Question

Write equations for the reaction of 1 -butanol with each reagent. Where you predict no reaction, write NR. (a) Na metal (b) \(\mathrm{HBr}\), heat (c) \(\mathrm{HI}\), heat (d) \(\mathrm{PBr}_{3}\) (e) \(\mathrm{SOCl}_{2^{\prime}}\) pyridine (f) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7^{\prime}} \mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{H}_{2} \mathrm{O}\), heat (g) \(\mathrm{HIO}_{4}\) (h) \(\mathrm{PCC}\) (i) \(\mathrm{CH}_{3} \mathrm{SO}_{2} \mathrm{Cl}^{2}\), pyridine

Short answer

Also, identify any non-reacting combinations. Answer: The products are as follows: (a) sodium butoxide and hydrogen gas, (b) 1-bromobutane and water, (c) 1-iodobutane and water, (d) 1-bromobutane, HBr, and PBr2, (e) 1-chlorobutane, SO2, and HCl, (f) butanoic acid and water, (g) no reaction, and (h) butanal and PCC-H. Reagent combinations with no reaction are 1-butanol with HIO4 and CH3SO2Cl2 and pyridine.

Step-by-step solution

Sodium metal reaction with 1-butanol

When 1-butanol reacts with sodium metal, it forms sodium butoxide and releases hydrogen gas: $$ C_{4}H_{9}OH + Na \rightarrow C_{4}H_{9}ONa + \dfrac{1}{2} H_{2} $$ (b)

Reaction with HBr (heat)

Upon heating with HBr, 1-butanol undergoes nucleophilic substitution to form 1-bromobutane: $$ C_{4}H_{9}OH + HBr \xrightarrow{\text{heat}} C_{4}H_{9}Br + H_{2}O $$ (c)

Reaction with HI (heat)

1-butanol reacts with HI upon heating to form 1-iodobutane by nucleophilic substitution: $$ C_{4}H_{9}OH + HI \xrightarrow{\text{heat}} C_{4}H_{9}I + H_{2}O $$ (d)

Reaction with PBr3

1-butanol reacts with PBr3 to form 1-bromobutane via nucleophilic substitution: $$ C_{4}H_{9}OH + PBr_{3} \rightarrow C_{4}H_{9}Br + HBr + \dfrac{1}{3} PBr_{2} $$ (e)

Reaction with SOCl2 and pyridine

1-butanol reacts with SOCl2 in the presence of pyridine to form 1-chlorobutane via nucleophilic substitution: $$ C_{4}H_{9}OH + SOCl_{2} \xrightarrow[\text{pyridine}]{} C_{4}H_{9}Cl + SO_{2} + HCl $$ (f)

Reaction with K2Cr2O7, H2SO4, H2O (heat)

Upon heating with K2Cr2O7, H2SO4, and H2O, 1-butanol is oxidized to form butanoic acid: $$ C_{4}H_{9}OH \xrightarrow[\text{K2Cr2O7, H2SO4, H2O}]{\text{heat}} C_{4}H_{8}O_{2} + 4H_{2}O $$ (g)

Reaction with HIO4

1-butanol does not have a vicinal diol, so it will not react with HIO4: NR (h)

Reaction with PCC

1-butanol reacts with PCC to form butanal, undergoing controlled oxidation: $$ C_{4}H_{9}OH + PCC \rightarrow C_{4}H_{8}O + PCC-H $$ (i)

Reaction with CH3SO2Cl2 and pyridine

1-butanol does not react with CH3SO2Cl2 in the presence of pyridine: NR

Key concepts

Nucleophilic Substitution

Understanding the nucleophilic substitution reactions of 1-butanol is crucial for any student journeying through organic chemistry. A nucleophilic substitution reaction involves the replacement of a leaving group by a nucleophile. In simpler terms, a 'player' on the molecular team is swapped out for another. For instance, in the case of 1-butanol - a simple alcohol with the formula \( C_{4}H_{9}OH \), we see several examples of such substitutions.

In the reactions with \( \mathrm{HBr} \), \( \mathrm{HI} \), \( \mathrm{PBr}_{3} \), and \( \mathrm{SOCl}_{2} \), 1-butanol interacts with these reagents, each time replacing the hydroxyl group \( -OH \) with halides like \( -Br \) or \( -Cl \) through the attack of a nucleophile. What facilitates this exchange is a favorable leaving condition for the hydroxyl group, usually transformed into a better leaving group in the reaction environment, often with the assistance of a catalyst or heat.

Why Does This Matter?

Understanding the preference of 1-butanol to engage in such changes and the conditions needed, can help predict reactivity and outcomes in a variety of chemical syntheses and is fundamental to designing new molecules in labs.

Oxidation Reactions

Now, let's dive into the world of 1-butanol undergoing oxidation reactions. Oxidation, in the realm of organic chemistry, often refers to the process where a carbon atom forms more bonds to oxygen (or loses hydrogen). 1-butanol presents textbook examples of oxidation when it interacts with specific agents.

For example, with \( \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \), \( \mathrm{H}_{2}\mathrm{SO}_{4} \), and heat, 1-butanol is transformed into butanoic acid. This is a classic oxidation that converts the -OH group into a carboxylic acid functional group. Another oxidation reaction is seen with pyridinium chlorochromate (\(\mathrm{PCC}\)). It oxidizes 1-butanol, but more subtly, to an aldehyde (butanal), not proceeding to the acid stage.

Real-World Application

Understanding such transformations is not just academic; these reactions are the backbone of creating a myriad of compounds within industries, from pharmaceuticals to materials science.

Organic Chemistry Reagents

When exploring reactions of organic compounds like 1-butanol, students must acquaint themselves with the diverse cast of reagents that drive chemical transformations. These reagents are substances or compounds that are added to a system to bring about a chemical reaction or are present during the reaction.

For 1-butanol, we encounter a variety of reagents such as \( \mathrm{HBr} \), \( \mathrm{HI} \), \( \mathrm{PBr}_{3} \) and \( \mathrm{SOCl}_{2} \) which push for nucleophilic substitution, to strong oxidizers like \( \mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7} \) in sulfuric acid and pyridinium chlorochromate (\( \mathrm{PCC} \) which lead to varying degrees of oxidation. However, not all reagents interact. For instance, \( \mathrm{HIO}_{4} \) and \( \mathrm{CH}_{3} \mathrm{SO}_{2} \mathrm{Cl} \) do not react with 1-butanol under the given conditions.

A Tool for Analysis

Being familiar with these reagents and their roles can help students predict reaction outcomes, which is an essential skill in organic synthesis and analytical chemistry.