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Quantitative Tests For Identifying Organic Functional Groups.

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Introduction

QUANTITATIVE TESTS FOR IDENTIFYING ORGANIC FUNCTIONAL GROUPS Introduction: Aldehydes and ketones can undergo a variety of reactions, but they share many chemical properties with other related compounds such as acids and esters. It is possible to detect the presence of an aldehyde or ketone by reaction with 2,4 dinitrophenylhydrazine this test only gives a positive result with aldehydes and no reaction with ketones, nevertheless carry out the tollen's reagent to find out whether the ketone is present. Alcohols are hydrocarbons with -OH replacing one or more hydrogen atoms. Alcohols have physical properties intermediate between those of hydrocarbons and water. Depending on where the - OH group appears, alcohols are classified as primary (1 o) [on a carbon attached to only one other carbon], secondary (2 o) [on a carbon attached to two other carbons], or tertiary (3o)[on a carbon attached to three other carbons]. It is important that test tube is dry in order to carry out a test of finding out the presence of OH group, since water contains an -OH group and can therefore produce fumes of HCl which would invalidate the test. As the addition of phosphorus pentachloride is not a specific test for alcohols only. The usual oxidising agent is acid. K2Cr2O7 which turns from orange to green (Cr3+). The reactions involve the loss of the hydroxyl hydrogen together with a hydrogen atom from the adjacent alkyl group. ...read more.

Middle

Skin is stained yellow on contact which can be followed by dermatitis. If dust or solution gets in eyes: Flood the eye with gently running tap water for 10 minutes. Seek medical attention. If spilt on skin or clothes: Brush off as much solid as possible. Flood affected area with large quantities f water. Remove contaminated clothing, sock and rise repeatedly. PHOSPHORUS (V) CHLORIDE CORROSIVE This solid causes burns. Severe irritations. If dust or liquid gets in eyes: Flood the eye with gently running tap water for 10 minutes. Seek medical attention. If spilt on skin or clothes: quickly brush off any solid. Flood affected area with large amount of water. Remove contaminated clothing. SILVER NITRATE CORROSIVE Causes burns. If spilt on skin or clothes: Flood the eye with gently running tap water 10 minutes. Seek medical attention. IRON (iii) CHLORIDE IRRITANT Irritating to the eyes and skin. If left unattended can cause severe burns to the eyes. If solution is spilt on skin or clothes: Remove contaminated clothing. Wash affected area thoroughly . POTASSIUM DICHROMATE TOXIC If contact with the skin it causes irritation If split on skin or clothes: Brush off as much solid as possible. Flood affected area with large quantise of water. Remove contaminated clothing, soak and rinse repeatedly until no yellow colour remains in water. PHENOL TOXIC Toxic in contact with skin, causes burns If spilt on skin or clothes: Flood the eye with gently running tap water 10 minutes. ...read more.

Conclusion

* Observe the reaction. Expected observation Observation with a positive test: CO2 gas which turns lime water milky. * Test 5 for ester: Detailed method: * In a test tube add a spatula load of the unknown. * Add 3 drops of concentrated sulphuric acid. * Add 1cm3 of ethanoic acid. * Place the test tube in a hot water bath for ten minutes. * Pour out onto a beaker with cold water, then smell cautiously. * Observe the reaction. Expected observation: Observation with a positive test: Insoluble layer which floats on water and sweet 'gluey' smell. * Test 6 for phenol: Reactions of neutral iron (iii) chloride Preparing the reagent: To a solution of iron (iii) chloride add sodium carbonate solution dropwise until a faint precipitate of iron (iii) hydroxide is obtained. This then becomes neutral iron (iii) chloride. If too much sodium carbonate is added, iron (iii) chloride solution may be added to the mixture until only a faint precipitate remains. Detailed method: * To about 1g of the unknown add the neutral iron (iii) chloride solution until no further colour change, if any, occurs. Expected observation: Observation with a positive test: a violet colour, this colour is probably due to a complex of Fe3+ with phenol. Book title Author Chapter Page number Year published Advanced chemistry (organic and inorganic) Philip Mathew 116 786 1992 Chemistry 2 Advanced sciences Brian Ratcliff Helen Eccles 3 25 2001 Chemistry Palgrave foundation Rob Lewis Wynne Evans 18 332-339 2001 Chains/rings Brian Ratcliff 1 2,51,67 1996 Organic chemistry, energetics and equilibrium Brian Chapman Alan Jarvis. ...read more.

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