ex 8 methyl salicylate

methyl salicylate

also known as wintergreen oil or betula oil

methyl salicylate

an ester volatile oil that has a characteristic flavor and odor (minty)

salicylic acid

precursor of methyl salicylate

maceration and subsequent steam distillation

methyl salicylate can be produced naturally by ___

wintergreen leaves

Gaultheria procumbens

SWEET BIRCH TREE BARK

Betula lenta

MEADOWSWEET LEAVES

Filipendula ulmaria

Auguste André Thomas Cahours

methyl salicylate was first isolated from the plant Gaultheria procumbens L. in 1843 by the French chemist ___

methyl salicylate

an ester of salicylic acid and methanol

• rubefacient in deep heating liniments to treat joint and muscular pain

• counter-irritant

• analgesic

use of methyl salicylate in high concentration

• flavoring agent in chewing gum and mints (0.04% and below)

• provides fragrance in other products

• odor-masking in some pesticides

use of methyl salicylate in low concentration

liniment

(methyl salicylate) efficascent oil

ointment

(methyl salicylate) katinko

liniment

(methyl salicylate)omega pain killer

cream

(methyl salicylate) ben-gay pain relieving

patch

(methyl salicylate) salonpas pain relief

embrocation

(methyl salicylate) white flower

7; 23

a single teaspoon (5 mL) of methyl salicylate contains _ g of salicylate, which is equivalent to more than __ 300 mg aspirin tablets

N&V, hyperventilation and tinnitus

salicylism

-

methyl salicylate can also cause skin irritation and skin rashes

salicylic acid

limiting reactant for syntheis of methyl salicylate

salicylic acid

reacts with methanol in the presence of sulfuric acid to form methyl salicylate

methanol

salicylic acid reacts with __ in the presence of sulfuric acid to form methyl salicylate

ester group

salicylic acid reacts with methanol in the presence of sulfuric acid to form methyl salicylate

the carboxylic acid group is replaced with __ upon reaction

salicylic acid

15.2 g

ilang grams ung ginamit na salicylic acid

36ml

ilang ml ung ginamit na methanol

water

• the methyl group of the methanol attaches to carboxylate ion forming an ester

• the hydroxyl group forms bond with H+ producing __

3.5ml

ilang ml ung ginamit na concentrated sulfuric acid

conc. sulfuric acid

used as catalyst to accelerate the reaction of salicylic acid with methanol

Petroluem Ether

used to extract the methyl salicylate

organic solvent(like petroleum ether)

• methyl salicylate is more soluble in __; other components in the mixture especially if very polar, will be drawn into water

• the aqueous layer is drained, leaving the organic solvent where the methyl salicylate is dissolved

• removed from the mixture by steam bath

steam bath

petroleum ether is removed from the mixture by __

20% sodium carbonate

used to remove the unreacted salicylic acid

20% sodium carbonate

it reacts with salicylic acid to form sodium salicylate with carbon dioxide as a by-product

carbon dioxide

sodium carbonate reacts with salicylic acid to form sodium salicylate with as __ a by-product

-

• sodium carbonate is used to remove the unreacted salicylic acid

• it reacts with salicylic acid to form sodium salicylate with carbon dioxide as a by-product

• the ionic sodium salicylate would drawn into the aqueous layer (soluble) and can be removed from the extraction mixture

anhydrous magnesium sulfate

used to remove the remaining water in the mixture of the organic solvent (petroleum ether) and the desired product (methyl salicylate)

anhydrous magnesium sulfate

it acts as a drying agent, dehydrating the mixture leaving the organic layer free from water and other water-soluble impurities

salicylic acid, methanol, sulfuric acid

synthesis of methyl salicylate

• __ are mixed all together in an Erlenmeyer flask

• boiling chips are added to prevent bumping of solution

• solution is refluxed for 1 hour

1 hour

synthesis of methyl salicylate

• salicylic acid, methanol, sulfuric acid are mixed all together in an Erlenmeyer flask

• boiling chips are added to prevent bumping of solution

• solution is refluxed for __

deprotonated

Fischer Esterification

• the carboxylic group of the salicylic acid is __ and the methyl group from the methanol reacts to form an ester, which is the methyl salicylate

• reaction is catalyzed by sulfuric acid

Fischer Esterification

reaction in synthesis of methyl salicylate

ice bath; petroleum ether; distilled water; 20% sodium carbonate

extraction in synthesis of methyl salicylate

• after heating, solution is cooled in an __

• __ is used to extract the methyl salicylate

• __ is added to wash off polar compounds

• __ is added to remove excess unreacted salicylic acid

anhydrous magnesium sulfate

drying & filtration in synthesis of methyl salicylate

• extract is dried using __

• it is then filtered in a pre-weighed evaporating dish

• solvent is removed using steam bath

• methyl salicylate is weighed, and percentage yield is computed

ester + water

salicylic acid + methanol =

anhydrous magnesium sulfate

synthesis of methyl salicylate

Removing water formed by adding a drying agent like __ to the reaction mixture. This shifts the equilibrium to the right.

• color: clear colorless or slightly yellowish

• odor: minty (wintergreen odor)

• appearance: oily, slightly viscous liquid

physical test of methyl salicylate (color, odor, appearance)

hydroxamic acid

ester + hydroxylamine (1ml) =

maroon

esters when heated with hydroxylamine produce hydroxamic acids that reacts with ferric ion to form intensely colored complexes, commonly dark __ in color

ferric hydroxamate test

related to the phenol test wherein compounds with high enolic character gives colored complexes with ferric ion

no color/ clear faint yellow

a preliminary test must be performed to check if compound produces enough enol to form colored complexes with ferric ion (continue if __ color only)

__

esters do not form colored complex with ferric ion in the preliminary test

oil of wintergreen, betula oil, gaultheria oil

methyl salicylate synomyms

Methyl-2-hydroxybenzoate

IUPAC name of methyl salicylate

C8H8C3

molecular formula of methyl salicylate

152.15 g/mol

molecular weight of methyl salicylate

222C

boiling point of methyl salicylate

-8.6C

melting point of methyl salicylate

methyl salicylate

0.07 g per 100 mL water at 20°C

solubility of methyl salicylate

1.184g/cm3

density of methyl salicylate

sensitive to light and heat

stability of methyl sallicylate

phenol with an attached ester group on ortho position

structure of methyl salicylate