qualitative organic analysis n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Qualitative organic analysis PowerPoint Presentation
Download Presentation
Qualitative organic analysis

Loading in 2 Seconds...

play fullscreen
1 / 31

Qualitative organic analysis - PowerPoint PPT Presentation


  • 137 Views
  • Uploaded on

Qualitative organic analysis. Reactions of alkanes with bromine. Alkane layer. Water. Alkanes decolourise bromine in the light. But not in the dark!. Reactions of alkenes with bromine. Alkenes decolourise bromine in both the dark and the light. .

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Qualitative organic analysis' - dutch


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide2

Reactions of alkanes with bromine.

Alkane layer

Water

Alkanes decolourise bromine in the light.

But not in the dark!

slide3

Reactions of alkenes with bromine

Alkenes decolourise bromine in both the dark and the light.

reactions of alkenes with potassium manganate vii
Reactions of alkenes withpotassium manganate (vii)

Alkenes decolourise acidified manganate (vii)

Manganese is reduced from purple +7

To colourless +2

slide5

If there is insufficient alkene…

the intermediate brown Manganese (iv) is formed.

slide6

Reactions of alkanes with manganate (vii)

Alkanes do not decolourise acidified manganate (vii) as they are saturated.

slide7

Reactions of haloalkanes with silver nitrate

Chloroalkanes give a white ppt, which darkens to purple on exposure to bright light.

Silver nitrate is colourless

slide8

Reactions with silver nitrate

Bromoalkanes give a buff ppt, which darkens on exposure to bright light.

Silver nitrate is colourless

slide9

Reactions with silver nitrate

Iodoalkanes give a light yellow ppt, which is not photo sensitive.

Silver nitrate is colourless

slide10

Alcohols give effervescence with sodium

This is because they are extremely weak acids.

Hydrogen gives a “pop” with a lighted splint.

slide12

Reactions with sodium dichromate.

Sodium dichromate is an oxidising agent, ie it oxidises other chemicals, being reduced in the process.

Orange chromium (vi) is reduced to

green chromium (iii) when heated with acid.

slide13

Oxidation of primary alcohols.

Primary alcohols are oxidised as orange chromium (vi) is reduced to

green chromium (iii) when heated with acid.

Two organic products are possible; Aldehydes or Carboxylic Acids.

slide14

Oxidation of aldehydes.

Aldehydes are oxidised as orange chromium (vi) is reduced to

green chromium (iii) when heated with acid.

Only one organic product is possible; a Carboxylic Acids.

slide15

Oxidation of secondary alcohols.

Secondary alcohols are also oxidised as orange chromium (vi) is reduced to

green chromium (iii) when heated with acid.

Only one organic product is possible; a Ketone.

slide16

Oxidation of tertiary alcohols

Tertiary alcohols cannot be oxidised by acidified potassium dichromate.

To oxidise them a much stronger oxidising agent is needed that can break C/C bonds.

slide17

Testing for carbonyl compounds.

Both aldehydes and ketones give an orange/red precipitate with 2,4 dinitro phenyl hydrazine.

slide18

Distinguishing between aldehydes and ketones.

Aldehydes are oxidised as orange chromium (vi) is reduced to

green chromium (iii) when heated with acid.

Only one organic product is possible; a Carboxylic Acids.

slide19

Distinguishing between aldehydes and Ketones

Ketones cannot be oxidised by acidified potassium dichromate.

To oxidise them a much stronger oxidising agent is needed that can break C/C bonds.

slide20

Reaction with Fehling’s Solution

Aldehydes change the colour of Fehling’s Reagent upon heating from blue to red.

Blue copper (ii) ions are reduced to red copper (i).

Cu 2++ e- → Cu+

slide21

Ketones do not react with Fehling’s Solution as they are not oxidised by mild oxidising agents.

slide22

Reaction with Tollen’s Reagent

Aldehydes react with Tollen’s Reagent (ammonical silver solution), depositing a silver mirror on the side of the tube.

Silver ions are reduced to metallic silver.

Ag+(aq) + e- → Ag(s)

slide24

Reactions of carboxylic acids

Acids react with metals giving hydrogen.

Carboxylic acids react with sodium, producing effervescence.

Hydrogen gives a “pop” with a lighted splint.

slide25

Reaction of carboxylic acids with sodium carbonate.

Acids react with carbonates to give a salt, water and carbon dioxide.

Effervescence (CO2)

Phenols and alcohols are weaker acids and will not react.

slide26

Reactions with Universal Indicator

Alcohols, carbonyl compounds and esters are neutral so turn Universal Indicator green.

slide27

Alcohols might react with sodium like acids, but…

they are unable to neutralise bases.