Identify Carboxylic acids , amines and amino acids

به وبلاگ آزمایشگاه جداسازی و شناسایی ترکیبات آلی خوش آمدید ، امیدوارم مطالب وبلاگ من برای شما مفید باشد

Identify Carboxylic acids , amines and amino acids...

Thin-layer (TLC) is a chromatographic technique that is useful for separating organic compounds. Because of the simplicity and rapidity of TLC, it is often used to the progress of organic reactions and to check the purity of . Method Thin-layer consists of a stationary phase immobilized on a or plastic plate, and an organic . The sample, either or dissolved in a volatile solvent, is deposited as a on the stationary phase. The constituents of a sample can be identified by simultaneously running with the unknown. The bottom edge of the plate is placed in a reservoir, and the moves up the plate by action. When the front reaches the other edge of the stationary phase, the plate is removed from the reservoir. The separated spots are visualized with ultraviolet light or by placing the plate in iodine . The different components in the move up the plate at different rates due to differences in their partioning between the mobile phase and the stationary phase http://www.chemicool.com/definition/thin_layer_chromatography_tlc.html   Producing the chromatogram We'll start with a very simple case - just trying to show that a particular dye is in fact a mixture of simpler dyes Identify Carboxylic acids , amines and amino acids...ادامه مطلب

Sodium metal test Chemical properties Alcohols react with active metals like sodium and liberate hydrogen gas that can be observed in the form of effervescence http://amrita.olabs.edu.in/?sub=73&brch=8&sim=141&cnt=1 http://documents.mx/documents/experiment-8b.html   Physical Properties       The metal melts below the boiling point of water (97oC). In its elemental state it has been used as a molten coolant in nuclear reactors and is currently under research for sodium/sulfur batteries. Its most common compounds for industrial use include sodium chloride, sodium hydroxide (lye), sodium carbonate (washing soda) and sodium sulfate. Color Silver Phase at Room Temperature Solid Density 0.968 g/cm3 Boiling Point 883o C Melting Point 97.72o C           Complications Combined with active hydrogen. This test gives a positive answer     Ceric ammonium nitrate test   Chemical properties Alcohols reacts with ceric ammonium nitrate to form a red coloured alkoxy cerium (IV) compound   http://amrita.olabs.edu.in/? Identify Carboxylic acids , amines and amino acids...ادامه مطلب

Iron(III) Chloride - Pyridine Test Chemical properties Identification of phenols. A. All phenols react with iron(III) chloride solution to form a color compounds. Phenols with one hydroxy group form a violet compounds, phenols with two OH- groups – blue compounds, thymol does not react with iron chloride     (a) Reaction with FeCl3 : Phenol gives violet coloration with ferric chloride solution (neutral) due to the formation of a colored iron complex, which is a characteristic to the existence of keto-enol tautomerism in phenols (predominantly enolic form Physical Properties   Complications – Not all phenols or enols give positive results  Most oximes, hydroxamic acids, and sulfinic acids give a positive test  Bulky groups on the benzene ring, especially inthe ortho position, may cause the experiment to show a negative result  Activating groups attached to the ring decreases the wavelength caused by less electron excitation, thus causing a different color of positive result http://documents.mx/documents/experiment-8b.html       urethane of alcohol      3.5-Dinitrobenzoates of Alcohols   Identify Carboxylic acids , amines and amino acids...ادامه مطلب

2,4-DNP Test for Aldehydes and Ketones   Chemical properties         Carbonyl Group The carbonyl group in aldehydes and ketones reacts with hydrazine and its derivatives. The compound most frequently used is 2,4-dinitrophenylhydrazine because the product is always a solid. When 2,4-DNP is used as a solution it is known as Brady's Reagent. Addition of one or two drops of the suspected carbonyl compound to 1cm3 of Brady's reagent produces a yellow-orange solid http://sustainability.sellafieldsites.com/resources/labmouse/chemistry_a2/2501.php   Physical Properties   Complications Some ketones give oils which will not solidify Some allylic alcohols are oxidized by the reagent to aldehydes and give a positive test Some alcohols, if not purified, may contain aldehyde or ketone impurities   http://academics.wellesley.edu/Chemistry/chem211lab/Orgo_Lab_Manual/Appendix/ClassificationTests/aldehyde_ketone.html         Addition of sodium hydrogensulphite to aldehydes and ketones   Chemical properties The reactions This reaction only works well for aldehydes. In the case of ketones, one of the hydrocarbon groups attached to the carbonyl group needs to be a methyl group. Bulky gr Identify Carboxylic acids , amines and amino acids...ادامه مطلب

 alkyne Bromine in Carbon Tetrachloride Chemical properties Bromine will add to the carbon-carbon double bond of alkenes to produce dibromoalkanes and with alkynes to produce tetrabromoalkanes.  When this reaction occurs, molecular bromine is consumed,  and its characteristic dark red‑brown color disappears if bromine is not added in excess.  The rapid disappearance of the bromine color is a positive test for unsaturation. The test is not unequivocal, however, because some alkenes do not react with bromine, and some react very slowly.  In the case of a negative test, therefore, the potassium permanganate test should be performed Physical Properties   Complications Should be employed in conjunction with Baeyer test (dilute KMnO4 Electron-withdrawing groups in the vinylic position can slow down bromine addition to the point that a negative test is erroneously produced Tertiary amines (like pyridine) form perbromides upon treatment with bromine and lead to false positive tests Aliphatic and aromatic amines can discharge the bromine color without the evolution of HBr gas http://academics.wellesley.edu/Chemistry/chem211lab/Orgo_Lab_Manual/Appendix/ClassificationTests/unsaturation.h Identify Carboxylic acids , amines and amino acids...ادامه مطلب

Carboxylic Acids   Chemical properties Determination of Equivalent Weight (or Neutralization Equivalent) Molecular Weight Determination   Generally, any acid (or base) can be titrated using standard solutions of base (or acid). The neutralization equivalent obtained is usually a simple fraction of the molecular weight (1, 1/2, 1/3, etc). In the titration of an acid with standard base, the endpoint is reached when all the acid is neutralized and a drop of excess base is added. If phenolphthalein is used as the indicator, it will tu red at this instant. For a dicarboxylic acid such as malonic acid, the endpoint is reached when the last of the acid is converted to the carboxylate anion. The neutralization equivalent will be one-half its molecular weight.   CH2 (CO2H) 2 + 2 NaOH ----- CH2(CO2Na) 2 + 2 H2O   Equivalent weights must be done in duplicate and the values obtained should agree within a few percent. If not, do a third determination. The equivalent weight (neutralization equivalent) can be calculated as follows: V (ml) x M (mmol/ml)= wt (mg)/equivalent weight (mg/mequiv); V = volume of standard base used measured accurately to at least 3 significant figures; M= molarity of s Identify Carboxylic acids , amines and amino acids...ادامه مطلب