Identify each of the following compounds from the 1H NMR data and molecular formula: b. C8H9Br: a 3H doublet at 2.01 ppm a 1H quartet at 5.14 ppm a 5H broad singlet at 7.35 ppm

Verified step by step guidance

1. Examine the molecular formula C8H9Br and note that it suggests an aromatic compound due to the presence of 5 hydrogens in a broad singlet at 7.35 ppm, which is typical for aromatic protons.
2. Identify the 3H doublet at 2.01 ppm, which indicates a methyl group (CH3) adjacent to a CH group, likely part of an ethyl group.
3. Consider the 1H quartet at 5.14 ppm, which suggests a CH group that is adjacent to a CH3 group, confirming the presence of an ethyl group.
4. Combine the information: the aromatic ring accounts for C6H5, the ethyl group (CH2-CH3) accounts for C2H4, and the bromine atom completes the molecular formula C8H9Br.
5. Conclude that the compound is likely an ethylbenzene derivative with a bromine substituent, such as bromoethylbenzene.

Key Concepts

1H NMR Spectroscopy

Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. It provides information about the number of hydrogen atoms in different environments, their chemical shifts (ppm), and the splitting patterns, which indicate the number of neighboring hydrogen atoms. Understanding these signals helps in deducing the molecular structure and connectivity of the compound.

Chemical Shifts and Splitting Patterns

In 1H NMR, chemical shifts are measured in parts per million (ppm) and indicate the electronic environment of hydrogen atoms. For example, a doublet suggests that a hydrogen atom is adjacent to one other hydrogen, while a quartet indicates three neighboring hydrogens. The specific chemical shifts and splitting patterns provide clues about the functional groups and the overall structure of the compound being analyzed.

Molecular Formula Interpretation

The molecular formula provides essential information about the number and types of atoms in a compound. For C8H9Br, the formula indicates the presence of 8 carbon atoms, 9 hydrogen atoms, and 1 bromine atom. This information, combined with NMR data, allows chemists to deduce possible structures and identify the compound by matching the spectral data with known compounds.