جلسه پنجم شناسایی استر و تست هیدروکسامیک اسیدEN

Identification esters 

Esther prepare responses

1. Favorskii Reaction Ring

-conntraction2

passerini Reaction3

Physical and chemical properties Esters

1) ethers boiling temperature is much lower than the boiling temperature corresponding acids cause a substituent group RO - with HO - Ability to create hydrogen bonding disappears Hence ester molecules are simple molecules.

esters of the acids are more stable against heat

 ethers due to lack of hydrogen bonds in water less but better than Acids dissolve in organic solvents

.astrha of organic solvents are best

astrha are fragrant compounds found in many fruits are essential

Preliminary tests

4 drops of the unknown liquid in 3 ml of water or ethanol solution and 3-2 drops of 5% solution of ferric chloride in water 
The physical properties of the test 
If the answer is no resonance with primary colors and we can do Hydrvksamyd test. But if orange, red, blue, violet, purple, green or cherry red create the test is positive preliminary test is useless Hydrvksamyd

Hydroksamyd acid test

When esters with hydroxyl Hydrvksamyk test will be converted to the corresponding acid Hydrvksamyk 
Hydrvksamyk acid with ferric ion complexes are stable and color 
Methods: Two to three drops of liquid ester, or about 40 mg of solid polyester in a mixture of a hydroxyl amine hydrochloride 0.5 ml of normal (95% ethanol solution) and 0.2 ml of N6 hydroxide resolve. Boil the mixture for a few minutes. Solution cool and then add 2 ml of a normal hydrochloric acid. If the solution was opaque, 2 ml of 95% ethanol clear to add a comment. Then a drop of 5% solution of ferric chloride and the color that has been created to add the note. If the color of the disappeared continue to increase in ferric chloride color stable. The red color is due tothe positive test

                                   

                                         

                                  

physical properties

 

 

https://en.wikipedia.org/wiki/Hydroxamic_acid 

Attention 

Acyl halide and hydroxyl acid esters Batbdyl reaction Hydrvksamyk to live

Physical properties

The color is Qrmzalbalvyy

Chemical properties

When esters with hydroxyl amine are heated to become Hydrvksamyk corresponding acid

Hydrvksamyk acid with ferric ion complexes are stable and color

complication

1.tdady acids are testing positive answer. 2.trkybat primary and secondary nitro, nitrile and imide number of hope and more aldehydes are no hydrogen alpha to test positive answer. 3.tst hope for a positive solution is red, the color is yellow-brown sediment test is negative. 4. Preliminary tests should be performed before the main test. If you change the color of the original test can not be done with ferric chloride as impurities that may be present in the environment that reacts with ferric chloride is red.

Hydroxamate

Esters can be converted into hydroxamic acids by reaction with hydroxylamine hydrochloride. The hydroxamic acid derivatives form red or violet complexes with aqueous ferric chloride. Phenols also give colored complexes with ferric chloride so an unknown compound must be tested first with ferric chloride before reaction with hydroxylamine to eliminate this possibility

physical properties

 

 

refference

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جلسه هشتم کروماتوگرافی لایه نازکEN

solid - liquid and principles such as chromatography columns. But in this case the object solid adsorbent as a thin layer on a piece of glass or sturdy plastic broadcast.A drop of the solution or the unknown sample is placed near the edge of the screen and the screen are placed in a container with a sufficient amount of solvent extraction.The amount of solvent should be enough to reach the spot just below the surface (Figure A). Solvent goes to the top and mix components at different speeds is gone.As a result of the spots may appear on the screen. These spots are on a line perpendicular to the surface of the solvent container ).

                          

This chromatography is very easy and quickly done. This method is particularly useful for separating components of a mixture and also can be used to determine the best extraction solvent used for column chromatography. 

In TLC The solids that can be used in chromatography   Column will be used, and the silica and alumina is used. Consultants absorbent body with a small amount of preservative such as orthopedics plaster, calcium sulphate or starch are mixed to find the necessary adhesion absorbent body and stick to the list. Pages can be obtained before taking or plastic sheeting on the market is ready to be used.

   

One of the clear advantages of TLC It requires a very small amount of sample. In some cases up to 10 ^-9 g can be detected. The sample size may reach up to 500 micrograms. Drawing on the experience of countless examples can be used. The experience of different spots shave and wash with a suitable solvent (extract). And to identify (through spectroscopy) to use. 

Detection of color spots in the chromatogram is easy and there are several ways to locate a colorless bodies spots.For example, ultraviolet light radiation to the stain, fluorescence properties are determined combinations.Other methods include absorbent body with a fluorescent substance mixed with an inert else. When ultraviolet light shines on this page, the spots objects that absorb ultraviolet light, but no fluorescence properties of the fluorescent screen to appear dark. In many other cases, the detector Reagents others. Such indicators can be unraveled and stains appear on the chromatogram.Sulfuric acid, which many organic compounds into coal conversion and a solution of potassium permanganate Examples of detection reagents that are used in this way.Iodine is also introduced another detector is used. In this case the dose container is placed an environment saturated with iodine vapor. Many organic compounds absorb iodine, and their spots on the chromatogram of color (usually brown) information.

 

In certain circumstances speed combination to slow the progression of solvent (R _f ) Certain properties of the composition. To determine the distance of the object from the starting line to the middle of the stain has come and measure the distance traveled by the solvent they split. This measure distances with the same starting line.

Uses

 

REFRENSE

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