Question

What is the product formed when bromoethane reacts with excess of sodium hydrogen sulfide?

Short answer

The product formed is ethyl mercaptan (ethanethiol).

Step-by-step solution

Identify the Reactants

In this reaction, the reactants are bromoethane, which is an alkyl halide, and sodium hydrogen sulfide, a compound known for its nucleophilic properties.

Understand the Reaction Type

The reaction between an alkyl halide and a compound like sodium hydrogen sulfide typically undergoes a substitution reaction where the halide (bromine) is replaced by a nucleophile (sulfide ion).

Write the Reaction Equation

The reaction can be represented as \[\text{C}_2\text{H}_5\text{Br} + \text{NaHS} \rightarrow \text{C}_2\text{H}_5\text{SH} + \text{NaBr}\]Here, bromoethane reacts with sodium hydrogen sulfide to form ethyl mercaptan (also known as ethanethiol) and sodium bromide.

Identify the Product Formed

The primary product formed in this reaction is ethyl mercaptan (ethanethiol), which is identified by the chemical formula \(\text{C}_2\text{H}_5\text{SH}\).

Key concepts

Alkyl Halide

Alkyl halides, such as bromoethane, are organic compounds that contain a halogen atom bonded to an alkyl group. The alkyl group is essentially a carbon chain that is bound to a halogen like bromine, chlorine, or iodine. In the case of bromoethane, the molecule consists of a two-carbon chain (ethyl group) attached to a bromine atom.

These compounds are reactive, particularly because the carbon-halogen bond is polar. The halogen atom is more electronegative than carbon, creating an uneven distribution of charge. This polarization makes alkyl halides excellent substrates for various chemical reactions, especially substitution reactions.

• Used as intermediates in chemical synthesis
• Common in reactions in organic chemistry

Understanding how these compounds interact with other substances can help in predicting the outcome of reactions and the types of products formed.

Nucleophile

A nucleophile is a chemical species that has the ability to donate a pair of electrons to form a chemical bond with an electrophile. Nucleophiles are often negatively charged or have electron-rich areas that make them attractive to positively charged centers.

In our reaction, sodium hydrogen sulfide acts as the nucleophile. The sulfide ion is rich in electrons and seeks out positively charged regions or centers, such as the carbon atom bonded to the halogen in an alkyl halide.

• Electron-rich and negatively charged
• Key players in substitution reactions
• Form bonds by donating electron pairs

Through this process, nucleophiles replace the leaving group, which is the halogen atom in the alkyl halide, leading to the formation of new compounds.

Reaction Equation

The reaction equation provides a concise way to convey the chemical change occurring during a reaction. In this exercise, bromoethane (an alkyl halide) reacts with sodium hydrogen sulfide to form ethyl mercaptan and sodium bromide.

The chemical equation is written as:
\[ \text{C}_2\text{H}_5\text{Br} + \text{NaHS} \rightarrow \text{C}_2\text{H}_5\text{SH} + \text{NaBr} \]

This equation captures the essence of the substitution reaction. The sulfide ion from sodium hydrogen sulfide replaces the bromine in bromoethane, resulting in the formation of ethyl mercaptan and sodium bromide.

• Shows reactants and products
• Highlights type of chemical reaction
• Key tool for predicting reaction outcome

The balanced equation is crucial for understanding the stoichiometry and ensuring that the conservation of mass is maintained in chemical reactions.

Ethyl Mercaptan

Ethyl mercaptan, also known as ethanethiol, is a sulfur-containing organic compound with the formula \(\text{C}_2\text{H}_5\text{SH}\). It is the main product formed in the given substitution reaction. This compound is characterized by the presence of a characteristic sulfhydryl or thiol group (-SH), which imparts a distinct smell reminiscent of rotten eggs or skunk spray.

Ethyl mercaptan is commonly used in the industry due to its odorant properties, particularly to add smell to otherwise odorless gases. Also noteworthy is its ability to readily form chemical bonds due to its reactive thiol group.

• Contains a sulfhydryl group making it reactive
• Commonly used as an odorant in natural gas
• Important in chemical manufacturing

Understanding its structure and properties is important not only for carrying out specific chemical reactions but also for practical applications in odor detection systems.