3-4: Organic Analysis

Question 1

How do you test conclusively for primary and secondary alchohols

Answer 1

• oxidise with acidified potassium dichromate
• orange —> green
• test for aldehyde: Fehlings (or Benedict’s)/tollens
• brick red potty/silver mirror
• no change is a ketone

Question 2

How do you test for tertiary alchohols?

Answer 2

• attempt tk oxidised with acidified potassium dichromate
• no change for aldehydes

Question 3

Why do you have to take be careful when testing alchohols?
How can you mitigate the risk

Answer 3

• highly flammable
• use water bath instead of bunsen

Question 4

Describe a test for carboxylic acids:
Why might this test be inaccurate?

Answer 4

• add spatula of sodium carbonate/ solution
• if it begins to fizz, bubble (CO2) gas it produces through lime water
• turns cloudy
• gives positive result with any acid

Question 5

Describe a test for alkenes/unsaturation

Answer 5

• shake with bromine water
• orange—> colourless

Question 6

How/why does IR spectroscopy work?

Answer 6

• IR radiation passed through chemical
• absorbed by covalent bonds, increasing their vibrational energy
• different bonds and positioning of bonds absorb differentfrequencies of IR radiation
• impacts IR mass spec

Question 7

What is the fingerprint region

Answer 7

• section of IR spec unique to each molecule

Question 8

Describe an O-H carboxylic acid peak on an IR mass spec

Answer 8

• medium broad peak (lower wave number than alchohol O-H)

Question 9

Describe a C=O peak on an IR mass spec

Answer 9

• strong, sharp absorbtion peak at around 1720cm^-1

Question 10

Describe a C-H peak on an IR mass spec

Answer 10

• Sharp, shallow peak around 3000cm^-1 (genetic)

Question 11

Describe an N-H peak on an IR mass spec

Answer 11

• very deep, broad peak at about 3350 cm^-1

Question 12

Describe an O-H alchohol peak on an IR mass spec

Answer 12

• strong, broad peak (higher wave number than carboxylic acids)