Why does glucose heated with HI produce n-hexane?

[erisedk]

Why does glucose on prolonged heating with HI give n-hexane?
What mechanism/reaction type is this? All I knew till now was that alcohols would give halogen substituted products with hydrogen halides.

 

[DrDu]

It's a reduction with hydroiodic acid being oxidized to iodate. Btw the same reaction is used in the synthesis of methamphetamine in beeaking bad.

 

[erisedk]

Is it a common mechanism in introductory organic chemistry?