2-Bromo-1,3-cyclopentanedione

China [CN]

I. Basic Information

Chinese Name: 2-Bromo-1,3-cyclopentanedione

English Name: 2-Bromo-1,3-cyclopentanedione

CAS Number: 2052-01-9

Molecular Formula: C₅H₅BrO₂

Molecular Weight: 193.00 (Calculated: C 31.11%, H 2.61%, Br 41.42%, O 16.58%)

II. Chemical Structure and Characteristics

Structural Analysis: The molecule consists of a cyclopentanedione skeleton (a five-membered ring with a keto group at each of the 1st and 3rd positions). A bromine atom (-Br) is attached to the carbon atom at position 2, forming an α-bromodiketone structure. Key Features:

Two keto groups (C=O) are adjacent to the bromine atom. The strong electron-withdrawing effect enhances the electropositive nature of the carbon at position 2, making the bromine atom highly resilient to leaving. The reactivity is much higher than that of the α-bromo form of the monoketone.

The conjugation effect within the ring (the keto groups are conjugated to the carbon-carbon bond) makes the ring structure relatively stable, but the presence of the bromine atom imparts rich reactivity.

The chiral carbon at position 2 (depending on the ring substituents) may allow for stereoisomers, but due to its symmetric structure, this compound generally exists in a single configuration.