9-membered

Thân thiện

A chemist draws the structure of a 9-membered ring compound on a whiteboard.

Definition

1. Adjective:
   • Having a ring structure composed of nine atoms: The term "9-membered" specifically describes a chemical compound whose molecular structure contains a single ring formed by exactly nine atoms. These atoms can be of the same or different elements, typically carbon, oxygen, nitrogen, or sulfur.

Usage

• The adjective "9-membered" is used almost exclusively in scientific contexts, particularly in organic chemistry and pharmacology, to classify and describe cyclic compounds. It is a precise, technical descriptor.
• It is typically placed before the noun it modifies (e.g., "a 9-membered ring") or used predicatively (e.g., "The lactam ring is 9-membered").

Examples

• Attributive use (before a noun):
  • The researchers synthesized a novel 9-membered heterocycle.
  • Azonane is a simple example of a 9-membered cyclic amine.
• Predicative use (after a linking verb):
  • The macrocyclic core of the antibiotic is 9-membered.
  • This specific ring in the molecule is 9-membered, while the other is six-membered.

Advanced Usage

• The term is part of a systematic naming convention for ring sizes. Similar terms include "5-membered," "6-membered," "7-membered," etc.
• The properties of a ring, such as its stability, reactivity, and three-dimensional shape (conformation), are heavily influenced by its size. A 9-membered ring is considered a medium-to-large ring and often exhibits specific conformational strain and flexibility compared to smaller rings.

Variants and Related Words

• Nine-membered: A less common but semantically identical variant.
• Cyclononane (n): The specific hydrocarbon with a ring of nine carbon atoms (C₉H₁₈).
• Medium-ring compound: A broader category that often includes 8- to 11-membered rings.

Synonyms

• Nonatomic (adj): Extremely rare and technical; meaning "having nine atoms." However, this is not standard and "9-membered" is the universally accepted term for ring systems.
• Nine-atom ring: A descriptive phrase with the same meaning.

Notes on Meaning

• The term refers strictly to the number of atoms in the ring, not the number of members in a group or committee. In non-scientific contexts, "nine-member" (usually hyphenated) would be used for that purpose (e.g., a nine-member panel).
• The focus is on the ring structure itself. A molecule may contain multiple rings of different sizes; "9-membered" describes only the specific ring in question.

Học thuật

Adjective

1. of a chemical compound having a ring with nine members

Từ đồng nghĩa

• nine-membered