1-Bromobutane
[CAS# 109-65-9]

Identification

• Classification: Organic raw materials >> Hydrocarbon compounds and their derivatives >> Hydrocarbon halide
• Name: 1-Bromobutane
• Synonyms: n-Butyl bromide
• Molecular Formula: C₄H₉Br
• Molecular Weight: 137.02
• CAS Registry Number: 109-65-9
• EC Number: 203-691-9
• SMILES: CCCCBr

Properties

• Density: 1.3±0.1 g/cm³ Calc.^*, 1.276 g/mL (Expl.)
• Melting point: -112 °C (Expl.)
• Boiling point: 101.6±3.0 °C 760 mmHg (Calc.)^*, 100 - 104 °C (Expl.)
• Flash point: 23.9 °C (Calc.)^*, 10 °C (Expl.)
• Solubility: water 0.608 g/L (30 °C) (Expl.)
• Index of refraction: 1.439 (Calc.)^*, 1.439 (Expl.)

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS02;GHS07;GHS08;GHS09 Danger
• Risk Statements: H225-H226-H315-H319-H335-H351-H360FD-H373-H411
• Safety Statements: P203-P210-P233-P240-P241-P242-P243-P260-P261-P264-P264+P265-P271-P273-P280-P302+P352-P303+P361+P353-P304+P340-P305+P351+P338-P318-P319-P321-P332+P317-P337+P317-P362+P364-P370+P378-P391-P403+P233-P403+P235-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Flammable liquids	Flam. Liq.	2	H225
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	1B	H360FD
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Flammable liquids	Flam. Liq.	3	H226
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Reproductive toxicity	Repr.	1B	H360
Germ cell mutagenicity	Muta.	2	H341
Acute hazardous to the aquatic environment	Aquatic Acute	2	H401
Eye irritation	Eye Irrit.	2A	H319

• Transport Information: UN 1126

Discovery and Applications

1-Bromobutane is an organic compound belonging to the family of alkyl halides, specifically a straight-chain primary bromoalkane with the molecular formula C₄H₉Br. It appears as a colorless to pale yellow liquid with a characteristic odor and has been known and studied for many decades as both a chemical reagent and an intermediate in organic synthesis. The compound is denser than water and only slightly soluble in it, while being miscible with most organic solvents. Because of its relatively simple structure, 1-bromobutane has long been employed as a model compound in the study of reaction mechanisms involving nucleophilic substitution and elimination.

The preparation of 1-bromobutane historically involved the reaction of 1-butanol with hydrobromic acid, a process that provided one of the earliest demonstrations of alcohol halogenation. This transformation has since become a textbook example of converting alcohols to alkyl halides and is commonly taught in organic chemistry courses as part of the substitution mechanism involving protonation of the hydroxyl group, followed by replacement with bromide. Industrially, 1-bromobutane can also be produced by the addition of hydrogen bromide to 1-butene, providing an efficient route to large-scale quantities.

From a synthetic standpoint, 1-bromobutane is most valued as an alkylating agent. The bromine atom serves as a good leaving group, enabling the compound to undergo nucleophilic substitution reactions readily with a wide range of nucleophiles. For example, treatment with cyanide yields pentanenitrile, while reaction with alkoxides produces ethers through Williamson ether synthesis. Similarly, interaction with ammonia or amines gives rise to primary, secondary, or tertiary butylamines, depending on the reaction conditions and molar ratios. Because of this reactivity, the compound is often used in the laboratory as a starting point for the preparation of more complex molecules.

Another important use of 1-bromobutane is as a building block in the synthesis of pharmaceuticals, agrochemicals, and specialty chemicals. For instance, the ability to introduce a butyl group into larger molecular frameworks through nucleophilic substitution makes it valuable for tailoring the solubility and bioavailability of drug candidates. In the field of surfactants and lubricants, butyl-containing intermediates derived from 1-bromobutane play a role in improving hydrophobic interactions and altering physical properties of end products. Similarly, it has been employed in the preparation of quaternary ammonium salts, which are used as disinfectants, phase transfer catalysts, and antistatic agents.

In addition to its synthetic versatility, 1-bromobutane has significance in mechanistic chemistry as a substrate for kinetic studies. Because it is a primary alkyl halide, it predominantly undergoes bimolecular nucleophilic substitution (S_N2) reactions, which makes it a common choice for examining the effect of nucleophile strength, solvent polarity, and steric hindrance on reaction rates. These experiments have been central to the understanding of substitution mechanisms, contrasting the behavior of primary, secondary, and tertiary halides. The predictable reactivity of 1-bromobutane makes it a standard example in laboratory instruction, especially in undergraduate organic chemistry laboratories.

Although the compound is widely used, handling requires attention to safety due to its irritant properties. Contact with the skin or eyes can cause irritation, and inhalation of vapors may lead to respiratory discomfort. Like many alkyl halides, 1-bromobutane also poses risks of central nervous system effects at higher exposures. Therefore, laboratory use necessitates appropriate precautions such as working in well-ventilated spaces, employing fume hoods, and wearing protective gloves and goggles. From an environmental perspective, the compound is moderately persistent and may present hazards to aquatic life, which underlines the need for responsible disposal practices in both academic and industrial contexts.

Over time, the role of 1-bromobutane has remained consistent in both education and industrial chemistry. It continues to serve as a fundamental example of halogenated hydrocarbon reactivity, as a convenient reagent for preparing a wide spectrum of organic derivatives, and as a tool for exploring fundamental principles of chemical kinetics and mechanisms. While it is not a large-volume industrial commodity compared to other halogenated hydrocarbons, its importance lies in its versatility as a synthetic intermediate and its enduring role in illustrating core chemical concepts.

References

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1991. Toxicity Study. Environmental Monitoring and Assessment, 19(1).
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2018. Ionic Liquid Synthesis. Analytical and Bioanalytical Chemistry, 410(3).
DOI: 10.1007/s00216-017-0820-x