pharchem ii postlabs

POST-LABS

Pharmaceutical Organic Chemistry

FUNCTIONAL GROUP

• ALIPHATIC • AROMATIC• ALCOHOL• CARBOXYLIC ACID• AMIDES• AMINES

• ALDEHYDES• KETONE• ESTERS• ETHERS

FUNCTIONAL GROUP

SALICYLIC ACID C7H6O3aka as____________

10 mL of Oil of wintergreen+

200 mL 25% NaOH Reflux distillation Cool and + HCl

Salicylic acid

Salicylic acid

Other method

• Sodium salicylate is by treated with sodium phenolate with carbon dioxide at high pressure (100 atm) and high temperature (390K) -a method known as the Kolbe-Schmitt reaction.

Chemical Formula

• Salicylic acid C7H6O3• Me Salicylate C8H8O3• Sodium Hydroxide NaOH• Hydrochloric acid HCl

Chemical Reactions

Theoretical Yield

DENSITY Volume Mass MW2.13 g/ mL 200 mL =1.17 g/ mL 10 mL =

TY=( MW of the Product) ( Wgt Reactants) MW of the Reactants

Solution for Theoretical Yield


=

= _____?

Percent Yield

Percent Yield= Actual Yield X 100 Theoretical Yield

Eg. Actual yield: 3 g

= = ___?

Physical Properties

• Color = white• Odor = odorless• Appearance = crystalline powder• Melting Point = 158-161 C

Chemical Properties

Reagents ResultBromine water white ppt (Tribromophenol-

bromide)

Ferric Chloride soln Violet solution

Methyl Alcohol Irritating/ pungent odor(forms and ester and water)

Conclusion

• Salicylic acid can be done…..• It has it own physical and chemical

properties….

Answers to Questions

1. What chemical group can you attribute the color change of salicylic acid with Ferric chloride soln?

Phenol group= monohydroxybenzoic acid

+ purple, blue, red or green color

Structure of SA

2. What are the pharmaceutical and medicinal uses of salicylic acid?

Anti-septic pain relieverKeratolytic Fever ReliefAnti-fungal


Products with Salicylic acid

3. What is the difference between natural and synthetic salicylic acid?

Natural SA (wintergreen leaves, sweet birch bark, willow bark)

Synthetic SA (synthesize in the lab)+ Natural SA does not have negative effects


4. What are the major chemical classes of salicylates in medicine?

USESSalicylic acid = keratolytic/ antisepticSodium salicylate = analgesic/

antipyreticAcetyl SA = analgesic/ antipyreticMe Salicylate = liniment


5. What pharmacologic category do drugs containing SA belong to?

Salicylates = NSAID


METABOLISM of SA

• SA glucosyltransferase converts SA toIts metabolite SA glucoside.

Synthesis of Acetylsalicylic acid 3 g of Salicylic acid + 6 mL acetic anhydride

+ 85% phosphoric acidHeat 10 mins in beaker

Distilled water+ 20 mL water then COOL

Scratch the walls of the flask, filter, washThe crystals, filter, then oven dry

WEIGH

Preparations with ASA

• Salicylic acid - C7H6O3• Acetic anhydride - C4H6O3• Phosphoric acid - H3PO4• Ferric Chloride - FeCl3• Sodium hydroxide - NaOH

Sulfuric acid - H2SO4• Acetic Acid• Acetylsalicylic acid

Chemical Formula

Chemical reaction

Theoretical Yield

DENSITY Volume Mass MWSA 1.443 g/cm3 3gAcetic 1.082 g cm3 6 mL




=

= _____?

Percent Yield


Eg. Actual yield: 2.5 g

= = ___?

Physical Properties

• Color = white• Odor = odorless• Appearance = crystal figures• Melting point = 135C

Chemical Properties

Reagents ResultFerric Chloride Violet colored soln

Sodium hydroxide Yield water and Na salicylate

Ethanol, sulfuric acid Yield water andMe Salicylate

Chemical reaction

In conclusion:

• Acetylsalicylic acid can be done…..• It has it own physical and chemical

properties….

Structure of ASA


1. Give the products of Aspirin hydrolysis.

2. Why is the salt form used in place of the original acetsalicylic acid in dosage from formulation?

- Salts of ASA are unstable in pharmaceutical dosage forms.


3. Give the different therapeutic uses of acetylsalicylic acid?

- NSAID indicated for fever and pain (RA, Reiter’s syndrome, Osteoarthritis) and inflammation in the body.

- Prevents blood clots (stroke to occur, heart attacks)


4. What are the side effects of acetylsalicylic acid?

- Gastrointestinal effects (stomach ulcerations, abdominal burning, pain, cramps, nausea, gastritis and bleeding)

- Tinnitus- Liver toxicity- Others: Rash, vertigo, dizziness, kidney

impairment.


5. What are the conditions that lead to gastric mucosal irritation of acetylsalcylic acid?

- Alcohol intake- Corticosteroids- Pyrazolone derivatives (phenylbutazone)- Ibuprofen


6. What is the storage requirement for salicylic acid?

Store at room temperatue.Away from moisture and lightDo not use if ASA has vinegar smell.


Metabolism of Acetylsalicylic acid

• Glucuronidation• Active metabolite : Salicylate

Synthesis of Methyl salicylate

60 mL methanol + 27.6 Salicylic acidH2SO4, swirlreflux 2 hrscool in iced bath

20% sodium carbonate(50 ml of hexane, 5 minutes)

Drain off the aqueous layer from funnelWash hexane soln with

Water, drain soln containSodium salt of SA

Dry hexane soln with Mg sulfateThen, evaporate in fume hood

Synthesis of Methyl salicylate

Chemical Formula

• Salicylic acid - C7H6O3 • Methanol - CH3OH • Hydrochloric acid - HCl• Hexane - C6H14• Magnesium SO4 - MgSO4• Sulfuric acid - H2SO4• Ferric Chloride - FeCl3• Me Salicylate -

Chemical Reaction

Theoretical Yield

DENSITY Volume Mass MWSA 1.44 g/cm³ 3gAcetic 1.08 g/cm³ 6mLASA 1.40 g/cm³




=

= _____?

Percent Yield


Eg. Actual yield: 20 g

= = ___?

Physical Properties

• Color = white• Odor = odorless• Appearance = crystalline powder• Melting Point = 135 C

Chemical Properties

Reagents ResultFerric Chloride Violet colored soln

Sodium hydroxide Yields water andNa salicylate

Ethanol, H2SO4 Yields water and Me salicylate

Structural of Methyl SA

Answers to Questions:

1. What is the mechanism of methyl salicylate formation?

Carboxylic acid + alcohol = ester & water.

2. What are the natural sources of methyl salicylate?

Pyrotaceae Family, Pyrola genus , Gaultheria genus

Wintergreen


3. What method is used in the extraction of methyl salicylate from plants?

Steam distillation to extract essential oilsWintergreen is purified thru application of

steam.Maceration is performed to isolate the

essential oil (Me Salicylate)


4. What is the use of methyl salicylate? Give examples of its preparation available in the market?

Rubefacient in deep heating liniments.Flavoring agentsOdor masking agent


Products with Me Salicylate

6. Why is the internal use of methyl salicylate limited to small quantities only?

Can induce vomiting Severe fetal poisoning

Symptoms: tinnitus, NV, swelling, convulsion, kidney failure, dizziness, drowsiness and fever.


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