Give the structure of each of the following aromatic hydrocarbons. a. \(o\) -ethyltoluene b. \(p\) -di-tert-butylbenzene c. \(m\) -diethylbenzene d. 1-phenyl-2-butene

The aromatic hydrocarbon known as ortho-ethyltoluene reflects a very specific molecular configuration. This compound is a derivative of toluene, which is a benzene ring with a single methyl group attached.

In ortho-ethyltoluene, 'ortho' refers to the placement of a second substituent, in this case, an ethyl group (-CH₂CH₃), adjacent to the methyl group on the benzene ring. To envision this, imagine a hexagonal benzene ring with one side adorned with a methyl group. Directly next to it, on either of the two adjoining carbons, you place the ethyl group. The defining feature of the ortho position is this close proximity, which induces distinctive chemical properties and reactivity patterns due to the interaction between the substituents.

• Draw a hexagonal benzene ring with alternating single and double bonds.
• Add a methyl group to one of the carbons.
• Adjacent to the methyl group, add an ethyl group to the next carbon in either direction.

Understanding this structure is crucial when predicting the behavior of the compound in chemical reactions.

Para-di-tert-butylbenzene is another interesting aromatic molecule, showcasing how multiple, bulky substituents affect a benzene's structure. The 'para' configuration means that two substituents are located opposite each other on the benzene ring, at the 1 and 4 positions.

In this compound, the substituents are tert-butyl groups (-C(CH₃)₃), which consist of a central carbon atom attached to three methyl groups. This bulky nature can influence the molecule's physical properties, such as its melting point and solubility. To construct the structure, follow these steps:

• Sketch a benzene ring, marking positions 1 and 4.
• Add one tert-butyl group at position 1 and another at position 4 of the ring.

Recognizing the para position is essential for understanding how such groups can sterically hinder or influence reactions due to their placement on the benzene ring.

Meta-diethylbenzene, a compound with two ethyl groups attached to a benzene ring, presents yet another aromatic structure to comprehend. In this case, 'meta' indicates that the substituents are separated by one carbon atom on the ring, typically found at the 1 and 3 positions.

When drawing meta-diethylbenzene, position the two ethyl groups such that one carbon of the benzene ring sits between them. This arrangement has implications for the compound’s chemistry, often yielding different reactivity compared to ortho or para configurations. To draw this structure:

• Begin with a benzene ring and locate positions 1 and 3.
• Attach an ethyl group at each of these positions.

Understanding the meta placement aids in predicting electronic effects and the resulting chemical behavior.

The molecule 1-phenyl-2-butene combines aspects of both aliphatic and aromatic chemistry. It’s constructed by grafting a benzene ring onto an alkene carbon chain.

Specifically, '1-phenyl' tells us the benzene ring is attached to the first carbon of 2-butene, a four-carbon-chain alkene with a double bond between the second and third carbons. This introduces interesting aspects of geometry and bonding, as the planar aromatic ring is connected to a potentially nonplanar alkene depending on the geometry around the double bond. To illustrate this molecule, one would:

• Sketch out a linear 2-butene, marking the carbon atoms from 1 to 4.
• At the first carbon, append a phenyl group (a benzene ring).

This structure plays a role in UV-Vis spectrometry, material science, and potential reactivity scenarios encountered in organic synthesis.