1. QUANTITATIVE DETERMINATION OF ALDEHYDES AND KETONESBY
SRAVAN. S

2. INDEX INTRODUCTION METHODS OF QUNATITATIVE DETERMINATION
SPECTROSCOPIC METHODS
CHROMATOGRAPHIC METHODS

3. Aldehydes and ketones can be determined by using following 3 reagents
Hydroxylamine hydrochloride – Pyridine
Sodium sulphite – Sulphuric acid
2,4 – Dinitro phenyl hydrazine

4. METHOD - 1 Hydroxylamine hydrochloride+carbonyl compounds HCL+OXIME
Pyridine
Pyridine hydrochloride

5. ALDEHYDE H H R-C=O + NH2OH.HCL R-C=NOH + H2O + HCL H H
R-C=O + NH2OH.HCL + C5H5N R-C=NOH + C5H5N.HCL + H2O

6. KETONE R R-C=O+ NH2OH.HCL + C5H5N R-C=NOH+C5H5N.HCL+H2O
C5H5NHCL + NaOH C5H5N + NaCL + H2O

7. The reaction of the carbonyl compound with hydroxyl amine reaches equilibrium which is displaced to the right in presence of pyridine and excess of hydroxyl amine hydrochloride.
The rate of reaction depends upon the structure of –R group,lower aldehydes like and ketones give quantitative reaction in about 30min at room temp, wher as ketone like acetophenone, benzophenone benzoin requires 2hrs heating at 100 degrees centigrade.

8. METHOD-II R-CHO+NaHSO3 RCH(OH)SO3Na
Carbonyl compounds +sodium bisulphate
Crystalline bisulphite
It is determined Iodometrically or by titration
R-CHO+NaHSO RCH(OH)SO3Na

9. METHOD -III O O 2,4-dinitrophenyl hydrazine+carbonyl compound
2,4-dinitrophenyl hydrazone
NHNH2
NO NO2
R R
R-C=O R-C=N-NH NO2
NO2 O O

10. Determination of ketone using 2,4-dinitrophenyl hydrazine
Take 0.2g of camphor in a stopper flask, add 25ml of aldehyde free alcohol to dissolve the sample, with swirling add 75ml of 2,4-dinitrophenyl hydrazine reagent and reflux on a water bath for 4hrs
Remove the alcohol by distillation, cool add 200ml of 2% v/v solution of Sulphuric acid

11. 2,4-dinitrophenyl hydrazone is collected in sintered glass crucible
The ppt is washed with 10ml quantities of water till filtrate is neutral to litmus.
Dry the ppt at 80°c cool and weigh
The percentage of camphor can be calculated by the factor given below
Each gram = 0.458g of camphor
% of camphor = W x x 100
1 x A

12. Determination of Aldehyde by sodium sulphite reagent
250ml of Sodium sulphite solution in a suitable stoppered flask, add 50ml of 1N sulphuric acid
To the above sol add accurately weighed quantity of about mini-equivalent of aldehyde and shake vigorously for 14min.
Intorduce the glass-calomel electrode system in the beaker and connect to pH meter. Titrate the excess of acid with standard 1N alkali solution.
% of Aldehyde = (y-x) x N x M x 100
W x 1000

13. UV-VISIBLE SPECTROSCOPY
The carbonyl group contains a pair of Π electrons and 2 pairs of non-bonding n or p-electrons, in addition to a pair of σ electrons
Saturated ketones and aldehydes exhibit 3absorption peaks .They are
1.Π – Π*
2. n – σ*
3. R - band

14. Carbonyl groups present in aldehydes and ketones have significant effect upon the n-Π* transitions.
The R-band gets shifted to shorter wavelength with a slight change in intensity. The shift in absorption is due to a combination of inductive and resonance effects.
Substitution may change the energy levels of both the ground and excited states

15. INFRARED SPETROSCOPY
A Strong absorption band in the region around 1700 is due to c=o stretching
The carbonyl groups of aldehydes generally absorb at 10-15cm-1higher frequencies than the corresponding ketones.
Thus 3-pentanone shows a c=o stretch at 1715cm-1 ,aliphatic aldehydes absorb near cm-1.

16. Majority of aldehydes show aldehyde C-H stretching absorptions in the region cm-1. Two moderately intense bands at are frequently observed in the region cm-1and diferentiate aldehyde class or compounds from other carbonyl compounds
The important difference between an aldehyde and ketone is there an aldehyde has a H-bonded to the carbonyl compounds.
The important difference b/w an aldehyde and ketone is that an aldehyde has a H-bonded to the carbonyl carbon.

17. The aromatic aldehyde , ex: p-tolualdehyde shows its aldehydic C-H stretch at 2830 and 2736cm-1
The carbonyl stretching frequency of a pure sample of saturated aliphatic aldehyde around 1725cim-1 that of a ketone at 1710cm-1 .

18. IR FREQUENCIES FOR ALDEHYDES AND KETONES
Group/Vibrations Frequencies cm-1
C = O Stretching
Saturated acyclic – 1720
Alpha,beta-unstaurated,
acyclic – 1685
Aryl – 1695
C – H stretching – 2695
C – H bending

19. KETONES:
C =O Stretching
Saturated acyclic – 1705
Alpha,beta unsaturated ,
acyclic – 1665
Aryl – 1665
C – H stretching

20. MASS SPECTORMETRY
Some important features of the mass spectra of aliphatic aldehydes and ketones are
The Intensity of the molecular ion peak decreases as the alkyl chain length increases
The major fragmentation processes are ά and β clevage .
In aldehydes and ketones containing γ-hydrogen atom.McLafferty rearrangement ion is most significant. In an aldehyde, which is not ά-substituted , apeak due to this is fored at m/e 44. It may be base peak.

21. In lower aldehydes, ά- clevage is prominent with retention of clevage on oxygen.
In Aromatic aldehydes and ketones parent ion peak is intense.
In ketones, the loss of larger group is preferred by a ά- clevage.

22. HPLC KETONE: Formulation: Thymol,methylsalicylate,
Camphor and salicylic acid.
Sample preparation: Sample suspended in 100ml of solvent, warmed in water bath(60c) and shaken for 10min. Centrifuged and supernatant used for analysis.
Standard Preparation: Solution of each ingredient is prepared in solvent. [water-THF- methanol]

23. Internal Standard: Diphenhydramine Hcl - 100µg/ml in solvent.
HPLC System: Shimadzu LC system.
Column: Shimpak CLC – DDS Column,
150 x 6mm
Chromatographic conditions: Compositon of mobile phase and its PH: 200mM sodium perchlorate in 10mM sodium phosphate. PH: 2.6 – Methanyl acetonitrile
Flow rate: 1.5ml/min
Volume Injected: 20 µl

24. Wave length: UV – 210nm
Retention time:
Salicylic acid
Diphenhydramine Hcl
Methyl Salicylate
Camphor
Thymol

25. ALDEHYDE
Formulation: Betamethasone valerate, clotrimazole, Benzaldehyde.
Sample Preparation: weigh 0.64mg of Betamethasone or 10mg of clotrimazole, add 2ml of standard solution and 8ml of methanol. Heat in waterbath(60c) for 10min,cool,centrifuge and filter.
Standard Preparation: Betamethasone dipropionate - 320µg/ml
clotrimazole - 5mg/ml
Both the solutions are prepared in methanol, mixed standard solution

26. Column: Suplex PKB – 100 column, 250 x 4.6mm
Conditions: Composition of MP and its PH Acetonitrile – Tetrahydrofuran – 15mm
Acetate buffer – PH – 4
Flow rate: 2ml/min
Volume Injected: 10µl
Wave length: U.V – 254nm
Retention time: Benzaldehyde – 3.3
clotrimazole

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