VOLATILE OILS

Volatile Oils

➢ Also known as Ethereal Oils or Essential Oils or Essences.

➢ Easily evaporates at a room temperature

➢ They are generally complex products composed of mixtures of compounds of widely variant chemical characteristics

Spot test

to differentiate volatile oil and fixed oil. Fixed oil leaves a stain or grease in a filter paper. Volatile Oil leaves no visible spot or mark in a filter paper.

▪ Flavorants

▪ Perfuming Agent

▪ Counterirritants

Common uses of volatile oils

▪ Ester content

▪ Alcohol content

▪ Aldehyde content,

▪ Ketone content

▪ Phenol content

The purity of volatile oils are definitely established by the determination of chemical constants such

Hydrocarbons of the isocyclic series

e.g. pinene, camphene, limonene, bornylene, fenchene, dipentene, sylvestrene and phellandrene.

Alcohols

linalool, geraniol, citroneol, terpineol, borneol, menthol and santalool.

Aldehydes

benzaldehyde, cinnamic aldehyde, salicylic aldehyde, citral and citronellal

Ketones

camphor, carvone, fenchone, thujone and menthone.

Phenols

anethol, eugenol, carvacrol, saffrol and chavicol.

Acids

acetic, propionic, butyric, valeric, benzoic, cinnamic and hydrocyanic acids

Esters

linalyl acetate, bornyl acetate and menthyl acetate

Sulfur compounds

such as allyl isothiocyanate

▪ Mustard Oil

▪ Malodorous or foul odor

Specific Gravity

Determined by the westphal balance or pycnometer

0.84 to 1.2

Specific gravity values ranges from

orange, caraway, coriander, lemon, turpentine and rosemary oils.

Oils lighter than water are:

anise, cinnamon, clove, sassafras oils

Oils heavier than water include:

Relative density

computed by the ratio of the density of substance over the density of standard (H2O - 1g/mL)

Pycnometer

Official method in USP in determining the specific gravity

heavier than H2O

Specific Gravity > 1

lighter than H2O

Specific Gravity < 1

25°C

temperature used in determining the specific gravity

Rotary Power

Measured by polarimeter.

Optically Active Compound

Chiral Molecules

▪ Ability of a sample to contain plain polarized light

Abbe Refractometer

Most commonly used instrument in Refractive index is the

1.46 to 1.61 at 20°C

Refractive index values ranges from

Refractive index

Measure of refracting ability of the sample.

▪ Ability of a liquid to bend light

Distilling Range

The lower limit of the range is the temperature indicated by the thermometer when the first drop of condensate leaves the tip of the condenser, and the upper limit is the temperature at which the last drop evaporates from the lowest point in the distillation flask

Distilling Range

Temperature at which the volatile oil distills

NLT 95% distills between 250°C - 255°C

Eugenol distills at

Fractional Distillation

determines possible presence of alcohol and petroleum ether which distills or boils below 100°C.

soluble

Generally, volatile oils are _________ in organic solvents

Steam distillation

Isolation of volatile oils is done through

condenser

is combined with the receiver to avoid as much as possible the loss of volatile oil vaporization and to provide direct reading of the volume of the oil.

4-8 hours

How many hours is steam distillation of volatile oils conducted

alc. KOH

Assay for Ester Content

Esters are refluxed with ____, saponified and yield the free alcohol and the potassium salt of the acid

peppermint oil

Alcohol content of peppermint oil

Borneol

Alcohol content of rosemary oil

Bisulfite Method

is based on the principle that the aldehydes and ketones found in volatile oils form soluble addition products with sodium bisulfite and that these products being soluble in water leave a certain volume of oil which do not contain aldehydes or ketones

Sodium Bisulfite (NaHSO3)

Reagent of Bisulfite Method

Bisulfite Method

Limited only for the assay of volatile oils which do not contain constituents other than aldehyde and ketones which react with sodium bisulfite

Hydroxilamine Hydrochloride (NH2OH HCl)

Reagent of Hydroxylamine Method

Bromophenol Blue TS

Indicator of Hydroxylamine Method

Formation of Light Green

Endpoint of Hydroxylamine Method

Phenol Content

Applies similar principle with bisulfite method

Phenol Content

The method and principle is identical to the bisulfite method for the assay of aldehyde and ketones except that the solution used is either sodium or potassium hydroxide.

phenols

Volatile oils that contain ______ when shaken with solution of potassium hydroxide/sodium hydroxide diminish in volume because of the steady solubility of the phenol constituents in alkali leaving the non-phenolic portion of the oil undissolved

Spirits

A type of liquid dosage form wherein they are characterized as alcoholic solutions of volatile solutions

Volatile Oil Spirit

Dissolved in an alcoholic solvent, usually ethyl alcohol or ethanol

immiscible solvent (kerosene) and measuring the volume of the liberated oil.

Solvent used for the assay for volatile oils in spirits

Bobcock bottle

Bottle used in the assay of volatile oil in spirits