Question

Ethyl bromide can be convert into ethyl alcohol by: (a) Heating with aqueous \(\mathrm{KOH}\). (b) Heating with alc \(\mathrm{KOH}\) (c) Heating with dry silver oxide (d) Heating with moist silver oxide.

Short answer

The correct methods are heating with aqueous KOH (a) and moist silver oxide (d).

Step-by-step solution

Identify Reactants and Products

Ethyl bromide ( C_2H_5Br ) can be converted to ethyl alcohol ( C_2H_5OH ). To achieve this transformation, a hydroxyl group (-OH) must replace the bromine atom in the molecule.

Explore Options

The exercise provides four options, each representing a different method. We need to find the correct method that would result in the substitution of bromine by a hydroxyl group.

Analyze Option (a) - Aqueous KOH

Heating ethyl bromide with aqueous KOH facilitates a nucleophilic substitution reaction where the bromine is replaced by the OH group from the KOH, forming ethyl alcohol.

Evaluate Option (b) - Alc KOH

Heating ethyl bromide with alcoholic KOH typically leads to an elimination reaction (dehydrohalogenation), not substitution, resulting in the formation of an alkene instead of alcohol.

Examine Option (c) - Dry Silver Oxide

Dry silver oxide does not provide the conditions necessary for a nucleophilic substitution of the bromine atom with a hydroxyl group.

Consider Option (d) - Moist Silver Oxide

Heating with moist silver oxide provides a sufficient source of hydroxide ions to substitute the bromine atom, converting the ethyl bromide to ethyl alcohol.

Conclusion

Upon reviewing the options, options (a) and (d) provide conditions that enable the conversion of ethyl bromide into ethyl alcohol through nucleophilic substitution.

Key concepts

Nucleophilic Substitution

In organic chemistry, nucleophilic substitution plays a vital role in converting one chemical group to another within a molecule. Let's break it down: a nucleophilic substitution reaction occurs when a nucleophile, which is a chemical species that donates an electron pair, displaces a leaving group in a molecule. This reaction generally takes place in two main ways, known as S_N1 and S_N2 mechanisms. Both lead to the replacement of an atom or a group in a molecule by a nucleophile, provided the conditions are suitable.

In the context of our exercise, ethyl bromide is the compound where the bromine atom needs to be replaced. The nucleophilic agent we utilize is the hydroxide ion ( ext{OH}^-), which becomes the attacking nucleophile, displacing the bromine and forming a new covalent bond to produce ethyl alcohol.

Ethyl Bromide

Ethyl bromide, known chemically as ext{C}_2 ext{H}_5 ext{Br}, is an organic compound that falls under the category of alkyl halides. It's characterized by its kind reactivity, mainly due to the presence of the polar C-Br bond which makes it a suitable candidate for nucleophilic substitution reactions. The bromine acts as a leaving group when a stronger nucleophile, such as ext{OH}^-, comes into play. This feature is what makes ethyl bromide an excellent starting material for preparing alcohols, as the bromine atom can be efficiently replaced by what you desire in your synthesis, in this case, a hydroxyl group.

Hydroxyl Group Replacement

The replacement of a bromine atom with a hydroxyl group involves intricacies that one would appreciate in the backdrop of a nucleophilic substitution. The hydroxyl group, ext{OH}, is introduced into the molecule where once laid the bromine atom. This transformation from ethyl bromide to ethyl alcohol is resourcefully achieved by either using aqueous KOH or moist silver oxide. The process is driven by the affinity of the hydroxyl ion to form a stable bond with the carbon atom, while the bromine leaves the scene as a neutral bromide ion. Such a transformation underpins many pathways for producing alcohols in organic chemistry labs and industrial scales.

Aqueous KOH

Aqueous KOH serves as a strong base as well as a source of nucleophiles. By dissolving potassium hydroxide in water, we produce ext{OH}^- ions, which are ready to engage in nucleophilic substitution with ethyl bromide. In the context of our reaction, aqueous KOH supplies the necessary hydroxide ions to invade and replace the bromine atom in the ethyl bromide structure. Through heating, we provide the activation energy required for the reaction to proceed efficiently towards the formation of ethyl alcohol. This reaction delineates how strategic use of solvents and conditions can tailor the outcome of chemical transformations.

Chemical Reactions

Chemical reactions are the heartbeats of chemistry, where substances are transformed into new entities through rearrangement of atoms and bonds. In the case of ethyl bromide conversion, the primary reaction is a substitution reaction, but it's important to consider other competing processes such as elimination, which may occur under slightly different conditions, like with alcoholic KOH. Understanding the nature and type of reaction provides clarity in predicting the products formed in given reactions.

• Nucleophilic substitution reactions typically involve the exchange of a leaving group for a nucleophile.
• Aqueous conditions can significantly favor substitution over elimination.
• Heat is often required to supply the necessary energy for bond breaking and formation.

Therefore, knowing the specific details of the reaction environment helps in predicting the correct pathway and outcome of an organic reaction.