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>> $Chemical Reactions of Carboxylic Acids$

Chemical Reactions of Carboxylic Acids

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Acidity of carboxylic acids

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Reactions Involving Cleavage of C-OH Bond

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Reactions involving -COOH Group

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Substitution Reactions in Hydrocarbon Part

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Q: Arrange the following compounds in increasing order of their property as indicated:(i) Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN)(ii) \$CH_3CH_2CH(Br)COOH,\ CH_3CH(Br)CH_2COOH,\ (CH_3)_2CHCOOH,\ CH_3CH_2CH_2COOH\$ (acid strength)(iii) Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid,4-Methoxybenzoic acid (acid strength)

(i) With increase in +I effect of alkyl groups or increase in the steric hindrance (to the nucleophilic attack by cyanide ion at carbonyl carbon), the reactivity towards HCN addition decreases. Hence, the increasing order of the reactivity towards HCN is Di-tert-butyl ketone > Methyl tert-butyl ketone > Acetone > Acetaldehyde.(ii) The acid strength of carboxylic acid decreases due to +I effect and increases due to -I effect. Isoprpopyl group has higher +I effect than n propyl group. Hence, 2-methyl propanoic acid is weaker acid than butanoic acid.With increase in distance, -I effect decreases. Hence, the acid strength of 2-bromobutanoic acid is higher than the acid strength of 3-bromobutanoic acid.Hence, the increasing order of acid strength is \$\displaystyle (CH_3)_2CHCOOH < CH_3CH_2CH_2COOH < CH_3CH(Br)CH_2COOH \$ \$< CH_3CH_2CH(Br)COOH\$.(iii) Acid strength decreases due to presence of electron donating groups. Hence, 4-methoxybenzoic acid has lower acid strength than benzoic acid.Acid strength increases due to presence of electron withdrawing group. Hence, the acid strength of benzoic acid is lower than the acid strength of 4-nitrobenzoic acid and 3,4-dinitrobenzoic acid. The acid strength of 3,4-ditrobenzoic acid is higher than the acid strength of 4-nitrobenzoic acid due to presence of second nitro group in the meta position to carboxylic group. The increasing order of acid strength is as follows:\$\displaystyle 4-methoxybenzoic acid < benzoic acid < 4-nitrobenzoic acid < 3,4-dinitrobenzoic acid\$

Q: Which of the following is most reactive towards electrophilic substitution reaction?

\$(A)\$ \$Phenol\$The rate of electrophilic substitution reaction is directly proportional to nucleophilicity of Benzene ring. The group which increase the electron density in benzene ring i.e. electron donating group increase the nucleophilicity of Benzene ring which results in an increase in the rate of reaction towards electrophilic substitution \$Rn^n\$ . In series of activating group \$OH\$ comes first then \$OCH_3\$, hence, phenol is most reactive towards electrophilic substitution reaction.

Q: Chloroacetic acid is a stronger acid than acetic acid. Give one reason.

Chloroacetic acid \$ \displaystyle Cl-CH_2-COOH\$ is strongest acid than acetic acid \$ \displaystyle CH_3-COOH\$. \$ \displaystyle -Cl\$ is electron withdrawing group. It increases the acidity of acetic acid by dispersing negative charge by inductive effect and stabilizing the acetate anion.

Q: The increasing order of acidic strength in the following acids. \$ClCH_{2} COOH, CH_{3}CH_{2}COOH,ClCH_{2}CH_{3}COOH,(CH_{3})_{2}CHCOOH\$ and \$CH_{3}COOH\$ is:

Electron donating group decreases the strength of the acid Electron withdrawing group increases the strength of the acid Since \$-CH_{3} \$ is an electron-donating group, it decreases the acidity\$\therefore (CH_{3})_{2}CHCOOH < CH_{3}CH_{2}COOH < CH_{3}COOH\$\$-Cl \$ is an electron withdrawing group, it increases the acidity \$ \therefore ClCH_{2}CH_{2}COOH < ClCH_{2}COOH\$The increasing order of acid strength is \$ \therefore (CH_{3})_{2}CHCOOH < CH_{3}CH_{2}COOH < ClCH_{2}CH_{2}COOH< CH_{3}COOH<ClCH_{2}COOH \$

Q: Arrange the following compounds in decreasing order of their acidic character.\$CH_3CH_2OH, CH_3COOH, ClCH_2COOH, FCH_2COOH, C_6H_5CH_2COOH\$

The order of their electron withdrawing capability is :\$ -F^- > -Cl^- > C_6H_5 > CH_3 > alcohols\$Thus the acidity order is : \$FCH_2COOH > ClCH_2COOH > C_6H_5CH_2COOH > CH_3COOH > CH_3CH_2OH\$

Q: Which of the following compound has highest acidic strength?

option C is most acidic molecule because of the ortho effect of the nitro group and also, it is an electron withdrawing group unlike methyl group. Thus reduces the electron density at carbonyl carbon and increases the acidity of carboxylic acid.

Q: The strongest acid among the following acids is :

Among the given acids, formic acid is the strongest acid.As the number of methyl groups increases, the electron releasing +I effect of substituents decreases the acidity of carboxylic acids by intensifying the negative charge by inductive effect and destabilizing the carboxylate anion.

Q: Arrange the following in decreasing order of acidic strength.I. Benzoic acidII. 4-nitrobenzoic acidIII. 3, 4-dinitrobenzoic acidIV. 4-methoxy benzoic acid

Since, electron donating groups decreases the acid strength, therefore, 4-methoxy benzoic acid is a weaker acid than benzoic acid. Further, since electron-withdrawing groups increase the acid strength, therefore, both 4-nitrobenzoic acid and 3, 4-dinitrobenzoic acid are stronger acid than benzoic acid.Further, due to presence of an additional \$N{ O }_{ 2 }\$ at \$m\$-position with respect to \$COOH\$ group, 3, 4-dinitrobenzoic acid thus the overall acid strength increase in the order:4-methoxy benzoic acid < benzoic acid < 4-nitrobenzoic acid < 3, 4-dinitrobenzoic acid.

Q: Arrange the following compounds in increasing order of their property as indicated.(i) \$CH_{3}COCH_{3},C_{6}H_{5}COCH_{3},CH_{3}CHO\$ (reactivity towards nucleophilic addition reaction)(ii) \$CI-CH_{2}-COOH,F-CH_{2}-COOH,CH_{3}-COOH\$ (acidic character).

(i) Nucleophiles are negatively entity positivity of carbon is carbonyl group facilitates nucleophilic addition. Thus, positivity of carbon in carbonyl carbon is so much decrease than \$(I)\$ and \$(II)\$. Thus, nucleophilic addition order \$III>I>II\$.(ii) The stability order \$II>I>III\$, due to \$+I\$ effect of \$ CH_3\$ group electron density of oxygen is more. But in (I) and (II), \$-I\$ effect of \$F\$ is more than \$Cl\$. Thus, II is more stabilized than I. Thus, acidity order is \$II>I>III\$.

Acidic Nature of Carboxylic Acids

19 mins

Reactions involving Cleavage of C-OH bond in Carboxylic Acids

16 mins

Reactions Involving -COOH group

17 mins

Electrophilic Substitution Reactions of Carboxylic Acids

6 mins

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Arrange the following compounds in increasing order of their property as indicated.
(i) $C H_{3} C O C H_{3}, C_{6} H_{5} C O C H_{3}, C H_{3} C H O$ (reactivity towards nucleophilic addition reaction)
(ii) $C I - C H_{2} - C O O H, F - C H_{2} - C O O H, C H_{3} - C O O H$ (acidic character).

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Revise with Concepts

Acidity of carboxylic acids

Reactions Involving Cleavage of C-OH Bond

Reactions involving -COOH Group

Substitution Reactions in Hydrocarbon Part

Learn with Videos

Quick Summary With Stories

Acidic Nature of Carboxylic Acids

Reactions of COOH Group - OH Bond Breaking

Reactions of COOH Group - C-O Bond Breaking - I

Reactions of COOH Group - C-O Bond Breaking - II

Reactions involving -COOH Group

Electrophilic Substitution Reactions of Carboxylic Acids

Which of the following is most reactive towards electrophilic substitution reaction?

Chloroacetic acid is a stronger acid than acetic acid. Give one reason.

The increasing order of acidic strength in the following acids. ClCH2​COOH,CH3​CH2​COOH,ClCH2​CH3​COOH,(CH3​)2​CHCOOH and CH3​COOH is:

Arrange the following compounds in decreasing order of their acidic character. CH3​CH2​OH,CH3​COOH,ClCH2​COOH,FCH2​COOH,C6​H5​CH2​COOH

Which of the following compound has highest acidic strength?

Benzoic acid does not undergo Friedel-Crafts reaction due to ------ of the benzene ring by the ------ effect of −COOH group.

The strongest acid among the following acids is :

Arrange the following in decreasing order of acidic strength. I. Benzoic acid II. 4-nitrobenzoic acid III. 3, 4-dinitrobenzoic acid IV. 4-methoxy benzoic acid

Arrange the following compounds in increasing order of their property as indicated. (i) CH3​COCH3​,C6​H5​COCH3​,CH3​CHO (reactivity towards nucleophilic addition reaction) (ii) CI−CH2​−COOH,F−CH2​−COOH,CH3​−COOH (acidic character).

The increasing order of acidic strength in the following acids. $C l C H_{2} C O O H, C H_{3} C H_{2} C O O H, C l C H_{2} C H_{3} C O O H, (C H_{3})_{2} C H C O O H$ and $C H_{3} C O O H$ is:

Arrange the following compounds in decreasing order of their acidic character.
$C H_{3} C H_{2} O H, C H_{3} C O O H, C l C H_{2} C O O H, F C H_{2} C O O H, C_{6} H_{5} C H_{2} C O O H$

Benzoic acid does not undergo Friedel-Crafts reaction due to ------ of the benzene ring by the ------ effect of $- C O O H$ group.

Arrange the following in decreasing order of acidic strength.
I. Benzoic acid
II. 4-nitrobenzoic acid
III. 3, 4-dinitrobenzoic acid
IV. 4-methoxy benzoic acid

Arrange the following compounds in increasing order of their property as indicated.
(i) $C H_{3} C O C H_{3}, C_{6} H_{5} C O C H_{3}, C H_{3} C H O$ (reactivity towards nucleophilic addition reaction)
(ii) $C I - C H_{2} - C O O H, F - C H_{2} - C O O H, C H_{3} - C O O H$ (acidic character).