Chapter 20, Problem 66A

Interpretation Introduction

Interpretation: The structure of 2,3,4,5,6-pentahydroxyhexanal needs to be drawn.

Concept Introduction: Alkanes are the saturated hydrocarbons which are mainly composed of C and H atoms. The carbon atoms are bonded in straight chain or branched chain. Alkyl halides are the halogens derivatives of alkanes. They have certain heteroatoms as Cl, I, Br or F along with C and H atoms.

The IUPAC rules are purposed to names different alkanes and alkyl halides.

Answer to Problem 66A

  

Explanation of Solution

According to IUPAC rule:

• Root word will be determined on the basis of number of C atoms in the longest chain.
• The primary suffix must be determined on the basis of covalent bonds between carbon atoms of the parent chain. They can be −ane, -ene and −yne.
• The secondary suffix indicates the presence of functional group in the molecule.
• The prefix in the IUPAC name indicates the presence of side chain or certain groups like halogens.

In 2,3,4,5,6-pentahydroxyhexanal, the root word is hex thus there must be 6 C atoms in the parent chain with −CHO as main functional group ( secondary suffix is −al) and 5 −OH groups are bonded from C-2 to C-6 therefore the structure must be:

  

Conclusion

The systematic name is written as follows:

Systematic name = Prefix + Root word + primary suffix + secondary suffix