher introduces students to the question of the occurrence of esters in nature, such as the scent of flowers, and their use in industry, e.g. the production of perfumes and essential oils (cosmetic, food). It encourages them to exchange insights on this subject.

2. The teacher announces a movie. He instructs his pupils to write a research question and a hypothesis in the form provided in the abstract. Then he plays the video and the students note their observations and conclusions. The teacher points the person who shares his insights and explains the reasonableness of the conclusions noted.

3. The teacher writes on the table the equation of esterification reactions on the total patterns using the substrates used in the experiment during the film. Then, the same equation stores on the structural formulas and explains the mechanism of the esterification reaction. Instructs students to look at the interactive illustration (abstract) that discusses this reaction. He also explains the role of sulfuric acid in the course of esterification. With reference to the formula created in the esterification reaction equation, the teacher displays the general formula of the esters from the abstract and explains it. Then it creates a systematic name of esters and a common name - it presents students with the principles of their creation. Displays a table with the names of acids and esters and ester formulas; can also instruct students to look at them directly in the abstract. He also encourages them to familiarize themselves with the slider presentation presenting names, general formulas and illustrations referring to the aromas of esters.

4. The teacher conducts - in the form of a show - an experiment. Before joining the action, he asks the students to formulate a research question and write it down in the work sheets. After the experiment, a summary of observations and conclusions is made, which should also be included in the work sheets. The teacher asks a willing student to write on the board the equation of reaction that took place during the experiment (if there are no volunteers, he writes the equation on the board himself), and then explains its mechanism.

5. The teacher displays on the interactive board a general record of the esterification reaction (from the abstract) and discusses it..

6. The lecturer writes on the board and explains the course of the equation of the hydrolysis reaction of an exemplary ester.

7. The teacher plays the recording of the abstract. Every now and then he stops it, asking the students to tell in their own words what they have just heard.This way, students practice listening comprehension.

8. Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or straightens the statements of the proteges.

Summary

1. The teacher asks the students to finish the following sentences:

   • Today I learned ...

   • I understood that …

   • It surprised me …

   • I found out ...

   The teacher can use the interactive whiteboard in the abstract or instruct students to work with it

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

2. Make at home a note from the lesson using the sketchnoting method.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Esters – structure and properties

Esters are compounds composed of carbon, hydrogen and oxygen atoms.

General formula for esters is ${\text{R}}_{\text{1}}{\text{COOR}}_{\text{2}}$

${\text{R}}_{\text{1}}$ – hydrocarbon group derived from carboxylic acid
${\text{R}}_{\text{2}}$ – hydrocarbon group derived from alcohol

Group $\text{– COO –}$ is called the ester group.

Examples of esters with a characteristic odour.

In previous lessons you learned about the structure and properties of two important groups of organic compounds: alcohols and carboxylic acids. Remember their structure.

The reaction of carboxylic acid and alcohol produces esters. This reaction is called an esterification reaction.

General equation for the esterification reaction:

${\text{R}}_{\text{1}}$ – hydrocarbon group derived from carboxylic acid
${\text{R}}_{\text{2}}$ – hydrocarbon group derived from alcohol

In order to examine the properties of esters, we will perform an experiment which will result in ethyl acetate.

The use of lower esters of carboxylic acids results from their properties.

• Esters are an important group of compounds in living organisms.

• Esters are obtained as a result of esterification reaction, i. e. reaction of carboxylic acids with alcohols.

• In the esterification reaction sulfuric acid acts as a catalyst, i. e. accelerates the reaction process.

• General formula for esters is ${\text{R}}_{\text{1}}\text{COO}{\text{R}}_{\text{2}}$, and the characteristic group is the ester group$\text{–}\text{COO –}$.

• Esters are slightly soluble in water, but dissolve well in organic solvents and are therefore used as solvents for paints and varnishes.

• Some esters have a pleasant smell and these are used, among others, in the production of perfumes and essential oils.