Using acid base chemistry in the separation of substances can be a quite useful technique in organic chemistry. A basic extraction can be carried out by applying a hot solvent such as water to a dry substance like coffee. This will allow for the extraction of caffeine and flavor from the coffee beans. Acid base chemistry can be useful in separating neutral, basic, and acidic organic substances by controlling the pH of the aqueous layer. In acid base extraction a solvent such as ether is mixed with an aqueous solution of a different pH. This will aid in ionizing the intended compound and separate it from the mixture. Once the molecule is ionized it will precipitate out of the ether solvent and dissolve into the aqueous layer. The aqueous layer can then be removed and the pure substance can be obtained through crystallization.
• Acid-base concept
• Role of this form of titration in pharmaceutical quality assurance
• Ionization
• Low of ionization
• Henderson hasselbarkh equation equation
• Neutralization curves
• Acid-base indicators
• Mixed indicators used in polyprotic & amino acid systems during amino acid titration
• Acid-base concept
• Role of this form of titration in pharmaceutical quality assurance
• Ionization
• Low of ionization
• Henderson hasselbarkh equation equation
• Neutralization curves
• Acid-base indicators
• Mixed indicators used in polyprotic & amino acid systems during amino acid titration
Acid base Theories
Role of the solvents
Acid base dissociation constant,
Relative strength of acids and bases
Distribution of acid base species with pH
Buffer solution
Henderson Hasselbalch equation,
Indicators, Mixed indicators
Different type of titrations (Neutralization curves)
Polyprotic systems,
Phosphoric acid system,
Polyamine and amino acid systems.
Titration of sodium carbonate
Lavoisier definition
Liebig definition
Arrhenius Acids and Bases
Bronsted-Lowry Acid and Base
Lewis Acid and Base
Solvent-system Concept
Lux-Flood Concept
Pearson’s Concept
Historically, the first of the scientific concepts of acids and bases was provided by the French chemist Antoine Lavoisier, circa 1776.
Lavoisier's knowledge of strong acids was mainly restricted to oxyacids, which tend to contain central atoms in high oxidation states surrounded by oxygen, such as HNO3 and H2SO4, and he was not aware of the true composition of the hydrohalic acids, HCl, HBr, and HI. From his limited knowledge,
He defined acids in terms of their content of oxygen, and he named oxygen from Greek words meaning "acid-former"
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Acid base Theories
Role of the solvents
Acid base dissociation constant,
Relative strength of acids and bases
Distribution of acid base species with pH
Buffer solution
Henderson Hasselbalch equation,
Indicators, Mixed indicators
Different type of titrations (Neutralization curves)
Polyprotic systems,
Phosphoric acid system,
Polyamine and amino acid systems.
Titration of sodium carbonate
Lavoisier definition
Liebig definition
Arrhenius Acids and Bases
Bronsted-Lowry Acid and Base
Lewis Acid and Base
Solvent-system Concept
Lux-Flood Concept
Pearson’s Concept
Historically, the first of the scientific concepts of acids and bases was provided by the French chemist Antoine Lavoisier, circa 1776.
Lavoisier's knowledge of strong acids was mainly restricted to oxyacids, which tend to contain central atoms in high oxidation states surrounded by oxygen, such as HNO3 and H2SO4, and he was not aware of the true composition of the hydrohalic acids, HCl, HBr, and HI. From his limited knowledge,
He defined acids in terms of their content of oxygen, and he named oxygen from Greek words meaning "acid-former"
QSAR Inquaries Market will offer curriculum planning, web based software, In class clickers for classroom assessment
QSAR Inquiries Market will offer computer Based Organizational Assessments Performance
Cooperative learning in science education is addressed in this article. How students use a very relevant topic of anti-cancer agents, and the novel technique of (Heteronuclear single Quantum Correllation Spectroscopy )2D -HSQC FT-NMR to organize spectra data is shown. Here, undergraduates become familiar with making plots of 1H FT-NMR and 13C FT-NMR , learning FT-NMR data processing (spinworks) and also use Chemdraw NMR to present data take with a Varian 600 MHz FT-NMR spectrometer.
In this paper, student projects are given as an example on how to introduce FT –NMR into the undergraduate curriculum.
We will incorporate NMR experiments that illustrate the application of high resolution NMR spectroscopy to the structure determination of Anti-Cancer agents.
High resolution 13 C and 1H NMR , 13 C –distortionless enhancement by polarization transfer (DEPT) , 2D 13C-1H correlated (HECTOR), and 2D 1H-1H correlated (COSY) spectroscopy techniques will be used for elucidating skeletal arrangement of monomer units
Most common oxidation state = Bi³⁺
The free ion is strongly hydrolyzed, forming insoluble basic saltsOnly common oxidation state in aqueous systems
Halides, nitrates, sulfate, and acetate of Cadmium are soluble in water
Most cadmium salts are colorless
CdS = Yellow
CdO = Yellow brown
Forms complex ions with common ligands (Halides, CN⁻, NH₃
Acids, Bases And Buffers Pharmaceutical Inorganic chemistry UNIT-II (Part-I)
Acids, Bases are defined by Four main theories,
1.Traditional theory / concept
2.Arrhenius theory
3.Bronsted and Lowry theory
4.Lewis theory
Importance of acids and bases in pharmacy
Buffers: Buffer action
Buffer capacity Buffers system
Types of Buffers : Generally buffers are of two types:
1. Acidic buffers
2. Basic buffers
There are some other buffer system:
3. Two salts acts as acid-base pair. Ex- Potassium hydrogen phosphate and potassium dihydrogen phosphate.
4. Amphoteric electrolyte. Ex- Solution of glycine.
5. Solution of strong acid and solution of strong base. Ex- Strong HCl with KCl Mechanism of Buffer action: Mechanism of Action of acidic buffers: Buffer equation-Henderson-Hasselbalch equation:
Standard Buffer Solutions Preparation of Buffer Solutions: Buffers in pharmaceutical systems or Application of buffer: Stability of buffers Buffered isotonic solution Types of Buffer Isotonic solution
1. Isotonic Solutions:
2. Hypertonic Solutions:
3. Hypotonic Solution:
Measurement of Tonicity: 1. Hemolytic method: 2. Cryoscopic method or depression of freezing point:
Methods of adjusting the tonicity:
Class I methods:
In this type, sodium chloride or other substances are added to the solution in sufficient quantity to make it isotonic. Then the preparation is brought to its final volume withan isotonic or a buffered isotonic diluting solution.
These methods are of two types:
Cryoscopic method
Sodium chloride equivalent method.
Class II methods:
In this type, water is added in sufficient quantity make the preparation isotonic. Then the preparation is brought to its volume with an isotonic or a buffered isotonic diluting solution.
These methods are of two types:
White-Vincent method
Sprowls method.
Non- aqueous titrations are those in which the titrations of too weakly acidic or basic substances are carried out using non-aqueous solvents so as to get sharp end point.
Such titrations can also be used for the titration of the substances not soluble in water.
The speed, precision and accuracy of the non-aqueous method are close to those of classical acidimetric and alkalimetric titrations.
First reported successful quantitative titration of organic acid and base in non-aqueous solvent: 1910.
To an understanding of non-aqueous acid base titrimetry the theories of acid and base is very important. The theories are:
Acids are hydrogen containing compounds that dissociates to yield hydrogen ions (H+) when dissolved in water.
Bases are compounds that dissociates to yield hydroxide/hydroxyl ions (OH-) when dissolved in water.
3. Separation of Acidic Substances
Author: Dr. Robert D. Craig, Ph.D.
• Application:
• Acids and Bases are one the most
fundamental principles of chemistry. Acidity
and basicity are involved in determining
chemical reactivity, separation, solubility, and
transport of molecules across membranes.
4. Background
• Aqueous (water based) solvents are very
polar. Organic solvents are much less polar
than aqueous solvents.
6. Background
• The underlying principle behind acid
extractions begins with the fact that many
neutral organic compounds are not soluble in
water but are soluble in organic solvents. If a
neutral organic compound is converted to an
ion by reaction with a base, then the polarity
of that compound is significantly increased.
7. Background
• . The ion typically has a high solubility in water
and a reduced solubility in the organic solvent.
This often causes the ion to migrate to the
aqueous phase from the organic phase.
8. Get to the point Rob . .
• Benzoic acid –not soluble in water
• But the “sodium salt is”
9. Get to the point . . ..
• In order to separate these compounds, we will
convert the water insoluble acid into a water
soluble salt:
10. Subsequently . . .
• Can use a strong acid to take the salt back to
organic layer soluble acid form
11. Background
• One possible experiment begins with two
neutral organic compounds (benzoic acid and
2-naphthol) dissolved in an organic solvent,
MTBE (methyl t-butyl ether). ####This is
changed (diethyl ether)
12. Diethyl ether instead
A base is added which will selectively react with
one of the materials and convert it into its
conjugate base (an ion). These ions have a high
solubility in water and a low solubility in ether,
so they will migrate (partition) to the aqueous
phase.
13. Like dissolves like
• The aqueous phase is removed along with the
conjugate base of the first compound. This
layer is later acidified, protonating the
conjugate base. The solubility of the neutral
material in water is low, and the compound
precipitates and is recovered by filtration.
14. Not MTBE
• This process is repeated with the addition of a
stronger base to the MTBE which will react
with the second compound and that material
will deprotonate, form an ion then partition to
the aqueous phase.
• Again the aqueous layer is removed, acidified
and the precipitated neutral material is
recovered.
18. Some terminology
• 1. Some terminology related to Acid-base
extractions:
• Acid: In this experiment we are discussing
Bronsted-Lowry acids, hence an acid is a
material that may lose a proton and form a
conjugate base.
HA -> H+ + A-
• The stronger the acid, the weaker the
conjugate base.
19. Some Terminology
• Base: In this experiment we are discussing
Bronsted-Lowry bases, hence a base is a
material that may gain a proton and form a
conjugate acid.
B- + H+ -> HB
• The stronger the base, the weaker the
conjugate acid.
20. Some Terminolgy
• Partitioning: The distribution of a substance or
ions between two immiscible liquids.
• Extractioning: Dissolution and removal of one
constituent of a mixture in a solvent.
• Precipitation: If the concentration of a
compound in a solvent is greater than the
solubility of that compound, the compound
will no longer remain dissolved and will form a
new solid phase
21. Some terminology
• Equilibruium Constant (K): The numberical
value of the concentration of the products
divided by the concentration of the reactants.
If the value of K is smaller than one, the
equilibrium lies in favor of the starting
material. The reaction does not proceed
greatly in the forward direction.
• If the value of K
23. Two phase system, hydrophobic (top) and hydrophilic (bottom)
for measuring the partition coefficient of compounds
24. Some terminology
• pKa: The negative log of the acid equilibrium
constant. pKa= - log Ka where the acid
equilibrium constant Ka is equal to:
The smaller the pKa the stronger the acid
25. Smaller -pKa the stronger the acid.
• 2. Useful pKa information. (Do not memorize
pKa values)
26. Smaller-pKa the stronger the acid. .
ACID (HA) pKa CONJUGATE BASE (A-)
Hydrochloric Acid (HCl) pKa= -7.0 Chloride ion (Cl-)
Benzoic acid (Ph-CO2H) pKa = 4.17 Benzoate ion (Ph-CO2-)
Carbonic acid (H2CO3) pKa = 6.35 Bicarbonate ion(HCO3-)
2-Naphthol pKa = 9.5 2-Naphthonate ion
Water (H2O) pKa = 15.7 Hydroxide ion (HO-)
27. smaller-pKa the stronger the acid. .
• First, identify the acid and the base on both sides
of the arrow.
• Compare the pKa of the acids. Determine if the
stronger acid is on the right or the left of the
arrow.
• If the pKa of the acid on the left, HA1 is a smaller
number (that is, the acid is stronger) than the pKa
of the acid on the right, HA2 then the reaction will
proceed in the forward direction
28. .which way??????
• If the pKa of the acid on the left, HA1 is larger
(that is, the acid is weaker) than the pKa of the
acid on the right, HA2, then the reaction will
not proceed in the forward direction (but it will
proceed in the reverse direction).
30. All possible reactions
• 4. Below are ALL the possible reactions for the lab.
@@@@the handout@@@@@
• Examine each reaction, assign acid
and base to each compound, determine if the reaction
will proceed in the forward
direction or not.
Place an X across each arrow which will not proceed in
the forward
direction. Only write the reactions that WILL proceed in
your lab notebook.
34. @@@@@@@@@@@@@
• 5. Additional structures and information.
• MTBE is Methyl t-Butyl Ether. This compound
is often added to gasoline to increase the
oxygen content and improve the burn
efficiency. MTBE has a density of 0.7404 g/mL
and is less than that of water (density 1.00
g/mL) hence MTBE floats on top of water.
36. SEPARATION OF BENZOIC ACID, 2-
NAPHTHOL, AND 1,4-
DIMETHOXYBENZENE
• Skip to slide 44.
37.
38. • 3. Predicting if a reaction will proceed in the
forward direction or not. To determine if any
acid-base reaction will succeed, as shown,
• HA1 + -A2 → -A1 + HA2
39. • VID 11 FIRST
•
• VID 1
• VID 2
• VID 3
•
• LAB #3: SEPARATION OF BENZOIC ACID, 2-
NAPHTHOL, AND 1,4- DIMETHOXYBENZENE
40. • 6. Aqueous solutions are very polar. Organic
solvents are less polar than aqueous.
• Like materials like other materials like
themselves. Ions are very polar.
• Typically ions have a higher solubility in water
than organic solvents. Most neutral organic
compounds have limited solubility in water
but an increased solubility in organic solvents.
41. • If a neutral organic compound dissolved in an
organic solvent is deprotonated and turned
into an ion, the solubility in the organic
solvent will be decreased and the ion will
want to move or partition into an available
aqueous solvent.
42. IF a base is chosen which will selectively
• deprotante one of a mixture of dissolved
organic compounds and turn only into an ion,
• then mixtures of compounds can be
separated. This concept is why this separation
• experiment is possible.
43. Slide 44
• 7. The two compounds are separated as ions
dissolved in water. It is desired to reform
and isolate benzoic acid and 2-naphthol as
pure solids. In order to do this, a very strong
acid is added to the aqueous solutions, this
will reprotonate the ions and turn
them back into neutral organic molecules.
Most neutral organic compounds have a low
44. • solubility in water. 2-Naphthol and benzoic
acid are not an exception. As neutral
compounds they have a low solubility in the
water, and hence will precipitate as a solid.
The solid is isolated by vacuum filtration. A
melting point will be taken to assess the purity
of these materials
45. • 8. Separatory funnels are specially designed
glassware for the separation of immiscible
liquids. They have a ground glass access port
at the top and a stopcock at the bottom. This
is the most expensive piece of glassware in
your drawers. A new sep funnel costs
approximately $110.00. Handle with care
46. • Prelab.
*Before lab begins, read the following:
Zubrick’s Chapters on Extracting and Washing
(Ch 15 and 16).
Zubrick’s Chapter on Drying Agents (Ch 10).
*Draw the balanced acid-base reactions
including the structures of benzoic acid, 2-
naphthol, and 1,4-dimethoxybenzene and the
products.
47. • *Draw a flow chart of the extraction
procedure.
*Make a table of physical constants and safety
information. Include only relevant data for this
experiment.
48.
49. • http://www.oppapers.com/essays/Separation-Of-
A-Carboxylic-Acid-A/193808
•
•
Grading.
Completion 5 pts
(includes lab and a report turned in on time)
Prelab 3 pts
Experimental 2 pts
Results 5 pts
Conclusion 5 pts