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lassaigne extract
A small piece of sodium is heated gently in an ignition tube till the sodium melts. About 50 to 60 mg of the organic compound is added to this and the tube heated strongly for 2-3 minutes to fuse the material inside it. After cooling, the tube is carefully broken in a china dish containing about 20 to 30 mL of distilled water. The fused material along with the pieces of ignition tube is crushed with the help of a glass rod and the contents of the china dish are boiled for a few minutes. The sodium salts formed in the above reactions (i.e. NaCN, Na2S, NaX or NaSCN) dissolve. Excess of sodium reacts with water to give sodium hydroxide. This alkaline solution is called Lassaigne's extract or sodium extract. The solution is then filtered to remove the insoluble materials and the filtrate is used for making the tests for nitrogen, sulphur and halogens.
ReactionsAn organic compound containing C, H, N, S and halogens when fused with sodium metal gives the following reactions.
(NaSCN) is formed during fusion, which in the presence of excess sodium forms sodium cyanide and sodium sulphide.
Detection of nitrogenA small quantity of the sodium extract is taken in a test tube. It is made alkaline by adding 2-3 drops of sodium hydroxide (NaOH) solution. 1 mL of freshly prepared solution of ferrous sulphate is added to this solution. The mixture of the two solutions is boiled and then acidified with dilute sulphuric acid. The appearance of prussian blue or green colouration of the precipitate confirms the presence of nitrogen in the given organic compound. The carbon and nitrogen present in the organic compound on fusion with sodium metal give sodium cyanide (NaCN) soluble in water. So, the sodium extract contains sodium cyanide which, on reaction with ferrous sulphate, gives sodium ferrocyanide. Some of the ferrous salt is oxidised to the ferric salt on heating and this reacts with sodium ferrocyanide to form ferric ferrocyanide.
Note: When nitrogen and sulphur both are present in any organic compound, sodium thiocyanate is formed during fusion. When extracted with water sodium thiocyanate goes into the sodium extract and gives 'blood red coloration' with ferric ions due to the formation of ferric thiocyanate.
Detection of sulphurThe presence of sulphur in any organic compound is detected by using sodium extract as follows:
Lead acetate testA small portion of sodium extract is acidified with acetic acid and lead acetate solution is added to it. A black precipitate of lead sulphide indicates the presence of sulphur.
Sodium nitroprusside testTo a small quantity of sodium extract taken in a test tube, 2 to 3 drops of sodium nitroprusside are added to the solution. A violet color indicates the presence of sulphur. This color fades away slowly on standing.
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What is Lassaigne's extract?
Lassaigne test is a method in qualitative analytical chemistry used to detect halogens, sulfur or nitrogen in organic compounds.
Is acetaminophen will give positive result to Lassaigne's test and ferrox paper test?
yes
How do you get the extract the atis leaf?
extract it
How do you extract acrylonitrile?
hoe do u extract acrolnitrile
What is the major ingredient for the british foodstuff marmite?
The major ingredient for the foodstuff Marmite is yeast extract. The extract is a by-product of beer production. Similar products include Vegemite, Cenovis, and Vitam-R.
What is Lassaigne's extract?
Lassaigne test is a method in qualitative analytical chemistry used to detect halogens, sulfur or nitrogen in organic compounds.
Why only sodium is used in Lassaigne's test?
because of its electropositive nature. it is cheap also. although potassium can be used but it is costly... and lithium is less electropositive... Lassaigne's test is a test for the detection of halogens, nitrogen and sulphur in an organic compound. These elements are covalently bonded to the organic compounds. In order to detect them, these have to be converted into their ionic forms. This is done by fusing the organic compound with sodium metal. The ionic compounds formed during the fusion are extracted in aqueous solution and can be detected by simple chemical tests. The extract is called sodium fusion extract or Lassaigne's extract.
Mechanism of lassaigne's test?
Name alternative method for lassaigne's test
When was Jean Louis Lassaigne born?
Jean Louis Lassaigne was born on 1800-09-22.
What has the author J Lassaigne written?
J. Lassaigne has written: 'Spanish painting from Velazquez to Picasso' 'Spanish painting from the Catalan frescos to El Greco'
When did Jean Louis Lassaigne die?
Jean-Louis Pons died on October 14, 1831 at the age of 69.
How do you prepare cashew bark extract?
make tea out of it and expect a fall in blood sugar level
Why is ferric ferrocyanide prussian blue in lassaignes test?
Prussian test is a part of lassaigne test, since prussain test used for nitrogen detection while lassaigne used for detection of halogens sulphur and nitrogen in organic compounds
Is acetaminophen will give positive result to Lassaigne's test and ferrox paper test?
yes
Can a person get drunk from almond extract?
Yes. Almond Extract, Anise Extract, and Lemon Extract have high alcohol content (60%-80%) You can get drunk off of it, but it will taste horrible. Prepare to be in extreme discomfort after drinking.
Does hydrazine answer the test for nitrogen in Lassaignes test?
lassaigne's test is not given by hydrazine as it cannot produce NaCN
Why is it necessary to prepare sodium extract for the detection of foreign elements?
We need to prepare sodium extract for the detection of foreign elements because foreign elements are found in organic compound bonded covalently. As a result they cannot be detected through organic compound directly. Hence they are first converted into ionic compound with the help of sodium extract
