The mass spectra of 1-methoxybutane, 2-methoxybutane, and 2-methoxy-2-methylpropane are shown below. Match each compound with its spectrum.
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Verified step by step guidance

1. Analyze the molecular structure of each compound (1-methoxybutane, 2-methoxybutane, and 2-methoxy-2-methylpropane) to identify key features that could influence fragmentation patterns in mass spectrometry. For example, consider the position of the methoxy group (-OCH₃) and the branching of the carbon chain.
2. Understand the general principles of mass spectrometry: molecules are ionized, and the resulting ions fragment in predictable ways. Look for characteristic peaks in the spectra, such as the molecular ion peak (M⁺), base peak (most intense peak), and other significant fragment peaks.
3. For 1-methoxybutane, predict the fragmentation pattern. The methoxy group is attached to the first carbon, so cleavage near this group may produce a fragment with a mass corresponding to CH₃O⁺ (31 m/z) and another fragment corresponding to the remaining alkyl chain.
4. For 2-methoxybutane, the methoxy group is attached to the second carbon. This structure may lead to fragmentation that produces a peak for CH₃O⁺ (31 m/z) and other fragments resulting from cleavage at the adjacent carbons, such as a peak for a secondary carbocation.
5. For 2-methoxy-2-methylpropane, the highly branched structure and the methoxy group on a tertiary carbon will influence fragmentation. Expect a strong molecular ion peak (M⁺) and significant peaks for tertiary carbocations or other stable fragments. Match these predicted patterns to the spectra to identify each compound.

Key Concepts

Mass Spectrometry

Mass spectrometry is an analytical technique used to measure the mass-to-charge ratio of ions. It involves ionizing chemical species and sorting the ions based on their mass. The resulting mass spectrum provides information about the molecular weight and structure of the compounds, allowing for the identification of different substances based on their fragmentation patterns.

Isomerism

Isomerism refers to the phenomenon where compounds have the same molecular formula but different structural arrangements or spatial orientations. In the case of 1-methoxybutane, 2-methoxybutane, and 2-methoxy-2-methylpropane, understanding their structural differences is crucial for interpreting their mass spectra, as these variations can lead to distinct fragmentation patterns.

Fragmentation Patterns

Fragmentation patterns are the specific ways in which a molecule breaks apart into smaller ions during mass spectrometry. Each compound has a unique fragmentation pattern based on its structure, which can be analyzed to deduce the original molecule. Recognizing these patterns is essential for matching the compounds to their respective mass spectra in the given question.