Question

Draw structures for the following compounds: (a) 1,4-butanediol (b) 3 -amino-1-pentanol (c) cis-4-tert-butoxycyclohexanol (d) \(2,2,4,4\)-tetramethyl-3-pentanol (e) \((R)\)-sec-butyl alcohol (f) trans-3-chlorocyclohexanol (g) tert-butyl cyclopentyl ether

Short answer

1,4-Butanediol, 3-amino-1-pentanol, cis-4-tert-butoxycyclohexanol, 2,2,4,4-tetramethyl-3-pentanol, (R)-sec-butyl alcohol, trans-3-chlorocyclohexanol, tert-butyl cyclopentyl ether.

Step-by-step solution

- Identify the functional groups and main chain

For each compound, determine the functional groups and the main carbon chain. This helps in sketching the basic structure.

- Draw the basic skeleton

Sketch the carbon skeleton as identified in the previous step for each compound.

- Add functional groups

Attach the identified functional groups to the correct positions on the carbon skeleton.

- Check for stereochemistry if given

For compounds with stereochemical designations (cis, trans, R, S), ensure to depict the correct three-dimensional arrangement of substituents.

Key concepts

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In organic chemistry, identifying functional groups is essential as they dictate reactivity and properties.
For the given exercise compounds, here are the main functional groups:

• 1,4-butanediol: Two hydroxyl groups (-OH) at positions 1 and 4
• 3-amino-1-pentanol: One hydroxyl group (-OH) at position 1 and an amino group (-NH2) at position 3
• cis-4-tert-butoxycyclohexanol: One hydroxyl group (-OH) and one tert-butoxy group (-O-tert-Bu) at position 4 on a cyclohexane ring
• 2,2,4,4-tetramethyl-3-pentanol: One hydroxyl group (-OH) and four methyl groups (-CH3) at specific positions
• (R)-sec-butyl alcohol: One hydroxyl group (-OH) on a secondary butyl chain with R configuration
• trans-3-chlorocyclohexanol: One hydroxyl group (-OH) and one chlorine atom at position 3 on a cyclohexane ring
• tert-butyl cyclopentyl ether: An ether linkage (-O-) connecting a tert-butyl group and a cyclopentyl ring

Recognizing these functional groups helps in knowing how to build each molecule.

Carbon Skeleton

The carbon skeleton of a molecule forms the backbone structure upon which functional groups are attached. It determines the overall shape and framework of the molecule.
To correctly draw the carbon skeleton:

• Identify the primary carbon chain or ring system.
• Count the number of carbons to ensure accuracy.
• Consider any branching or cyclic structures needed.

For example, in 1,4-butanediol, the main chain is a straight four-carbon chain since 'butane' indicates four carbons. For cis-4-tert-butoxycyclohexanol, the skeleton is a six-carbon ring (cyclohexane). Identifying the main carbon structure is crucial before adding any functional groups.

Stereochemistry

Stereochemistry refers to the three-dimensional arrangement of atoms within molecules, impacting their physical and chemical properties. It is vital to represent stereochemistry correctly in drawings, especially for molecules with specific spatial arrangements.
Two common types of stereochemistry in this exercise are:

• cis/trans Isomerism: For compounds like cis-4-tert-butoxycyclohexanol and trans-3-chlorocyclohexanol, ensure substituents are on the same (cis) or opposite (trans) sides of the ring.
• R/S Configuration: For compounds like (R)-sec-butyl alcohol, use the Cahn-Ingold-Prelog priority rules to determine the correct arrangement of substituents around a chiral center. R (rectus) means the priorities decrease in a clockwise direction.

Correctly drawing these arrangements is crucial for accurate representation and understanding of the molecule's reactivity and interaction.

Organic Compounds

In organic chemistry, we study compounds primarily composed of carbon atoms bonded to hydrogen, oxygen, nitrogen, and other elements. The given exercise involves various organic compounds with distinct characteristics:

• Alcohols: Compounds (a), (b), (c), (d), and (e) have hydroxyl groups (-OH) as their primary functional group, making them alcohols. Each has unique substituents affecting their structure and reactivity.
• Amines: Compound (b) includes an amino group (-NH2) in addition to a hydroxyl group, creating an amino alcohol.
• Ethers: Compound (g) is an ether, featuring an oxygen atom connected to two different alkyl groups (tert-butyl and cyclopentyl).

Understanding the nature of these organic compounds allows you to predict their physical and chemical behavior based on their functional groups and molecular structure.