Ethylene glycol is the common name for the compound with the structure

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Ethylene glycol is the common name for the compound with the structure: HOCH2CH2CH. What is the IUPAC name for this compound?

A) 1,2-diethanol

B) 1,2-phenol

C) propanol

D) dihydroxyethane

E) 1,2-ethanediol

The Correct Answer and Explanation is :

The correct IUPAC name for the compound with the structure HOCH2CH2CH is E) 1,2-ethanediol.

Explanation:

Ethylene glycol, commonly known by its common name, is a simple diol (a molecule with two hydroxyl (-OH) groups). To determine the IUPAC name, we need to break down the molecular structure and understand the rules of IUPAC nomenclature:

  1. Structural Analysis:
    The structure provided is HOCH2CH2CH. This represents a three-carbon chain with hydroxyl groups attached at the two ends of the chain. This chain can be recognized as a derivative of ethane (C2H6), with two hydroxyl groups (-OH) substituted at the 1st and 2nd positions.
  2. IUPAC Naming:
  • The parent chain consists of two carbon atoms, forming an ethane backbone.
  • The functional groups present are hydroxyl (-OH) groups.
  • The two hydroxyl groups are attached at positions 1 and 2 on the ethane chain.
  • The term “diol” is used for a molecule containing two hydroxyl groups.
  • The prefix “ethane” comes from the two-carbon backbone, while “diol” indicates the presence of two hydroxyl groups.
  • The positions of the hydroxyl groups are specified by the numbers “1,2” indicating that the hydroxyl groups are on the first and second carbons of the chain.

Thus, the correct IUPAC name is 1,2-ethanediol, which directly reflects the structure of the compound.

Why the other options are incorrect:

  • A) 1,2-diethanol: While this name suggests the presence of two ethanol molecules, it is not in proper IUPAC format. “Ethanol” refers to a different compound, and it should not be used to describe a molecule with a chain like this.
  • B) 1,2-phenol: “Phenol” refers to a benzene ring with a hydroxyl group. This structure is entirely different, so this option is incorrect.
  • C) Propanol: Propanol refers to a three-carbon alcohol with a single hydroxyl group, which doesn’t match the structure of this compound (which has two hydroxyl groups).
  • D) Dihydroxyethane: Although it correctly identifies the presence of two hydroxyl groups, it lacks specificity about the position of the hydroxyl groups on the ethane chain. Therefore, it is less precise than “1,2-ethanediol.”

Thus, 1,2-ethanediol is the correct and most precise IUPAC name.

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