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CA1 - Org chem functional grps > Qualitative tests in Organic Chemistry > Flashcards

Qualitative tests in Organic Chemistry Flashcards

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1
Q

Classification tests FOR UNSATURATION

A
  • Bromine Test for Multiple Bonds
  • Baeyer Test
  • Ignition Test for High Degrees of Unsaturation
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2
Q
  • Reagent: solution of bromine in methylene chloride
  • Test for: Alkenes and Alkynes
  • Positive Result: Discharging of the bromine color without the evolution of hydrogen bromide gas

NOTE: Should be employed in conjunction with Baeyer test (dilute KMnO4).

A

Bromine Test for Multiple Bonds

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3
Q
  • Reagent: solution of potassium permanganate + acetone
  • Test for: Alkenes and Alkynes
  • Positive Result: disappearance of the KMnO4’s purple color ; appearance of a brown suspension of MnO2
A

Baeyer Test for Multiple Bonds

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4
Q
  • Reagent: Heat a small sample on a spatula.
  • Test for: Aromatic rings
  • Positive Result: sooty yellow flame (aromatic ring or other centers of unsaturation)
A

Ignition Test for High Degrees of Unsaturation

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5
Q

Classification tests FOR ALDEHYDES AND KETONES

A
  • Brady’s Test
  • Tollen’s Test
  • Jones Oxidation Test
  • Iodoform Test
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6
Q
  • Reagent: 2,4-dinitrophenylhydrazine reagent
  • Test for: Aldehydes and Ketones
  • Positive Result: Formation of a precipitate
A

Brady’s Test

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7
Q
  • Reagent: Silver Nitrate + Sodium Hydroxide + Ammonia
  • Test for: Aldehydes
  • Positive Result: Formation of silver mirror or a black precipitate
A

Tollen’s Test

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8
Q
  • Reagent: Chromic acid + Sulfuric Acid
  • Test for: Aldehydes
  • Positive Result:
    > production of an opaque suspension with a green to blue color (aldehydes and primary or secondary alcohols)
    > no visible reaction within 2 seconds, the solution remaining orange in color. (tertiary alcohols)

Disregard any changes after 15 seconds.

A

Jones Oxidation Test

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9
Q
  • Reagent: Iodine solution + Sodium Hydroxide + Water
  • Test for: Methyl ketones
  • Positive Result: Formation of solid iodoform (yellow) is a positive test.

(Iodoform can be recognized by its odor and yellow color and, more securely, from the melting point 119o-123oC).

A

Iodoform Test

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10
Q

Classification tests FOR ALCOHOLS

A
  • Jones Oxidation Test
  • Lucas Test
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11
Q
  • Reagent: Chromic acid + Sulfuric Acid
  • Test for: Primary and Secondary Alcohols
  • Positive Result:
    > production of an opaque suspension with a green to blue color (aldehydes and primary or secondary alcohols)
    > Tertiary alcohols give no visible reaction within 2 seconds, the solution remaining orange in color
A

Jones Oxidation Test

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12
Q
  • Reagent: Lucas Reagent (HCl + ZnCl2)
  • Test for: Secondary and Tertiary Alcohols
  • Positive Result: Appearance of a cloudy second layer or emulsion

> 3o alcohols: immediate to 2-3 minutes
2o alcohols: 5 -10 minutes
1o alcohols: no reaction

test applies only to those alcohols soluble in the reagent (monofunctional alcohols lower than hexyl and some polyfunctional alcohols.) This often means that alcohols with more than six carbon atoms cannot be tested.

A

Lucas Test

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13
Q

Classification tests FOR ALKYL OR ACYL HALIDES

A
  • Silver Nitrate in Ethanol Test
  • Sodium Iodide in Acetone Test
  • Beilstein’s Test
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14
Q
  • Reagent: 1% ethanolic silver nitrate solution
  • Test for: Alkyl or acyl halides
  • Positive Result: Formation of a precipitate

NOTE: Carboxylic acids have been known to react in this test, giving false positives.

A

Silver Nitrate in Ethanol Test

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15
Q
  • Reagent: 15% solution of sodium iodide in acetone
  • Test for: Alkyl or acyl halides
  • Positive Result: white precipitate indicates the presence of halides
A

Sodium Iodide in Acetone Test

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16
Q
  • Reagent: Heat the tip of a copper wire
  • Test for: Alkyl or acyl halides
  • Positive Result: green flash is indicative of chlorine, bromine, and iodine

fluorine is not detected because copper fluoride is not volatile.

A

Beilstein’s Test

17
Q

Classification tests FOR CARBOXYLIC ACIDS

A
  • Sodium Bicarbonate Test
18
Q
  • Reagent: methanol + saturated solution of sodium bicarbonate
  • Test for: carboxylic acids
  • Positive Result: Evolution of a carbon dioxide gas
A

Sodium Bicarbonate Test

19
Q

Classification tests FOR PHENOLS AND NITRO GROUPS

A
  • Ferric Chloride Test
  • Ferric Chloride - Pyridine Test
  • Ferrous Hydroxide Test
20
Q
  • Reagent: water or water-alcohol mixture + 1% aqueous ferric chloride solution
  • Test for: Water-soluble phenols
  • Positive Result: red, blue, green, or purple color is a positive test.

This is a less sensitive test for phenols.

A

Ferric Chloride Test

21
Q
  • Reagent: 1% solution ferric chloride in methylene chloride + a drop of pyridine
  • Test for: Water-insoluble phenols (or less-reactive phenols)
  • Positive Result: Addition of pyridine and stirring will produce a color if phenols or enols are present.

This is a more sensitive test for phenols.

A

Ferric Chloride - Pyridine Test

22
Q
  • Reagent: ferrous ammonium sulfate + alcoholic potassium hydroxide
  • Test for: Nitro (–NO2) group
  • Positive Result: formation of the red-brown precipitate of ferric hydroxide
A

Ferrous Hydroxide Test

23
Q

Classification tests FOR AMINES

A
  • Carbylamine Test
  • Azo-Dye Test
  • Nitrous Acid Test
  • Hinsberg Test
24
Q
  • Reagent: alcoholic KOH + chloroform
  • Test for: primary amines
  • Positive Result: confirmed by the release of a foul smell

aliphatic and aromatic primary amines respond to this test. However, secondary and tertiary amines do not give this test

A

Carbylamine Test

25
Q
  • Reagent: sodium nitrite + nitrous acid + HCl followed by Beta-naphthol + Diluted NaOH
  • Test for: aromatic amines
  • Positive Result: red-orange dye confirms the presence of aromatic amines
A

Azo-Dye Test

26
Q
  • Reagent: benzene sulfonyl chloride
  • Test for: distinguishing a primary, secondary, and tertiary amine
  • Positive Result:
  • Primary amine: No reaction or precipitation occurs in the case of primary amines. On adding concentrated hydrochloric acid insoluble substance is visible.
  • Secondary amines: Precipitate in the test tube but do not dissolve in concentrated hydrochloric acid.
  • Tertiary amines: Precipitate in the test tube but dissolve in concentrated HCl.
A

Hinsberg Test

26
Q
  • Reagent: sodium nitrite + nitrous acid + HCl
  • Test for: distinguishing aliphatic and aromatic primary, secondary, and tertiary amines
  • Positive Result:
  • Primary aliphatic amines - result into evolution of nitrogen gas, which is seen as bubbles.
  • Secondary amines - result into formation of a yellow, oily nitrosamine.
  • Tertiary amines - form soluble nitrite salts.
A

Nitrous Acid Test

CA1 - Org chem functional grps (2 decks)

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