Introduction:
An ester is an organic compound that is created from a reaction between an acid and an alcohol, usually with the loss of water. Many esters contain veer distinct odors, which has led to them being used for artificial flavoring and fragrances.
Esters can be synthesized artificially in labs by combining alcohols and acids of different strengths. This lab contained the synthesis of an ester by allowing different carboxylic acids to react with alcohols, using sulphuric acid as a catalyst, to create esters and allow the student to identify them by their distinct smell.
The smell was distinguished by the different compounds that were created in the dehydration synthesis reaction. Different safety techniques were taken into consideration to ensure the lab was correctly executed. Special care was made while handling the sulfuric acid due to its corrosiveness, while the special ‘wafting’ technique was used to detect the odors of the newly created esters. To make sure the lab was done with the greatest amount of safety, all participants wore eye protection, tied up any loose clothing, tied long hair back, and maintained a safe, well-behaved manner.
Purpose:
The purpose of this lab was to observe the synthesis of esters and identify the odor of each and then to write chemical equations of each ester synthesized.
| Chemical Name | Physical Properties | Potential Health Effects |
| Butanoic Acid | colorless liquid with a pungent, putrid odor. | No physical harming properties to humans, just small rodents |
| Salicylic Acid | White, odorless crystals | Contact with skin or eyes could lead to irritation, ingestion may cause nausea, headaches, and dizziness |
| Malonic Acid | Fine white, odorless crystals | Causes both skin and eye irritation, Ingestion of sizable amounts can cause “salicylism”, as evidenced by abdominal pain, vomiting, increased respiration, and mental disturbances, irritation to skin and eyes if exposed |
| Ethanoic Acid | Colorless liquid, with strong vinegar like odor | Severe irritation, and burns to eyes and skin, breathing can irritate lungs |
| Propionic Acid | Clear oily liquid, slightly pungent irritating odor | Causes coughing and sneezing, ingestion leads to irritation and burns of the digestive tract, causes severe skin and eye irritation and burns |
| Sulfuric acid (SO4/ H2SO4) | – Clear oily liquid
– Odorless | – Poison
– Corrosive – Can cause severe burning to all body tissue – Inhalation produces damaging effects, including irritation of the nose and throat and labored breathing – Ingestion can cause severe burns of the mouth, throat, stomach, leading to death – Skin contact has symptoms of redness and pain – Any eye contact and blur vision and cause blindness |
| Methanol (CH3OH) | -Clear, colorless liquid
– Characteristic odor | – Poison
– Inhalation causes a slight irritation – Symptoms include headache, nausea, blindness, and death – Skin contact may cause the skin to become dry and cracked – Irritant upon eye contact |
| Propanol CH3(CH2)2OH | – Clear, colorless liquid
– Alcohol odor | – Symptoms include irritation of eyes, nose and throat and headache
– Ingestion can cause nausea, vomiting and drowsiness – Eye contact vapors are irritation to the eyes and may cause redness and tearing |
| 2-methyl-1-propanol (CH3)2CHCH2OH | – Clear, colorless solution
– Sweet-musty odor | – Inhalation symptoms include headaches, dizziness and muscles weakness
– Ingestion may cause nausea, vomiting and diarrhea – Skin contact causes irritation, redness and pain – Eye contact cause irritation and blurred vision |
| Ethanol | -Colorless liquid
– Agreeable odor | – Can irritate the skin
– Exposure can irritate the eyes, nose, mouth and throat – Breathing ethanol can irritate the lungs causing coughing and/or shortness of breath – Exposure can cause headache, nausea, a feeling of heat and drowsiness |
Procedure:
- Smell reactants before starting
- Label four test tubes A-D and place them in a test tube rack
- Into the appropriate test tube, using droppers, transfer an approximate amount of alcohol and carboxylic acid according to a given table
- Add four drops of concentrated sulphuric acid into each test tube
- put 150 mL of water into a test tube and place the test tubes into the water, and heat the water on a hot plate to about 60 C, leave the test tubes in the hot bath for 15 minutes cool the test tubes by immersing in a cool water bath (second beaker)
- carefully note the odor
- using a dropper add 5 mL of distilled water to each test tube
- waft the test tubes again
- dispose of all materials following the reagent disposal instructions
Observation Table:
Table 1
| Reactants | Odor |
| Butanoic Acid | |
| Methanol | |
| Ethanoic Acid | |
| 1-Propanol | |
| Salicylic Acid | |
| Propanoic Acid | |
| 2-Methyl-1-Propanol | |
| Maonic Acid | |
| Ethanol |
Table 2
| Products | Odor (After cooled) |
| Test Tube A | |
| Test Tube B | |
| Test Tube C | |
| Test Tube D |
Table 3
| Products | Odor (After adding distilled water) | Appearance (after adding distlled water) |
| Test Tube A | ||
| Test Tube B | ||
| Test Tube C | ||
| Test Tube D |
What is the independent variable, dependent variable, controlled variables?
where is the methods, results, discussion, and conclusion?