FlavScents AInsights Entry for 2-methyl-1-butanol (CAS: 137-32-6)

1. Identity & Chemical Information

2-methyl-1-butanol, also known as active amyl alcohol, is a single chemical compound with the IUPAC name 2-methylbutan-1-ol. It is identified by the CAS number 137-32-6. The FEMA number for this compound is 2047. Other identifiers include the FL number 02.015 and CoE number 246. The molecular formula of 2-methyl-1-butanol is C5H12O, and it has a molecular weight of 88.15 g/mol. This compound contains a primary alcohol functional group, which contributes to its characteristic odor profile. The structure-odor relevance is significant as the branching in the carbon chain influences its sensory attributes, providing a fusel oil-like aroma.

Citation hooks: FlavScents; PubChem; FEMA

2. Sensory Profile

2-methyl-1-butanol is characterized by a strong, fusel oil-like odor with a slightly sweet, alcoholic note. It is often described as having a pungent, solvent-like aroma with a hint of fruitiness. The intensity of its odor is moderate to strong, and it is known for its ability to diffuse well in formulations. The taste threshold of 2-methyl-1-butanol is not clearly reported, but it is typically used as a background realism note in flavor compositions, providing depth and complexity.

Citation hooks: FlavScents; peer-reviewed sensory literature

3. Natural Occurrence & Formation

2-methyl-1-butanol naturally occurs in various fruits and alcoholic beverages. It is a byproduct of fermentation processes, particularly in the production of beer and wine, where it contributes to the fusel oil fraction. The compound can also be formed through the enzymatic degradation of amino acids such as leucine. Its presence in natural sources allows it to be designated as a "natural flavor" in certain regulatory contexts.

Citation hooks: FlavScents; food chemistry literature; EFSA/JECFA monographs

4. Use in Flavors

In flavor applications, 2-methyl-1-butanol is used across various categories, including alcoholic beverages, fruit flavors, and confectionery. It serves as a functional component that enhances the authenticity and complexity of flavor profiles. Typical use levels in finished food or beverage products range from 1 to 50 ppm, with low levels providing subtle background notes and higher concentrations offering more pronounced effects. The compound is relatively stable under typical processing conditions but may be susceptible to oxidation.

Citation hooks: FlavScents; FEMA GRAS documentation; formulation literature

5. Use in Fragrances

2-methyl-1-butanol is utilized in fragrance formulations, particularly within the fougère and chypre families. It acts as a modifier and impact note, contributing to the overall realism and depth of the fragrance. Typical concentration ranges in fragrance products are from trace amounts to 0.5%, depending on the desired effect. The compound is volatile, contributing primarily to the top and middle notes of a fragrance composition.

Citation hooks: FlavScents; IFRA; fragrance chemistry texts

6. Regulatory Status (Regional Overview)

In the United States, 2-methyl-1-butanol is recognized as GRAS (Generally Recognized As Safe) by FEMA for flavor use. In the European Union, it is regulated under Regulation (EC) No 1334/2008 and has an assigned FL number. The United Kingdom follows similar regulations post-Brexit. In Asia, including Japan and China, it is generally accepted for use in flavors, though specific regulations may vary. In Latin America, countries like Brazil and those in MERCOSUR have harmonized regulations that typically align with international standards.

Citation hooks: FEMA; EFSA; national authority publications

7. Toxicology, Safety & Exposure Considerations

For oral exposure, 2-methyl-1-butanol has a low acute toxicity profile, with an acceptable daily intake (ADI) not clearly established but considered safe at typical use levels. Dermal exposure in fragrance applications is generally safe, with low potential for irritation or sensitization, as per IFRA guidelines. Inhalation exposure is primarily relevant in occupational settings, where adequate ventilation is recommended to minimize risks. The risk profiles for food and fragrance applications are similar, with no significant differences noted.

Citation hooks: EFSA; FEMA; PubChem; toxicology literature

8. Practical Insights for Formulators

2-methyl-1-butanol is valued for its ability to enhance the authenticity and complexity of both flavor and fragrance formulations. It synergizes well with other alcohols and esters, providing a balanced and nuanced profile. Common formulation pitfalls include overuse, which can lead to an overpowering solvent-like note. It is frequently under-used in applications where subtlety and depth are desired.

Citation hooks: FlavScents; industry practice

9. Confidence & Data Quality Notes

The data on 2-methyl-1-butanol is well-established, with comprehensive sensory and regulatory information available. Industry practices are well-documented, though some specific numeric values, such as taste thresholds, are not clearly reported. Regulatory ambiguities are minimal, with harmonized standards across major regions.

Citation hooks: FlavScents

QA Check

• All required sections 1–9 are present
• "Citation hooks:" line is present under each section
• Flavor section includes ppm ranges
• Toxicology section covers oral, dermal, inhalation
• Regulatory section mentions US, EU, UK, Asia, Latin America
• If complex natural material: includes section 5a (not applicable here)

About FlavScents AInsights (Disclosure)
FlavScents AInsights integrates information from authoritative government, scientific, academic, and industry sources to provide applied, exposure-aware insight into flavor and fragrance materials. Data are drawn from regulatory bodies, expert safety panels, peer-reviewed literature, public chemical databases, and long-standing professional practice within the flavor and fragrance community. Where explicit published values exist, they are reported directly; where gaps remain, AInsights reflects widely accepted industry-typical practice derived from convergent sensory behavior, historical commercial use, regulatory non-objection, and expert consensus. All such information is clearly labeled to distinguish documented data from professional guidance or informed estimation, with the goal of offering transparent, practical, and scientifically responsible context for researchers, formulators, and regulatory specialists. This section is generated using advanced computational language modeling to synthesize and structure information from established scientific and regulatory knowledge bases, with the intent of supporting—not replacing—expert review and judgment.

Generated 2026-03-04 15:06:44 GMT (p2)