$\text{CH}_3\text{Br} + \text{Nu}^\ominus \longrightarrow \text{CH}_3\text{Nu} + \text{Br}^\ominus$
Nucleophile Reactivity in SN2 Reactions
The reaction provided is an SN2 (Substitution Nucleophilic Bimolecular) process:
$ \text{CH}_3\text{Br} + \text{Nu}^\ominus \longrightarrow \text{CH}_3\text{Nu} + \text{Br}^\ominus $
The reaction rate is influenced by the nucleophilicity of the attacking species ($\text{Nu}^\ominus$). The nucleophiles to compare are: acetate ($\text{CH}_3\text{COO}^-$), phenoxide ($\text{PhO}^-$), hydroxide ($\text{}^-\text{OH}$), and perchlorate ($\text{ClO}_4^-$).
Nucleophile Strength Analysis
We analyze the factors affecting nucleophilicity for each species to establish the rate order.
- Perchlorate ($\text{ClO}_4^-$): It is highly resonance-stabilized and the conjugate base of a strong acid ($\text{HClO}_4$). This makes it a very weak base and a negligible nucleophile.
- Hydroxide ($\text{}^-\text{OH}$): A strong base, typically a good nucleophile. However, its small size results in strong solvation in protic solvents, which can hinder its attack.
- Phenoxide ($\text{PhO}^-$): Resonance delocalization into the benzene ring reduces basicity and nucleophilicity compared to hydroxide. It experiences less solvation than hydroxide.
- Acetate ($\text{CH}_3\text{COO}^-$): Resonance delocalization between the two oxygen atoms occurs. It's a stronger base than phenoxide.
Based on the provided correct answer, the observed nucleophilicity order is:
$ \text{CH}_3\text{COO}^- > \text{PhO}^- > \text{}^-\text{OH} > \text{ClO}_4^- $
This order suggests that in this context, acetate is the most effective nucleophile, followed by phenoxide, then hydroxide, and perchlorate is the least effective. This reflects a complex interplay of basicity, resonance, and solvation effects.
Rate Order Determination
In an SN2 reaction, the rate depends directly on the nucleophile's ability to attack the electrophilic carbon.
$ \text{Rate} \propto \text{Nucleophilicity} $
Therefore, the correct order of the rate of reaction concerning the nucleophiles is:
$ \text{CH}_3\text{COO}^- > \text{PhO}^- > \text{}^-\text{OH} > \text{ClO}_4^- $
Similar Questions
- In Dumas method for estimation of nitrogen, 0.50 g of an organic compound gave 70 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage of nitrogen in the organic compound is ______ %.
(Aqueous tension at 300 K is 15 mm). Given below are two statements:
Statement I: The dipole moment of R-CN is greater than R-NC and R-NC can undergo hydrolysis under acidic medium to produce
Statement II: R-CN hydrolyses under acidic medium to produce a compound which on treatment with $\text{SOCl}_2$, followed by the addition of $\text{NH}_3$ gives another compound(x). This compound (x) on treatment with $\text{NaOCl/NaOH}$ gives a product, that on treatment with $\text{CHCl}_3\text{/KOH/}\Delta$ produces R-NC
In the light of the above statements, choose the correct answer from the options given below- Given below are two statements:
Statement I: Cross aldol condensation between two different aldehydes will always produce four different products.
Statement II: When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.
In the light of the above statements, choose the correct answer from the options given below - $0.25 \text{ g}$ of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of $\text{CaCl}_2$ tube and potash tube at the end of the experiment. The amount was found to be $0.15 \text{ g}$ and $0.1837 \text{ g}$, respectively. The percentage of oxygen in compound A is ______ %. (Nearest integer)
(Given: molar mass in $\text{g mol}^{-1}$ $\text{H} : 1, \text{C} : 12, \text{O} : 16$) - Grignard reagent $\text{RMgBr (P)}$ reacts with water and forms a gas $\text{(Q)}$. One gram of Q occupies $1.4 \text{ dm}^3$ at STP. (P) on reaction with dry ice in dry ether followed by $\text{H}_3\text{O}^+$ forms a compound $\text{(Z)}$. 0.1 mole of $\text{(Z)}$ will weigh _________ g. (Nearest integer)
- Given below are four compounds :
(a) n-propyl choride
(b) iso-propyl chloride
(c) sec-butyl chloride
(d) neo-pentyl chloride
Percentage of carbon in the one which exhibits optical isomerism is : - The correct statements are :
A. Activation energy for enzyme catalysed hydrolysis of sucrose is lower than that of acid catalysed hydrolysis.
B. During denaturation, secondary and tertiary structures of a protein are destroyed but primary structure remains intact.
C. Nucleotides are joined together by glycosidic linkage between $\text{C}_1$ and $\text{C}_4$ carbons of the pentose sugar.
D. Quaternary structure of proteins represents overall folding of the polypeptide chain.
Choose the correct answer from the options given below : - By usual analysis, $1.00\text{ g}$ of compound (X) gave $1.79\text{ g}$ of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : __________ (nearest integer)
(Given, molar mass in $\text{g\ mol}^{-1}$ : $\text{O} = 16, \text{Mg} = 24, \text{P} = 31$) Given below are two statements :
Statement I : Compound (X), shown below, dissolves in $\text{NaHCO}_3$ solution and has two chiral carbon atoms
Statement II : Compound (Y), shown below, has two carbons with $\text{sp}^3$ hybridization, one carbon with $\text{sp}^2$ and one carbon with $\text{sp}$ hybridization
In the light of the above statements, choose the correct answer from the options given below :
Consider the above sequence of reactions. The number of bromine atom(s) in the final product (P) will be :
Important Questions from Organic Chemistry
- In Dumas method for estimation of nitrogen, 0.50 g of an organic compound gave 70 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage of nitrogen in the organic compound is ______ %.
(Aqueous tension at 300 K is 15 mm). Given below are two statements:
Statement I: The dipole moment of R-CN is greater than R-NC and R-NC can undergo hydrolysis under acidic medium to produce
Statement II: R-CN hydrolyses under acidic medium to produce a compound which on treatment with $\text{SOCl}_2$, followed by the addition of $\text{NH}_3$ gives another compound(x). This compound (x) on treatment with $\text{NaOCl/NaOH}$ gives a product, that on treatment with $\text{CHCl}_3\text{/KOH/}\Delta$ produces R-NC
In the light of the above statements, choose the correct answer from the options given below- Given below are two statements:
Statement I: Cross aldol condensation between two different aldehydes will always produce four different products.
Statement II: When semicarbazide reacts with a mixture of benzaldehyde and acetophenone under optimum pH, it forms a condensation product with acetophenone only.
In the light of the above statements, choose the correct answer from the options given below - $0.25 \text{ g}$ of an organic compound "A" containing carbon, hydrogen and oxygen was analysed using the combustion method. There was an increase in mass of $\text{CaCl}_2$ tube and potash tube at the end of the experiment. The amount was found to be $0.15 \text{ g}$ and $0.1837 \text{ g}$, respectively. The percentage of oxygen in compound A is ______ %. (Nearest integer)
(Given: molar mass in $\text{g mol}^{-1}$ $\text{H} : 1, \text{C} : 12, \text{O} : 16$) - Grignard reagent $\text{RMgBr (P)}$ reacts with water and forms a gas $\text{(Q)}$. One gram of Q occupies $1.4 \text{ dm}^3$ at STP. (P) on reaction with dry ice in dry ether followed by $\text{H}_3\text{O}^+$ forms a compound $\text{(Z)}$. 0.1 mole of $\text{(Z)}$ will weigh _________ g. (Nearest integer)
