Question

Among the common inhaled anesthetics are: Halothane \(\left(\mathrm{CF}_{3} \mathrm{CHClBr}\right)\) Isoflurane \(\left(\mathrm{CF}_{3} \mathrm{CHClOCHF}_{2}\right)\) Enflurane \(\left(\mathrm{CHFClCF}_{2} \mathrm{OCHF}_{2}\right)\) Methoxyflurane \(\left(\mathrm{CHCl}_{2} \mathrm{CF}_{2} \mathrm{OCH}_{3}\right)\) Draw Lewis structures of these molecules.

Short answer

Draw Lewis structures with carbon centered, following the octet rule for each atom.

Step-by-step solution

Draw Lewis Structure for Halothane

Start with Halothane: \(\mathrm{CF}_3\mathrm{CHClBr}\). Here, carbon is the central atom. Attach a \(\mathrm{CH}\) group to one carbon, three fluorine atoms \(\mathrm{F}_3\), one chlorine \(\mathrm{Cl}\), and one bromine \(\mathrm{Br}\) to complete this molecule. All bonds should satisfy the octet rule where possible.

Draw Lewis Structure for Isoflurane

For Isoflurane: \(\mathrm{CF}_3 \mathrm{CHClOC} \mathrm{HF}_{2}\). The structure includes a \(\mathrm{CF}_3\) group attached to a \(\mathrm{CHCl}\) group. The \(\mathrm{O}\) atom is bonded to another \(\mathrm{CHF}_{2}\) group. Follow the octet rule ensuring all lone pairs and bonding pairs are included.

Draw Lewis Structure for Enflurane

For Enflurane: \(\mathrm{CHFClCF}_{2} \mathrm{OCHF}_{2}\). Begin with a carbon chain \(\mathrm{CF}_2\mathrm{ClC}\), where the \(\mathrm{O}\) connects to a \(\mathrm{CHF}_{2}\) group. Each carbon should comply with the octet rule, adding lone pairs to \(\mathrm{O}\) as necessary to complete the structure.

Draw Lewis Structure for Methoxyflurane

Lastly, Methoxyflurane: \(\mathrm{CHCl}_{2} \mathrm{CF}_{2} \mathrm{OCH}_3\). Construct by placing \(\mathrm{CF}_{2}\) linked to an \(\mathrm{OCH}_{3}\) group, and \(\mathrm{CHCl}_2\) on the other side of \(\mathrm{C}\). Ensure octet completion with the addition of lone pairs and connection of atoms.

Key concepts

Inhaled Anesthetics

Inhaled anesthetics are important compounds used in medical settings to facilitate surgical procedures by inducing unconsciousness or a lack of sensation. These compounds are typically volatile liquids or gases and are administered through inhalation, affecting the central nervous system to provide their anesthetic effects. Common examples include Halothane, Isoflurane, Enflurane, and Methoxyflurane. Each of these compounds consists of different atoms such as carbon, fluorine, chlorine, bromine, and oxygen arranged in specific structures. Understanding the Lewis structures of these anesthetics helps in comprehending their molecular interactions and properties.

• Halothane: Contains a combination of carbon, fluorine, chlorine, and bromine.
• Isoflurane and Enflurane: Incorporate an oxygen atom, contributing to their reactivity and function.
• Methoxyflurane: The presence of methoxy group affects its volatility and anesthetic properties.

Octet Rule

The octet rule is a fundamental principle in chemistry that guides the formation of stable molecules by ensuring atoms achieve an electron configuration similar to noble gases. This typically involves eight electrons in their outer shell. Applying this rule when drawing Lewis structures for inhaled anesthetics ensures that each atom through covalent bonds gains a full set of eight valence electrons, either through sharing or lone pairs.

In the context of inhaled anesthetics:

• Carbon generally forms four bonds to complete its octet.
• Halogens like fluorine, chlorine, and bromine form single bonds to satisfy their needs.
• Oxygen forms two bonds along with being able to possess lone pairs.

This rule provides a framework to predict molecular arrangement and reactivity, which is crucial for understanding how anesthetics function at a molecular level.

Carbon Central Atom

Carbon is frequently the central atom in organic molecules, and this holds true for many inhaled anesthetics. The presence of a carbon atom as a central point allows for the diverse structural possibilities due to its ability to form four covalent bonds, facilitating the construction of complex molecules.

In drawing the Lewis structures for inhaled anesthetics:

• Carbon's central role ensures that surrounding atoms, like fluorine, chlorine, or bromine, are adequately bonded and fulfill their valency.
• This versatility is seen in molecules like Halothane where carbon bonds with mixed halogens and hydrogen, forming stable structures.

Carbon's centrality not only dictates the shape and robustness of these molecules but also influences their anesthetic properties, by allowing specific molecular geometry that interacts optimally with the body's systems.

Lone Pairs

Lone pairs refer to the valence electrons that are not shared with another atom and remain as a pair on the atom. These play a crucial role in determining the shape and reactivity of molecules.

In inhaled anesthetics:

• Lone pairs are often found on electronegative atoms like oxygen, nitrogen, or halogens.
• These unbonded pairs can influence molecular geometry, which is essential for the proper functioning of the anesthetic.
• In Lewis structures, lone pairs are represented as pairs of dots, contributing to the octet rule compliance for each atom, particularly in compounds like Isoflurane or Methoxyflurane.

Understanding lone pairs allows chemists to predict molecular properties and interactions, gently tuning anesthetic efficacy and safety. By considering these pairs in the design and synthesis of anesthetics, scientists can refine their properties to meet specific medical needs.