carboxylic acids grp 5

Carboxylic Acids and Their Derivatives

Lab Performed by 1Nur9-Grp 5Elias, Jose Emmanuel D.

Esperanza, John Ruben A.Flores, Norman KarlGenilla, Jonathan L.Manalo, Michelle C.

Carboxylic Acids• INTRODUCTION• Carboxylic acids are weak acids. They have sour or tart taste, produce

hydronium ions in water, and neutralizes base. Carboxylic acid reacts with an alcohol to form an ester. In an ester, the –H of the carboxylic acid is replaced by an alkyl group. Aspirin is an ester as well as carboxylic acid. Amines and amides are organic compounds that contain nitrogen. Many nitrogen containing compounds are important to life as components of amino acids, proteins and nucleic acid: DNA and RNA. Many amines that exhibit strong physiological activity are used in medicine as decongestants, anesthetics, and sedatives. Amides are derived from carboxylic acids and amines. In biochemistry, the amide bond is called the peptide bond, which links amino acids in proteins.

CARBOXYLIC ACIDS• CARBOXYLIC ACID• In carboxylic acids, the functional group is the carboxyl group,

which is combination of the carbonyl group and hydroxyl group.• The carboxyl functional group maybe attached to an alkyl group or

an aromatic group.• O• ‖ • C —OH –COOH CO2H • • You encounter carboxylic acids when you use a vinegar salad

dressing, which is a solution of acetic acid and water, or experience the sour taste of citric acid in grapefruit or lemon.

Solubility, Effervescence, and Precipitate Formation of Carboxylic

Acids and Amines

Contents

• Results• Explanations

– Intermolecular bonding– Chemical equations

ResultsSample Solubility in H2O + Na2CO3 →

Effervescence+ HCl → Formation of precipitate

Acetic acid Soluble 2 – 3 drops No precipitate in yellow solution

Triethylamine Soluble 5 drops Bubbly brown top layer (precipitate) with liquid bottom layer

Benzoic acid Insoluble 5 drops, still no effervescence

White precipitate on top of colorless liquid

Explanations

Intermolecular bonding

Acetic acid

CH3 – C – OH + IIO. .

. .

. .H

OH

.. ..

Acetic acid is soluble in water due to its one – carbon length and three hydrogen bonding possibilities.•Carbonyl oxygen with hydrogen of water•Hydroxyl oxygen with hydrogen of water•Hydroxyl hydrogen with oxygen of water

Triethylamine

CH3 – N – CH3ICH3

. .H

OH

.. ..

Triethylamine is slightly soluble in water due to the nitrogen in the amine forming an H – bond with a hydrogen of water. Primary and secondary amines have nitrogen (amine) to hydrogen (water) bonding and hydrogen (amine) to oxygen (water) bonding. But in triethylamine, a tertiary amine, only the nitrogen (amine) to hydrogen (water) bonding is possible.

Benzoic acid

HO

H

.. ..

C – OH +IIO..

..

..

Benzoic acid is insoluble in water for two reasons.

•The carboxyl group is bonded to the benzene ring. Benzene is insoluble in water.•There are seven carbons in the benzoic acid molecule. Carboxylic acids with five or more carbons are insoluble in water.

Chemical equationsAcetic acid

CH3COOH + H2O + Na2CO3 → CH3COONa + H2O + CO2↑

CH3COONa + H2O + HCl → CH3COOH + NaCl + H2O

Bubbles of carbon dioxide were formed when sodium bicarbonate was added to the acetic acid solution. And, a carboxylic acid salt (sodium acetate) was formed (and dissolved in water).

No precipitate was formed after the addition of hydrochloric acid to the sodium acetate solution. Since the products (acetic acid and sodium chloride) were both dissolved in water, no precipitate was formed.

Triethylamine

1. (CH3CH2)3N + H2O + Na2CO3 →(CH3CH2)3N + Na2CO3 + H2O + CO2↑

2. (CH3CH2)3N + Na2CO3 + H2O + HCl → (CH3CH2)3N + H2O + NaCl + CO2↑

The triethylamine remained untouched after the addition of sodium bicarbonate. Instead, the sodium bicarbonate decomposed into sodium carbonate, water, and carbon dioxide (effervescence) (eq. 1). Then, the hydrochloric acid was added, yielding sodium chloride and carbonic acid. Carbonic acid eventually broke down into water and carbon dioxide, thus producing a second batch of effervescence. Once again, the triethylamine was untouched after the addition of hydrochloric acid (eq. 2).

• No bubbles were formed in the benzoic acid solution after the addition of sodium bicarbonate. In fact, benzoic acid is insoluble in water at room temperature, but soluble in water at boiling point (eq. 1). The benzoic acid crystals were seen floating on water surface, even after the addition of hydrochloric acid. Instead, the sodium bicarbonate reacted with hydrochloric acid, producing sodium chloride and carbonic acid, which later broke down into carbon dioxide and more water (eq. 2).

1. C6H5COOH + H20 + NaHCO3 → no reaction2. C6H5COOH + H20 + NaHCO3 + HCL → C6H5COOH + NaCl + H2O

Benzoic acid

C6H5COOH + H2O + Na2CO3 → no reaction

C6H5COOH + H2O + Na2CO3 + HCl → C6H5COOH + H2O + NaCl + CO2↑

There was no bubble formation after adding sodium bicarbonate since benzoic acid is insoluble in water at room temperature (but soluble at water’s boiling point).

The white “precipitate” in this chemical reaction (after the addition of sodium bicarbonate and hydrochloric acid) was the insoluble benzoic acid. The only reaction that occurred here was between the added compounds (sodium bicarbonate and hydrochloric acid), which formed sodium chloride, more water, and carbon dioxide effervescence.

Study Question 1 for Solubility

• Account for the difference in solubility: the carboxylic acids and amines in 1) water and 2) sodium bicarbonate and 3) hydrochloric acid.

• Intermolecular bonding and solubility in water

• Acetic acid is soluble in water because of the following reasons, besides from its polarity (the carboxyl group provides the acid’s polarity).


• It has only two carbons. Aldehydes and ketones with at most four carbons are infinitely soluble in water.

• There are three hydrogen bonding possibilities in acetic acid.– Carbonyl oxygen H – bonds with hydrogen of water.– Hydroxyl oxygen H – bonds with hydrogen of water.– Hydroxyl hydrogen H – bonds with oxygen of water.


• Trimethylamine is partly soluble in water due to the nitrogen in the amine molecule forms an H – bond with hydrogen of a water molecule. Primary and secondary amines have nitrogen (amine) to hydrogen (water) bonding, as well as hydrogen directly bonded to nitrogen (amine) to oxygen (water) bonding. But in triethylamine, a tertiary amine, only the nitrogen (amine) to hydrogen (water) bonding is possible, because no hydrogen is directly bonded to the nitrogen.


• Benzoic acid is insoluble in water at room temperature (but soluble in hot water) for two reasons.

• The carboxyl group is bonded to a benzene ring. Benzene is nonpolar and insoluble in water.

• There are seven carbons in the benzoic acid, six in the benzene ring plus one carboxyl carbon.


• Chemical reactions and equations• CH3COOH + H2O + Na2CO3 → CH3COONa + H2O + CO2↑

• CH3COONa + H2O + HCl → CH3COOH + NaCl + H2O

• Addition of sodium bicarbonate (Na2CO3) to the acetic acid solution produced effervescence, carbon dioxide bubbles. Also, a carboxylic acid salt was produced, sodium acetate (eq. 1). Later, hydrochloric acid was added to the sodium acetate solution. This reaction yielded acetic acid and sodium chloride; both products are soluble in water. Thus, no precipitate was formed after adding hydrochloric acid (eq. 2).


• (CH3CH2)3N + H2O + NaHCO3 → (CH3CH2)3N + Na2CO3 + H2O + CO2↑

• (CH3CH2)3N + Na2CO3 + H2O + HCl → (CH3CH2)3N + H2O + NaCl + CO2↑

• The triethylamine remained untouched after the addition of sodium bicarbonate. Instead, the sodium bicarbonate decomposed into sodium carbonate, water, and carbon dioxide (effervescence) (eq. 1). Then, the hydrochloric acid was added, yielding sodium chloride and carbonic acid. Carbonic acid eventually broke down into water and carbon dioxide, thus producing a second batch of effervescence. Once again, the triethylamine was untouched after the addition of hydrochloric acid (eq. 2).


• C6H5COOH + H2O + NaHCO3 → no reaction

• C6H5COOH + H2O + NaHCO3 + HCl → C6H5COOH + NaCl + H2O• No bubbles were formed in the benzoic acid solution after

the addition of sodium bicarbonate. In fact, benzoic acid is insoluble in water at room temperature, but soluble in water in hot water (eq. 1). The benzoic acid crystals were seen floating on water surface, even after the addition of hydrochloric acid. Instead, the sodium bicarbonate reacted with hydrochloric acid, producing sodium chloride and carbonic acid, which later broke down into carbon dioxide and more water (eq. 2).

AMINES, AMIDES AND SAPONIFICATION

AMINES

• Amines are considered as derivatives of ammonia (NH3) in which one or more hydrogen atoms is replaced with alkyl or aromatic groups. For example, in methylamine, a methyl group replaces one hydrogen atoms in ammonia. The bonding of two methyl groups gives dimethylamine, and the three methyl groups in trimethylamine replace all the hydrogen atoms in ammonia.

CLASSIFICATION OF AMINES

• Amines are classified the same way as alcohols by counting the number of carbon atoms directly bonded to a nitrogen atom. In a primary amine, one carbon is bonded to a nitrogen atom. In a secondary amine, two carbons are bonded to the nitrogen atom, and a tertiary amine has three carbon atoms bonded to the nitrogen.

AMINES

Name Structure

Primary Amine Ethylamine

Secondary Amine Dietheylamine

Tertiary Amine Triethylamine

Quaternary

Ammonium salt

Tetraethylammonium

bromide

PROPERTIES OF AMINES

• Amines have higher boiling points than alkanes of similar mass, but lower than the alcohols.

• Because amines contain a polar N—H bond, they form hydrogen bonds. However, nitrogen is not as electronegative as oxygen, which makes the hydrogen bonds in amines weaker. The —NH2 in primary amines can form more hydrogen bonds, which gives them higher boiling points than the secondary amines of the same mass. It is not possible for tertiary amines to hydrogen bond with each other(no N—H bonds), which makes their boiling points much lower and similar to those of alkanes.


• Amines are stonger proton acceptors than oxygen-containing organic compounds such as alcohols and ethers; that is, they are stronger bases than these compounds. A 0.1 M aqueous solution of methylamine has a pH of 11.8 and a 0.1 M of aqueous solution of aniline has a pH of 8.6. these solutions are sufficiently basic to turn red litmus paper blue. Carboxylic acid salts are the only other type of organic compound sufficiently basic to turn red litmus paper red.

AMIDES

• Amides are derivatives of carboxylic acid in which an amino group replaces the hydroxyl group

AMIDATION

• An amide is produced in a reaction called amidation, in which a carboxylic acid reacts with ammonia or a primary or secondary amine. A molecule of water is eliminated, and the fragments of the carboxylic acid and amine molecules join to form the amide, much like the formation of ester. Because a hydrogen atom must be lost from the amines, only primary and secondary amines undergo amidation.

ACETAMIDE

• -unlike other water-insoluble organic substances, saponification of an amide releases ammonia which is very distinct for its pungent and urine like smell.

• *red litmus paper turned blue on ACETAMIDE due to the presence of ammonia(weak base)

• -nitrogen atom in the molecule has a lone pair making it a proton acceptor

BASICITY OF AMINES

• Because amines acts as weak bases by accepting protons from water and producing hydroxide ions, their aqueous solutions are basic.


• Most of the K value for amines are less than 10^-3, which means that the equilibrium favored the undissociated amine molecules. Aqueous solutions of amines have basic pH values and turn litmus paper blue.

HYDROLYSIS OF AMIDES

• The most important reaction of amides is hydrolysis. In amide hydrolysis, the bond between the carbonyl carbon atom and the nitrogen is broken, and free acid and free amine are produced. Amide hydrolysis is catalyzed by acids, bases, or certain enzymes; sustained heating is also often required.


• Acidic or basic hydrolysis conditions have an effect on the products. Acidic conditions convert the product amine to amine salt. Basic conditions convert the product carboxylic acid to a carbxylic acid salt.

• (PICTURE COURTESY OF BOOK page 715)


• Amide hydrolisis under basic conditions is also called amide saponification, just as ester hydrolysis under basic conditions is called ester saponification.

• (PICTURE COURTESY OF BOOK PAGGE 715)


• Amide bonds are formed by the elimination of water. The reverse reaction called hydrolysis occurs when water is added back to the amide bond to split the molecule. When an acid is used, the hydrolysis products of an amide are the carboxylic acid and the ammonium salt. In base hydrolysis, the amide produces the salt of carboxylic acid and ammonia or amine.


• Of the various acid derivatives, amides are the least reactive toward nucleophilic attack, because the unshared electron pair on the nitrogen is delocalized to the carbonyl carbon through resonance.

• Thus, unlike most acyl halides or anhydrides, amides must be heated to boiling with aqueous acid or base in order to hydrolyze them. For a primary amide, the product will be ammonium ion and the acid (for acidic hydrolysis) or ammonia and carboxylate ion (for alkaline hydrolysis). The reaction mechanisms are similar to those for the hydrolysis of other acid derivatives.

SAPONIFICATION

• Procedure:• 1. Prepare 2 clean and dry text tubes. Place

1.0 triethylamine in tube 1, and pinch-amount of acetamide in tube 2. add 1.0 of dilute 6N NaOH solution to each tube and mix thoroughly.

• 2. Heat all 2 tubes in a boiling water bath for two minutes.

LAB EXPERIMENT: RESULTS

SAMPLE REACTION WITH LITMUS PAPER

TRIETHYLAMINE THE RED LITMUS PAPER TURNED BLUE

ACETAMIDE THE RED LITMUS PAPER TURNED BLUE

ESTERS

ESTERS

• An ester is similar to a carboxylic acid, except that the oxygen of the carboxyl group is attached to a carbon and not to hydrogen. In ester, the –H of the carboxylic acid is replaced by an O-akyl (alkoxy) group. Fats known as Triglycerides are esters of glycerol and fatty acids, which are long-chain carboxylic acids. Esters produce the pleasant aromas and flavors of many fruits such as bananas, strawberries, and oranges.

Introduction

• An ester is a carboxylic acid derivative in which the –OH portion of the carbonyl group has been replaced with an –OR group.

• The ester functional group is O

C O R

Study Question 2: Saponification

• The principle used in the saponification is hydrolysis. In amide hydrolysis, the bond between the carbonyl atom and the nitrogen is broken, and free acid and free amide are produced. Amide hydrolysis is catalyzed by acids, bases, or certain enzymes; also sustained heating is often required.


• Amide hydrolysis:• Hydrolysis under Acidic Conditions

• Hydrolysis under Alkaline Conditions

• Acidic or basic hydrolysis conditions have an effect on the products. Acidic conditions convert the product amine to amine salt. Basic conditions convert the product carboxylic acid to carboxylic acid salt.


• Acidic or basic hydrolysis conditions have an effect on the products. Acidic conditions convert the product amine to amine salt. Basic conditions convert the product carboxylic acid to carboxylic acid salt.

• Saponification helps differentiate the amides from the rest of other water-insoluble compounds because the test reacts on carbonyl atom and nitrogen when carbon is present in amides.

• Amides are capable of participating to H-bonding with water and other priotic solvents; the atom can accept hydrogen bonds from water and the N-H hydrogen atoms can donate H-bonds. As a result of interactions such as these, the water solubility of amides is greater than that of other hydrocarbons.

ESTERS

• General formula:

PROPERTIES OF ESTERS

– Boiling point: lower than alcohols and carboxylic acid.

– Cannot form hydrogen bonds because they do not have a hydrogen atom bonded to an oxygen atom.

– Solubility: rapidly decrease with increasing carbon chain length

– Most have pleasant odors such as raspberry, banana, pear, apple and pineapple.

Preparation of Esters

• General formula:

Esters can be prepared through a process called “Esterification”.

ESTERIFICATION

ESTERIFICATION• In a reaction called esterification, a

carboxylic acid reacts with an alcohol when heated in the presence of an acid catalyst. In the reaction, water is produced from the –OH removed from the carboxylic acid and an –H lost by the alcohol.

Lab Experiment-Esterification

• Procedure:• 1. Prepare two clean and dry test tubes. To tube

1, place pinch-amount of salicylic acid and 2.0 ml of methanol. To tube 2, place 2.0 ml of

95% ethanol and 1.0 ml of glacial acetic acid. Add slowly to both tubes five drops of conc. Sulfuric acid. (CAUTION: concentrated sulfuric acid is very corrosive. See first aid measures in case of accident.) Mix the contents of both tubes thoroughly.

Lab Experiment- Esterification

• 2. Heat both tubes in a boiling water bath until the either the odor of the alcohol or the acid used is no longer obvious. Prepare two evaporating dishes. In each dish, place 5.0 ml hot water. Pour the contents of test tubes 1 and 2 separately in the evaporating dish. Immediately note the odor of each sample and record your observations.

RESULTSSAMPLES ODORS

1-methanol and salicylic acid smell similar to efficascent oil

2-ethanol and acetic acid smell similar to a plastic balloon

Ethanol and Acetic Acid

Methanol and Salicylic Acid (Benzoic Acid)

• Both samples yield esters into which the –H of the carboxylic acids (Acetic Acid and Salicylic Acid) was replaced by an alkyl group.

• In the experiment the –OH group is lost from the carboxylic acid, a –H atom is lost from the alcohol and water is formed as a by-product. The results of this reaction was the substitution of an –OR group of the alcohol and for the –OH group of the acid.

Study Question 3

• Aside from amides and carboxylate esters, what are the other kinds of esters? Give their equations.• Methyl Ethanoate

• Ethyl Ethanoate

• Methyl Methanoate

• Ethyl Methanoate

Study Question 3• Methyl Ethanoate

• Ethyl Ethanoate

• Methyl Methanoate

• Ethyl Methanoate

These are four of the most common kinds of esters.

Study Question 4

• In the formation of esters, why is there a need to add a small amount of concentrated sulfuric acid?

• Formation of esters may be achieved through “esterification”. It is a reaction of a carboxylic acid and with an alcohol (or phenol) to produce an ester. In order for esterification to be achieved a strong catalyst is needed. The Sulfuric Acid (H2SO4) serves as a catalyst in the process of esterification which helps increase the chemical reaction.

Hydrolysis of Esters

Group 5

Structure of ASA

Figure1: Structure of Acetylsalicylic Acid

UsesAspirin is one of the most widely used drugs in modern society. It is most frequently used to treat mild to moderate pain or to reduce fever. Because of its anti-inflammatory action, aspirin is prescribed to individuals who suffer from joint inflammation conditions such as rheumatoid arthritis and osteoarthritis.

Hydrolysis of ASA

Figure2: Hydrolysis of Acetylsalicylic Acid

Introduction

Acetylsalicylic Acid(C6H4OCOCH3COOH) is the ubiquitous pain reliever known as aspirin. Chemically, aspirin is both an aromatic acid and an ester; analgesic properties not with standing, the compound is an excellent showcase for at least two or three principles of organic chemistry.

Salicylic Acid

(C6H4OHCOOH; aspirin's parent compound) and sodium salicylate

(C6H4OHCOONa) are useful for detecting iron compounds; they form colored

complexes with the Fe3+ ion. They can also be used in several organic chemistry

experiments which illustrate important principles.

Ester Saponification

Acid Hydrolysis

Acid Hydrolysis

“Acid Hydrolysis is the breaking of the carbon-oxygen single bond between the “alcohol” part and the “acid” part. It is also the most important reaction of esters.”

Acid Hydrolysis

“A carboxylic acid and alcohol are formed when an ester reacts with water.”

Hydrolysis

“The alkaline hydrolysis of ester involves reaction with hydroxide ions. The reaction can either use water or acid to hydrolyze ester.

Hydrolysis of Ester-General Reaction

O O ll H

+ ll

R-C-O-R’ + H-OH ------> R-C-OH + R’-O-H

Acid Hydrolysis of Methyl Acetate

O O ll H

+ ll

CH3-C-O-CH3 + H-OH -------> CH3-C-OH + CH3-OH


Base Hydrolysis

Base Hydrolysis

“Saponification reaction under basic conditions, hydrolysis of an organic compound in which the product is a carboxylic acid salt. All of the following go through saponification: esters, amides, fats and oils.”


“A reaction between the ester and a base to produce a carboxylic acid salt and alcohol. In this reaction, all carboxylic acid products are converted to its salt form due to the conditions of the basic reaction.”

Lab Report-Hydrolysis of Esters

• Acetate Ion (CH3COO-)• Basic Ferric Acetate Test: Dissolve a small

quantity of CH3COONa in 3 drops of distilled water. Add 3 drops of 0.5 M FeCl3 solution. If no color change is observed, add one drop of 6 M nitric acid. Record all observations on the data sheet.


• Figure 1. Structure of acetylsalicylic acid.• Aspirin is one of the most widely used drugs in modern society. It is most

frequently used to treat mild to moderate pain or to reduce fever. Because of its anti-inflammatory action, aspirin is prescribed to individuals who suffer from joint inflammation conditions such as rheumatoid arthritis and osteoarthritis.

• Figure 2. Hydrolysis of acetylsalicylic acid to acetic acid and salicylic acid.


PROCEDURE:D. Hydrolysis of an Ester

Dilute 5.0 ml of 6N sodium hydroxide with an equal volume of water in a hard glass test tube. Add 5.0 g of acetylsalicylic acid and heat in a boiling water bath for five minutes. Cool to room temperature and then acidify the mixture with 6N hydrochloric acid until a precipitate is formed. Filter.

1. Basic Ferric Acetate TestTo 1.0 ml of the filtrate obtained from hydrolysis, add 6N sodium

hydroxide until the solution is slightly alkaline to litmus paper. Add ferric chloride dropwise to the solution until a change is noted. Record your observations.

2. Ferric Chloride TestMix a pinch of the residue obtained from hydrolysis with 2.0 ml water. Add

three drops of ferric chloride and note what happens. Record your observation.

Summary of the Hydrolysis of Ester

"The hydrolysis of Ester (ASA/Aspirin) will yield acetic acid and salicylic acid. Acetic acid, together with the filtrate, will react to the ferric ion. Acetic acid will be neutralized and will become Acetate so that Sodium Hydroxide will be the one reduced and not Acetic Acid. Acetate will then react with Ferric Chloride, producing Ferric Acetate which has the visible result present in the experiment.(reddish brown color)."

Basic Ferric Acetate Test

Basic Ferric Acetate Test versus Ferric Chloride Test

• OBJECTIVE• "The primary objective of Basic Ferric Acetate

Test is to test for any presence of ferric ions with the use of Ferrous Acetate and the filtrate. On the other hand, Ferric Chloride Test is used to test for phenols as residue is added."

RESULT OF BASIC FERRIC ACETATE TEST

• VISIBLE RESULT• "An aqueous solution of Basic Ferric Acetate

will yield a reddish brown liquid. The Acetate from the neutralized Acetic Acid will react with the Ferric Chloride, producing Ferric Acetate which is the one responsible for the visible result in the solution."

Ferric acetate is the coordination compound more commonly known

as "basic iron acetate". With the formula [Fe3O(OAc)6(H2O)3]OAc

(OAc is CH3CO2-), it is a salt, composed of the cation [Fe3(μ3-O)

(OAc)6(H2O)3]+ and an acetate anion. The formation of the red-

brown complex has long been used as a test for ferric ions.

Ferric Chloride Test

The ferric chloride test is used to determine the presence or absence of phenols in a given

sample. Enols give positive results as well. The bromine test is useful to confirm the result.

Phenols form a complex with Fe(III), which is intensely colored. This is the basis for the test.The sample is dissolved in water, or a

mixture of water and ethanol, and a few drops of dilute ferric chloride solution is added. The

formation of a red, blue, green, or purple coloration indicates the presence of phenols.

Where the sample is insoluble in water, it may be dissolved in dichloromethane with a small

amount of pyridine.

Lab Report-Introduction to the Ferric Acetate Test

• Acetylsalicylic acid (C6H4OCOCH3COOH) is the ubiquitous pain reliever known as aspirin. Chemically, aspirin is both an aromatic acid and an ester; analgesic properties notwithstanding, the compound is an excellent showcase for at least two or three principles of organic chemistry.

• Salicylic acid (C6H4OHCOOH; aspirin's parent compound) and sodium salicylate (C6H4OHCOONa) are useful for detecting iron compounds; they form colored complexes with the Fe3+ ion. They can also be used in several organic chemistry experiments which illustrate important principles.

• For convenience we may abbreviate acetic acid as HOAc or AcOH. This refers to an acetate group ("OAc"; Figure 1) with a hydrogen ("H"). Acetic acid loses an H+ when it ionizes to acetate, which is then abbreviated as OAc-.

Lab Report-Introduction to the Ferric Acetate Test

• Because the shorthand system becomes ambiguous with more complex molecules, we'll refer to salicylic acid as "SA" and acetylsalicylic acid as "ASA". (Consider that HOSal could be salicylic acid, if we assume the dissociable H+ comes from the carboxylic acid group.)


• Ferric acetate is the coordination compound more commonly known as "basic iron acetate". With the formula [Fe3O(OAc)6(H2O)3]OAc (OAc is CH3CO2-), it is a salt, composed of the cation [Fe3(μ3-O)(OAc)6(H2O)3]+ and an acetate anion. The formation of the red-brown complex has long been used as a test for ferric ions.

•

• Figure 3. Reddish Brown Solution of Basic Ferric Acetate Test• Laboratory Observation: The solution turned reddish brown in color.


• Q: In the basic ferric acetate test, why is it important that the solution be kept neutral? What would happen if there is an excess of acid or alkali?

• A: Acetate would either be oxidized or reduced.


• The ferric chloride test is used to determine the presence or absence of phenols in a given sample. Enols give positive results as well. The bromine test is useful to confirm the result. Phenols form a complex with Fe(III), which is intensely colored. This is the basis for the test.The sample is dissolved in water, or a mixture of water and ethanol, and a few drops of dilute ferric chloride solution is added. The formation of a red, blue, green, or purple coloration indicates the presence of phenols. Where the sample is insoluble in water, it may be dissolved in dichloromethane with a small amount of pyridine.


Figure 4. Purple Solution of Ferric Chloride Test------------------------------------------------------------------------------------------------Laboratory Observation: The solution turns purple in color.

Study Question 5

Q: After alkaline hydrolysis of acetylsalicyclic acid and acidification, what products (filtrate and residue) are formed? Write the equations involved and name the corresponding products.

A: The hydrolysis of acetylsalicyclic acid aspirin will yield acetic acid (residue) and salicylic acid (filtrate).

Study Question 6

Q: What tests proved the identity of the products (filtrate and residue). Give all equations involved and the formulas responsible for the visible results.

A: The Ferric Chloride Test proved the identity of the products, acetic acid and salicylic acid. The Ferric Chloride test showed the presence of the phenol group –OH both the residue and the filtrate which proved that the presence that both are carboxylic acids.

O Cl || | CH3-C-OH + H2O+ FeCl3 -> FeO(OH) + CH3-C-Cl | Cl

Salicylic Acid + FeCl3 -> Iron (III) Salicylate and hydrochloric acid

+ FeCl3 -> Fe(C7H5O3)3 (aq) + 3HCl (aq) 3 C7H6O3 (aq)

Test for Benzoic Acid

Benzoic Acid

Introduction: • Benzoic acid is the simplest aromatic carboxylic

acid. Its chemical formula is C7H6O2 (or C6H5COOH).

• Its structure is of a benzene ring (6-sided ring) and has the following attachment to a carbon on its ring: a carbonyl group and a hydroxyl group.

http://en.wikipedia.org/wiki/File:Benzoes%C3%A4ure.svg

Physical and Chemical Properties of Benzoic Acid

It’s a colorless, crystalline solid. Its melting point is at 122°C and its boiling point is 249°C.

• Solubility: • Benzoic acid is soluble in hot water but in room temperature

water (25°C), its solubility is 0.34 g/100 ml, which means it is insoluble.

• It is soluble in ethanol (2.58M), methanol (2.91M). • • Chemical Properties• Benzoic acid: pka = 4.21

Preparation of Benzoic Acid

Uses of Benzoic AcidBenzoic Acid and its salts are used as food preservatives. One of the salt derivatives is the carboxylic acid salt, benzoate.

http://en.wikipedia.org/wiki/File:Benzoic_acid-chemical-synthesis-1.png

Two possible reactions

• From the lab experiment performed, either one of two reactions can occur:

• The production of a benzamide (if water used was hot enough) or

• The production of a carboxylic acid salt, a benzoate

• To coincide with my lab result, I will discuss the production of a benzoate and thus will proceed to discuss Carboxylic Acid Salts, specifically enzoic Acid.


BENZOIC ACID

Introduction• Benzoic acid is a weak acid, the simplest

aromatic carboxylic acid. Its chemical formula is C7H6O2 (or C6H5COOH). Its structure is of a benzene ring and has the following attachment to a carbon on its ring: a carbonyl group and a hydroxyl group.


BENZOIC ACID-PHYSICAL AND CHEMICAL PROPERTIES

Physical Properties of Benzoic Acid

It’s a colorless, crystalline solid. Its melting point is at 122ºC and its boiling point

is 249ºC.

Solubility:

Benzoic acid is soluble in hot water but in room temperature water (25ºC), its

solubility is 0.34 g/100 ml, which means it is basically insoluble or only slightly

soluble in room temperature water. It is soluble in THF (3.37M), ethanol (2.58M),

methanol (2.91M).

Chemical Properties

Benzoic acid: pka = 4.21

BENZOIC ACID

• Preparation of Benzoic Acid• Commercially, Benzoic acid is produced by the

partial oxidation of toluene with oxygen with one the following catalysts: manganese naphthenate or cobalt.


LAB EXPERIMENT- BACKGROUND

• From the lab experiment performed, either one of two reactions could have occurred if the right conditions were maintained:

• The production of a benzamide (100°C water used) and a dehydrating agent was used.

• The production of a carboxylic acid salt, a benzoate (if the water did not maintain 100°C).

LAB EXPERIMENT-BACKGROUND

As the water was not kept hot enough to produce an amide, the resulting reaction produced a benzoate and therefore, I will proceed only in the discussion of carboxylic acid salts and the “Test for Benzoic Acid” lab experiment.

CARBOXYLIC ACID SALTS

• Carboxylic Acid Salt• A carboxylic acid salt is an ionic compound in

which the negative ion is a carboxylate ion. - Exploring Organic and Biological

Chemistry• Carboxylic acid salts are produced from the

neutralization reaction between a carboxylic acid and a strong base.

LAB REPORT-TEST FOR BENZOIC ACID

• Lab Report: Test for Benzoic Acid

Objective: To test for an aromatic acid, in this lab, it is a test for the presence of a benzoic acid

Reagents used: Benzoic acid

Ammonium Hydroxide (6N NaOH)Ferric Chloride [Iron (III) Chloride]

• Materials/Equipment used: Water bath (hot water)One test tubeGraduated cylinderLitmus paper

Reagents used in Lab experiment Benzoic Acid Ammonium Hydroxide Iron (III) Chloride Ferric (III) Chloride | NH4 OH - a Bronsted-Lowry Base

NH3 + H20 => NH4+ + OH-

Ammonia Water Ammonium Hydroxide ion(Base H+ (Acid H+ ion (basic solution)Acceptor) Donor)

O|| .. C – OH


Procedure: 1) Take 1 test tube and add water (6-7 ml)2) Heat in a hot water bath and after heating, make sure

there is 5ml of water left for the procedure3) Dissolve a “mongo-grain” amount of Benzoic Acid in the

5ml of hot H20

4) Add 6N NH4OH until the solution is neutral or slightly alkaline (test with litmus paper).

5) If it is alkaline, warm until solution is neutral.6) Add 6 gtts of FeCl3 and note what is formed.


• Reaction: A benzoate is formed from a reaction between the weak acid, Benzoic Acid, and the weak base, Ammonium Hydroxide (Brönsted-Lowry Base) and the FeCl3 is used to detect if there is an aromatic acid. The positive test for benzoic acid using FeCl3 will be a precipitate of an orange or tan color.


• Benzoic Acid + Ammonium hydroxide → Ammonium benzoate + Iron (III) Chloride

+ → → + H2O + FeCl3

→ 3 + Fe(OH)3 ↓ + H2O Cl

FERRIC (III) HYDROXIDE IS THE COMPOUND RESPONSIBLE FOR THE ORANGE PRECIPITATE


• Benzoic acid is not soluble in water as it has a benzene ring and therefore does not have free protons (hydrogens) to donate as part of a hydrogen bond. In order to neutralize benzoic acid, ammonium hydroxide is used. The carboxylic acid salts are solids at room temperature and have high melting points. Because they are ionic compounds, carboxylic acid salts of the alkali metals (Li+, Na+, and K+) and NH4+ are usually soluble in water.

• • The Neutralization reaction between the carboxylic acid, Benzoic acid and the base,

Ammonium hydroxide produces a Carboxylic Acid salt, Ammonium benzoate. The Iron (III) Chloride was used to produce a reaction showing the presence of an aromatic acid.

• • RESULT: My lab experiment yielded a rusty orange or tan precipitate in turbid

solution which proves a positive test for benzoic acid.• •

Amides

• Amides are derivatives of carboxylic acid in which the carboxyl –OH group is replaced with an amino group or a substituted amino group ( NH2, NH, N).

Primary Amide Secondary Amide Tertiary Amide

Unsubstituted Monosubstituted Disubstituted amides

Two hydrogen atoms bond to the amide nitrogen atom

An alkyl (or aryl) group and a hydrogen atom are bonded to the amide nitrogen atom

Two alkyl (or aryl) groups and no hydrogen atoms are bonded to the amide nitrogen atoms.

O || R-C-NH2

O O || R-C-NH-R’

O O ||

R-C-N-R’ | R

Physical Properties of Amides

• Amides have a lone pair (nonbonding pair) of electrons which is not vailable for bonding with H+ ions, as Amines do, thus amides do not exhibit the same basic properties of amines.

Benzamide

• A benzamide is a secondary (2°) amide produced from the Amidification Reaction (a Condensation reaction) of a benzoic acid and a primary amine, or in the case of the lab, an ammonia.

Carboxylic Acid Salt

• A carboxylic acid salt is an ionic compound in which the negative ion is a carboxylate ion.

- Exploring Organic and Biological Chemistry

• Carboxylic acid salts are produced from the neutralization synthesis reaction between a carboxylic acid and a strong base.

Lab Report-Test for Benzoic Acid-Part E

Objective: To test for an aromatic acid, in this lab, it is a test for the presence of a benzoic acid

Reagents used: • Benzoic acid• Ammonium Hydroxide (6N NaOH)• Iron (III) Chloride

Materials/Equipment used: • Water bath (hot water)• One test tube• Graduated cylinder• Litmus paper

Lab Experiment-Test for Benzoic Acid

Procedure: 1. Take 1 test tube and add water (6-7 ml)2. Heat in a hot water bath making sure there is 5ml of water left for the

procedure3. Dissolve a “mongo-grain” amount of Benzoic Acid in the 5ml of hot H20

4. Add 6N NH4OH until the solution is neutral or slightly alkaline (test with litmus paper).

5. If it is alkaline, warm until solution is neutral.6. Add 6 gtts of FeCl3 and note what is formed.

In the laboratory iron(III) chloride is commonly employed as a Lewis acid for catalysing reactions such as chlorination of aromatic compounds and Friedel-Crafts reaction of aromatics.

Two different products can be derived from this lab experiment depending on the temperature of the water used. For the purpose of this report, I will

discuss both results.

If hot water (100 °C) water was used during the reaction between the carboxylic acid and an amine, then an amide will be the product.

Product: Ammonium Benzamide (hot water-100°C)If room temperature water (25°C) water was used during the reaction,

then this will be an acid-base reaction producing a carboxylic acid salt.

• Two different products can be produced depending on if the water used was hot or not:

• Product: Ammonium Benzoate (warm water)

Reactions

• Reaction 1: A benzamide is formed from the reaction between the Benzoic acid and the Ammonium Hydroxide and the Iron (III) Chloride [FeCl3) is used as a catalyzing agent.

catalyzing agent.

Hot H2O (100ºC) and FeCl3

-C-OH + NH4OH → -NH2

+ + FeCl3 → + FeO(OH) ↓ + H2O

O || C- NH2

Reactions

• Reaction 2: A benzoate is formed from a reaction between Benzoic Acid and Ammonium Hydroxide (Bronsted-Lowry Base) and the FeCl3 is used to detect if there is an aromatic acid.

• Ferric Chloride Test: For presence of aromatic acid. warm H2O

-C-OH + NH4OH → C7H9NO2

Benzoic Acid + Ammonium hydroxide → Ammonium benzoate

+ → + H2O

Result of Lab Experiment

Yield: A rusty orange precipitate in turbid solution.

carboxylic acids grp 5

Health & Medicine

carbonic acid

nucleic acid

insoluble benzoic acid

benzoic acid c6h5cooh

addition of hydrochloric

benzoic acid solution

solution of acetic acid

acetic acid solution