--- title: "Butyraldehyde | Organic Chemistry" description: "Butyraldehyde is the aldehyde CH3CH2CH2CHO, also called butanal, and it shows how terminal carbonyls are named, oxidized, and used in Organic Chemistry." canonical: "https://fiveable.me/organic-chem/key-terms/butyraldehyde" type: "key-term" subject: "Organic Chemistry" unit: "Unit 19" --- # Butyraldehyde | Organic Chemistry ## Definition Butyraldehyde is a four-carbon aldehyde with the formula CH3CH2CH2CHO, also called butanal. In Organic Chemistry, it is a simple terminal carbonyl compound used to practice naming and oxidation patterns. ## What It Is Butyraldehyde is the common name for butanal, a four-carbon aldehyde with the structure CH3CH2CH2CHO. In Organic Chemistry, it is one of the simplest examples of a terminal carbonyl compound, so it shows up when you are naming aldehydes, drawing structures from names, and predicting reactions. The molecule ends with the aldehyde group, which means the carbonyl carbon is at the end of the chain and bonded to at least one hydrogen. That terminal placement is what makes it an aldehyde instead of a ketone. If you see the name butyraldehyde or butanal, you should picture a straight four-carbon chain with the carbonyl on carbon 1. The naming tells you a lot. The root but- means four carbons, and the suffix -al tells you aldehyde. The older common name, butyraldehyde, is still seen in some contexts, especially when compounds are being discussed by common names rather than strict IUPAC names. In a class problem, you may be asked to recognize that butyraldehyde and butanal refer to the same structure. Chemically, the carbonyl carbon is partially positive because oxygen pulls electron density toward itself. That makes aldehydes good targets for nucleophiles. Butyraldehyde can undergo the same broad reactions as many aldehydes, including nucleophilic addition, and it can be oxidized to butyric acid. That oxidation is a classic aldehyde behavior, because aldehydes are easier to oxidize than ketones. It also sits in the homologous series of aldehydes. Compared with formaldehyde, acetaldehyde, and propionaldehyde, butyraldehyde has one more carbon added to the chain. That pattern matters because members of the same series share the same functional group, but their physical properties change as the carbon chain gets longer. So when butyraldehyde comes up in Organic Chemistry, it is usually not as a stand-alone fact to memorize. It is a model molecule for seeing how aldehyde naming, carbonyl reactivity, and oxidation all fit together. ## Why It Matters Butyraldehyde matters because it is a clean example of the aldehyde patterns you keep using across Organic Chemistry. Once you can identify butyraldehyde as butanal, you can move faster on naming questions, structure-drawing problems, and reaction prediction. It also reinforces the idea that the carbonyl group controls reactivity. The partially positive carbonyl carbon is the site a nucleophile attacks, so butyraldehyde gives you a straightforward way to think about aldehyde reactions without extra structural clutter. That makes it a useful reference point when you compare aldehydes to ketones or when you decide whether oxidation is likely. The oxidation to butyric acid is another reason it shows up. If a problem asks what happens when an aldehyde is oxidized, butyraldehyde gives you a direct example: the aldehyde group becomes a carboxylic acid. That before-and-after change is one of the most common transformations in carbonyl chemistry. It also helps with vocabulary. A lot of organic chemistry feels like naming, but the names are tied to structure and behavior. Seeing butyraldehyde as part of the homologous series helps you connect the prefix, the suffix, and the functional group instead of treating the term like a random label. ## Connections ### [Butanal](/organic-chem/key-terms/butanal) Butanal is the IUPAC name for butyraldehyde, so the two names point to the same molecule. In naming problems, you may see one version in a prompt and need to recognize the other as the systematic form. That switch between common and IUPAC naming is a frequent skill in aldehyde questions. ### Aldehyde Butyraldehyde is an aldehyde, which means it has a terminal carbonyl group. That classification tells you where the carbonyl sits on the chain and what reactions it usually undergoes. If you can identify the aldehyde functional group, you can usually predict naming, oxidation, and addition behavior more accurately. ### [Carbonyl Group](/organic-chem/key-terms/carbonyl-group) The carbonyl group is the reactive center in butyraldehyde. Oxygen pulls electron density away from the carbon, making that carbon partially positive and vulnerable to nucleophilic attack. This is the same core electronic idea behind many aldehyde and ketone reactions, so it is worth connecting the term back to the carbonyl itself. ### [Homologous Series](/organic-chem/key-terms/homologous-series) Butyraldehyde belongs to the homologous series of aldehydes, along with smaller molecules like formaldehyde and acetaldehyde. The shared functional group keeps their chemistry related, while the extra carbons change size, boiling point, and other physical properties. That pattern is a big reason homologous series show up so often in organic naming and comparison questions. ## On the AP Exam A naming question may show you a four-carbon chain with an end carbonyl and ask for the compound name, or it may give you the name butyraldehyde and ask you to draw the structure. You should recognize that the aldehyde carbon is carbon 1 and that the IUPAC name is butanal. If a reaction question involves oxidation, you should know that an aldehyde like butyraldehyde can become butyric acid. On problem sets and quizzes, you may also be asked to compare aldehydes and ketones by looking at the carbonyl position. That is where butyraldehyde works as a clean example, since its terminal carbonyl makes the aldehyde identity obvious. If you can identify the functional group quickly, the rest of the question usually gets much easier. ## Butyraldehyde vs Acetaldehyde Acetaldehyde and butyraldehyde are both aldehydes, but they do not have the same carbon count. Acetaldehyde has two carbons total, while butyraldehyde has four. The shared ending can make them easy to mix up, so checking the chain length is the fastest way to tell them apart. ## Key Takeaways - Butyraldehyde is the common name for butanal, a four-carbon aldehyde with the formula CH3CH2CH2CHO. - The aldehyde carbonyl is terminal, so the carbonyl carbon is carbon 1 in the chain. - Because it is an aldehyde, butyraldehyde can be oxidized to butyric acid. - The carbonyl carbon is partially positive, which is why nucleophiles attack aldehydes readily. - Butyraldehyde is useful in Organic Chemistry as a naming and reactivity example, not just as a memorized molecule. ## FAQs ### What is butyraldehyde in Organic Chemistry? Butyraldehyde is a four-carbon aldehyde with the formula CH3CH2CH2CHO. Its IUPAC name is butanal, and the aldehyde group sits at the end of the carbon chain. In organic chemistry, it is a simple example used to practice aldehyde naming and reactions. ### Is butyraldehyde the same as butanal? Yes. Butyraldehyde is the common name, and butanal is the IUPAC name. Both names describe the same molecule, so a question using either term is asking about the same structure. ### How do you recognize butyraldehyde on a structure? Look for a four-carbon chain with a terminal carbonyl group, meaning the C=O is on the end of the molecule and attached to a hydrogen. That end placement tells you it is an aldehyde, not a ketone. If the chain has four carbons total, the compound is butyraldehyde or butanal. ### What happens when butyraldehyde is oxidized? Like other aldehydes, butyraldehyde can be oxidized to a carboxylic acid, specifically butyric acid. This is a common aldehyde reaction pattern. If a problem asks you to predict the oxidation product, keep the carbon chain the same and change the aldehyde group into a carboxylic acid. ## Related Study Guides - [19.1 Naming Aldehydes and Ketones](/organic-chem/unit-19/naming-aldehydes-ketones/study-guide/vrqMqYawrKYR357W) ## About This Document Canonical Fiveable pages are available as Markdown at the same path plus `.md`. - [llms.txt](https://fiveable.me/llms.txt): index of Fiveable's sections and URL patterns - [llms-full.txt](https://fiveable.me/llms-full.txt): complete subject and unit listing - [MCP server](https://fiveable.me/mcp): call Fiveable as tools instead of fetching pages (`https://fiveable.me/api/mcp`) - [MCP server for AP teachers](https://fiveable.me/mcp/teachers): a teacher's classes, assignments and AP-rubric grading (`https://fiveable.me/api/mcp/teacher`) ## Structured Data ```json {"@context":"https://schema.org","@graph":[{"@type":"LearningResource","@id":"https://fiveable.me/organic-chem/key-terms/butyraldehyde#resource","name":"Butyraldehyde | Organic Chemistry","url":"https://fiveable.me/organic-chem/key-terms/butyraldehyde","learningResourceType":"Concept explainer","educationalLevel":"AP® / High School","about":{"@id":"https://fiveable.me/organic-chem/key-terms/butyraldehyde#term"},"audience":{"@type":"EducationalAudience","educationalRole":"student"},"dateModified":"2026-07-03T02:23:39.422Z","isPartOf":{"@type":"Collection","name":"Organic Chemistry Key Terms","url":"https://fiveable.me/organic-chem/key-terms"},"publisher":{"@type":"Organization","name":"Fiveable","url":"https://fiveable.me"}},{"@type":"DefinedTerm","@id":"https://fiveable.me/organic-chem/key-terms/butyraldehyde#term","name":"Butyraldehyde","description":"Butyraldehyde is a four-carbon aldehyde with the formula CH3CH2CH2CHO, also called butanal. 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