CHE143 - Lab Report : Organic Synthesis - Formation of An Ester (2015) PDF

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TABLE OF CONTENT Title Page 1 Abstract……………………………………… 2 2 Objectives……………………………………. 3 3 Material & Apparatus……………………….. 4 4 Procedures…………………………………… 5 5 Data & Results………………………………. 6 6 Discussions………………………………….. 7–9 7 Conclusion…………………………………... 10 8 Reference…………………………………….. 11 9 Appendix………...

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TABLE OF CONTENT

1 2 3 4 5 6 7 8 9

Title Abstract……………………………………… Objectives……………………………………. Material & Apparatus……………………….. Procedures…………………………………… Data & Results………………………………. Discussions………………………………….. Conclusion…………………………………... Reference…………………………………….. Appendix…………………………………….

Organic Synthesis : Formation Of An Ester Lab Report

Page 2 3 4 5 6 7–9 10 11 12

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1.0 ABSTRACT In chemical engineering or in chemical subject, there is a chemical compound named esters. Esters are derived from an acid (organic or inorganic) in which at least one –OH (hydroxyl) group is replaced by an alkyl group. Usually, esters are derived from a carboxylic acid and alcohol. Esters with low molecular weight are commonly used as fragrances and found in essential oils too. Esters used in fragrances because it can produce a really good smell. Ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Esters named came from the simplest carboxylic acids are commonly used. Esters are more polar than ethers but less polar than alcohols. They participate in hydrogen bonds as hydrogen-bond acceptors, but cannot act as hydrogen-bond donors, unlike their parent alcohol. Consequently esters are more volatile than carboxylic acids ot similar molecular weight. Esters are widespread in nature and are widely used in industry. Esters are responsible for the aroma of many fruits, including apples, pears, bananas, pineapples and strawberry. The reaction to complete esters are alcohol and carboxylic acid. It is common in organic chemistry and biological materials, and often have the characteristic pleasant, fruity odor. It also used in flavouring and as polymers. The example of esters name are, Allyl hexanoate, benzyl acetate, butyl acetate and the odor or occurrence are pineapple,(pear,strawberry,jasmine) and (apple,honey) respectively.

Organic Synthesis : Formation Of An Ester Lab Report

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2.0 OBJECTIVES 1) To synthesise the ester compound. 2) To differentiate between alcohol, carboxylic acid, and ester compounds by identifying the functional groups for each. 3) To understand the process of esterification. 4) To learn how to name the ester compounds. 5) To find out the applications of the ester.

Organic Synthesis : Formation Of An Ester Lab Report

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3.0 MATERIAL AND APPARATUS Apparatus :1) 250 mL beaker 2) 400 mL beaker 3) Test tube 4) Spatula 5) Dropper 6) Hot Plate 7) Stopwatch Material :1) Distilled Water. 2) Acetic Acid ( Ethanoic Acid ) 3) Propanoic Acid ( Propionic Acid ) 4) Methanol 5) Ethanol

Organic Synthesis : Formation Of An Ester Lab Report

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4.0 PROCEDURES 1) 400 mL beaker are filled about half full with water to prepare the hot water bath. Heat the water to boiling and then turn off the hot plate. 2) The ester are prepared. The table data at the backside are used as guide. For each ester, 10 drops of the organic acid are placed in a dry test tube. Then 10 drops of the appropriate alcohol and 2 drops of concentrated sulphuric acid are added in the test tube respectively. The test tube was placed into the beaker of hot water and let stand for five minutes. 3) The odour of the ester is more easily detected when the ester is mixed in some water. Never try to directly smell the ester while it is still hot. About 100 mL of water was added in a 250 mL beaker. The contents of the test tube was poured into the beaker and swirl it to mix the contents by using the spatula. The odour of the ester was carefully smell after it is mixed with water by waving some of the vapors toward your nose. This action is refer as wafting. The odour was identified. Observations were recorded on the table. 4) Steps 2 and 3 are repeated to prepare the 4 esters in total. 5) All waste solutions was poured down to the organic waste tank.

Organic Synthesis : Formation Of An Ester Lab Report

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5.0 DATA AND RESULTS Trial

Acid

Alcohol

Ester name and

Odour

Structure name 1

Acetic Acid

Ethanol

Ethyl Ethanoate

(Ethanoic Acid)

CH3CH2OH

CH3COOCH2CH3

CH3COOH 2

Vinegar-like odour, Not too strong.

Acetic Acid

Methanol

Methyl Ethanoate

(Ethanoic Acid)

CH3OH

CH3COOCH3

Propanoic Acid

Ethanol

Ethyl Propanoate

(Propionic Acid)

CH3CH2OH

CH3CH2COOCH2CH3

Odourless

CH3COOH 3

CH3CH2COOH 4

The most pungent, very sharp smell

Propanoic Acid

Methanol

Mthyl Propanoate

Mild smell,

(Propionic Acid)

CH3OH

CH3CH2COOCH3

Smell like fruit

CH3CH2COOH Table 1

Organic Synthesis : Formation Of An Ester Lab Report

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6.0 DISCUSSIONS Lewis Structure of Propanoic Acid:

H

H

H

O

C

C

C

H

H

Formula of Propanoic Acid:

CH3CH2COOH OH

Reaction of Propanoic Acid and Methanol H

H

O

H

H

H O

H

H – C – C – C – O – H + H – C – O – H → H – C – C – C – O – C – H + H2O H

H

Propanoic Acid

H

Methanol

Organic Synthesis : Formation Of An Ester Lab Report

H

H

H

Methyl Propanoate

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A Carboxylic acid (-COOH group) can react with an Alcohol (-OH group) to form a new product, Ester (-COOR). From above Lewis structure diagram, a Propanoic Acid is reacted with a Methanol, a type of alcohol to produce a Methyl Propanoate and water. Propanoic acid is a carboxylic acid with a chemical formula C3H5COOH and functional group –COOH while Methanol is an alcohol with a chemical formula CH3OH and functional group –OH. When this reaction is occur, Propanoic acid will lose it OH- and Methanol will lose H+ ion. An ester, Methyl Propanoate, CH3CH2COOCH3 will become a product and water will form as a side product. The water, H2O is formed from the OH- ion from the Propanoic Acid and the H+ ion from the Methanol. This reaction can be used to synthesis an Ester. Methyl Propanoate is an ester with a sweet and fruity odor. It also usually use as a solvent for cellulose nitrate and as a raw material for production of varnishes, paint and other chemicals. Besides that, it is also used as a flavouring and fragrances. An ester has a different solubility in water for each kind, but a small esters are fairly soluble in water. Due to the increase length in chain, the solubility is decreasing. For an example, a Methyl Methanoate, HCOOCH3, is more soluble in water than Ethyl Ethanoate, CH3COOHCH2CH3. The reason for this is that although an esters cannot form a hydrogen bond with each other, they can form a hydrogen bond with the water molecules. One of a partially-positive hydrogen atoms in water molecules can be attracted to one of the lone pairs of oxygen in the esters thus, a hydrogen bond is formed. This intermolecular attraction will release enough energy sufficiently to solvate the ester. As for the ester with longer chain, the hydrocarbon portion forces itself between the water molecules and break the hydrogen bonds between the water molecules. This makes the solubility decreases. Based on the report from the experiment, the solubility of the ester can be rank based on their number of hydrocarbon and their length. It was shown in the table 2 below.

Organic Synthesis : Formation Of An Ester Lab Report

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Ester and The Structured Formula

Solubility in water

Methyl Ethanoate Higher

CH3COOCH3 Ethyl Ethanoate CH3COOCH2CH3 Methyl Propanoate CH3CH2COOCH3 Ethyl Propanoate CH3CH2COOCH2CH3

Lower Table 2

Organic Synthesis : Formation Of An Ester Lab Report

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7.0 CONCLUSION Esters also produce some other smell like souring smell like alcohol and acid because esters are produce from alcohol and acid. Example of the alcohol were methanol and ethanol. It produced two different power of smell. The smell is like the same, but the power of the smell make them different. Methanol and ethanol are reacted with acid to produce esters. Esters can be smell easily when we mix it with water and never to try smell directly the esters while it still hot. Waving some vapors to your nose to smell it correctly. We must use esters correctly because it can make air pollution to our environment and also our nature. The wasted esters, alcohol or acid must be thrown it in the right way. We cannot dump it into the pond, river or sea. It can affect the habitat in the water. The fishes may die easily because of our bad manners. For this experiment, the solution produce two types of smell and one is odorless.

Organic Synthesis : Formation Of An Ester Lab Report

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8.0 REFERENCE 1) 2006, ORGANIC CHEMISTRY, McGraw Hill Inter. Edittion. 2) Web , ChemWIKI a. http://chemwiki.ucdavis.edu/Organic_Chemistry/Esters/Properties_of_Esters 3) Web, Wikipedia a. http://en.wikipedia.org/wiki/Ester

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