Extraction Lab (Midterm)

Terpenes are a general class of compounds which are composed from units of ___. Often in multiples of 5.

Isoprene

In steam distillation, the volatile oils distill along with the water and separate as they ___ back into the liquid phase.

Condense

More benign approach of extraction is the ues of liquid carbon dioxide or super critical carbon dioxide. Super critical fluid is a form of matter that is neither__ or ___ but __.

Liquid or gas, but has properties of both.

Liquid-liquid two-phase extraction involves partitioning compounds between ___. The classic two phases are __ and __.

Immiscible liquid phases (mutually insoluble). Aqueous and organic.

A variant of liquid-liquid extraction is the separation of different functional groups: __ can react with acids to form a salt, separating into the __. Then you can use an aqueous workup to reform the base.

Bases. Aqueous phase.

__ was converted to a salt by aqueous sodium bicarbonate (NaHCO3) or sodium hydroxide (NaOH).

p-toluic acid

p-toluic acid was converted into a salt by __ or __.

Aqueous sodium bicarbonate (NaHCO3) or Sodium hydroxide (NaOH).

__ is converted into a salt by aqueous NaOH but NOT NaHCO3.

p-tert-butylphenol

p-tert-butylphenol is converted into a salt by __ but NOT __.

aqueous NaOH but NOT NaHCO3.

Acetanilide is a __ __ __ that __ be converted to a salt in aqueous solution.

Neutral functional group, cannot be converted

Using sequential extraction with __ then __, one can separate the three component organic mixture.

Aqueous NaHCO3, then aqueous NaOH.

The liquid-liquid extraction depends on the __ __ of different compounds in the two liquid phases.

Different solubilities

An organic compounds in the presences of two immiscible solvents, like water and diethyl ether, will split in two phases: the __ __ are in the __ __ __ and the __ __ are in the __ __.

Organic compounds are in the diethyl ether phase and the ionic salts are in the aqueous phase.

This is a __ __. Two phases identified by compound density, but the aqueous layers are usually __ than organic layers.

Separatory funnel. Denser.

The big one is a __ __ and the small one is a __ __.

Buchner funnel. Hirsch funnel.

Buchner and Hirsch funnels are used for __ __ to separate the solid from __ __.

Vacuum filtration. Undesirable liquid

Recrystallization __ an organic solvent. The crystals grow into molecules in __ __ __ __ __.

Purifies. Tightly packed repeating lattice structure.

The desired organic solid is in a liquid mixture, __ __ by __ __ (ice bath) induces crystallization.

Lowering solubility by decreasing temperature

For gas chromatography, a mobile phase (an __ __) passes through the column at a controlled flow rate, and the injected samples are carried by the __ __ and __ as they emerge from the outlet.

Inert gas. Mobile phase and detected.

Compounds travel through the column at __ __ because they exist in equilibrium between the stationary and mobile phases, with different equilibrium constants for each compound.

Different rates

Compounds that stick more strongly with the __ __ __ take __ to get through the column.

Liquid stationary phase take longer

__ __ is the most important property for separation with GC.

Boiling point

__ __ molecules will come out of the GC __ if the compounds’ boiling points are similar.

Less polar. First.

A __ of p-toluic acid formed.

Precipitate.

Essential oil and Terpene features:

Produced via biosynthesis by plants and animals in nature. Attractive or defensive secretions. Valued for medicinal properties, flavors, fragrance.

Citrus oils are primarily which terpenes?

(R)(+) limonene / D-limonene

Disadvantages of steam distillation:

Essential oil is vaporized with steam then condensed. Oxidation in moist air converts limonene to carvone / limonene to terpinene. Heating with an acid converts limonene to terpinene. Energy intensive.

Disadvantages of pentane extraction:

Break up matric, mixes with pentane, filter insolubles, evaporate pentane. Volatile and flammable. Difficult to remove from products.

Four standard terpenes:

(R)(+) limonene. Myrcene. y-terpinene. (-) a-pinene.

Liquid CO2 based on __ __ extractions of the terpenes.

Supercritical fluid.

Green Chemistry - Prevent Waste

To avoid producing waste, no need for treatment or cleanup.

Green Chemistry - Atom Economy

Incorporate all atoms from starting materials into products.

Green Chemistry - Low Toxicity

Design alternative processes/substances known to have lower toxicity.

Green Chemistry - Efficacy with low toxicity

Maintain function while lowering toxicity

Green Chemistry - Minimize Auxiliary Agents

Avoid solvents or separation agents whenever possible

Green Chemistry - Energy Efficiency

Minimize impacts by working at ambient temperature and pressure

Green Chemistry - Renewable Feedstocks

Avoid depleting natural resources whe able

Green Chemistry - Fewer Synthetic Steps

Avoid unnecessary derivatization (ie. adding protecting groups)

Green Chemistry - Catalytic Processes

Use of superior efficiency relative to stoichiometric

Green Chemistry - Innocuous after use

Avoid products which persist after use, and are unsafe after degradation

Green Chemistry - In-process monitoring

Control processes in real time, prior to formation of hazardous materials

Green Chemistry - Avoid accident prone materials

Avoid possibility of release, explosion, fire

Pentane replaced with __ in our extraction.

Liquid CO2

Why is supercritical CO2 better for extraction? (green chemistry)

Nonpolar organic solvent, nonflammable, readily available, nontoxic, able to be removed from product; recaptured and reused

Terpenes are __-__ organics that are __ in organic solvent, like pentane or liquid CO2.

Non-polar. Soluble.

Principle of Separations (extraction)

Break matrix, mix with liquid CO2, filter of insoluble materials (rest of peels), evaporate liquid CO2

Phases of CO2

Usually solid (dry ice) or gas. Above 5 atm = liquid. Above critical point = supercritical fluid

Cylinder use:

Protection in case the tube ruptures. Do not place anything above the cylinder with liquid CO2 present, contents under pressure.

Gas chromatography

Different compounds A and B travel through column, can associate with mobile and stationary phase in equilibrium process.

K value for gas chromatography

K = A_{stationary(liquid)}/ A_mobile(gas)

Gas chromatograph definition

Instrument used

Gas chromatogram definition

Plot of detector response (y-axis) versus time (x-axis), with peaks as a function of time

Injection port and gas inlet: introduce sample, vaporize, mix with carrier gas (He)

Column: where separation occurs, contains stationary phase (liquid attached to inert solid)

Detector: creates electronic signal when compounds emerge from column

Output chromatogram

Retention time (x-axis) can determine identity of compound by comparison with a known sample

Integration of chromatogram

Area under the peak = amount of compound present

Retention time

Time from injection point (t=0) to sample peak

Distribution coefficient (K) when liquid phases are immiscible

Concentration of X in organic solvent / concentration of X in aqueous solvent

Equation mechanism of part B (with sodium bicarbonate - NaHCO3)

Salt product in aqueous phase with NaHCO3

Mixture with p-toluic acid, p-tert-butylphenol, and acetanilide + aqueous NaHCO3

p-toluic acid salt in aqueous layer (NaHCO3), p-tert-butyl phenol and acetanilide in organic layer

p-toluic acid salt + HCl and vacuum filtrate

Neutral p-toluic acid precipitate

Organic layer with p-tert-butylphenol and acetanilide + aqueous NaOH

p-tert-butylphenol salt in aqueous layer (NaOH), liquid acetanilide in organic layer

p-tert-butylphenol salt + HCl and vacuum filtration

Neutral p-tert-butylphenol solid

Organic layer with liquid acetanilide + MgSO4 and rotovap

Water removed from solution, rotovap removes solvent; solid organic acetanilide

Incorrectly labeled samples from acid-base extraction Lab 2, how can they be identified?

Solubility in NaHCO3 and NaOH. Melting point. Smell (NO). IR spec. NMR (BEST)