[3] Carbohydrates | Kiliani Fischer synthesis | Ruff degradation|Chain shortening | Chain lengthning

The Kiliani-Fischer Synthesis involves addition of cyanide ion to an open-chain aldehyde (in the case of aldoses) which is then partially reduced and then hydrolyzed to give a new aldehyde. In the absence of chiral reagents, a mixture of diastereomers will be produced.

The Ruff Degradation- It’s also possible to go in the reverse direction, where an aldose is reduced in length by one carbon. The procedure for going in this direction is called the Ruff Degradation, a procedure that dates back to the late 1890s.

In the first step, the aldehyde is selectively oxidized to a carboxylic acid by bromine (Br2) and water. Note that the secondary and primary alcohols are not oxidized here! The next step involves adding an iron (III) salt [Fe2(SO4)3] with hydrogen peroxide, which involves the loss of carbon dioxide and oxidation of the adjacent C2-OH to an aldehyde:

Video parts
Part 1
   • [1] Carbohydrates | Classification of Carb...  
Part 2
   • [2] Carbohydrates | Open chain structure o...  
Part 3
   • [3] Carbohydrates | Kiliani Fischer synthe...   ( you are watching)

Timestamp
00:00- Conversation of glucose into fructose
5:15- Conversation of fructose into glucose
11:30- Chain lengthning or kiliani Fischer synthesis
18:15- Chain shortening or ruff degradation
20:42- Wohl degradation

#misschemistry #carbohydrates #convertionofglucoseintofructose #convertionoffructoseintoglucose #chainlengthning #kilianifischersynthesis #chainshortening #ruffdegradation #wohldegradation