Pkb of aniline is lower than the m-nitroaniline

This article may contain excessive or improper use of Please review the use of non-free content according to ( April 2019) ( ( Ortho effect refers mainly to the set of There are three main ortho effects in substituted benzene compounds: [ clarification needed] • Ortho effect in substituted benzoic acid (first ortho effect): Ortho-substituted benzoic acids are stronger acids than their meta and para isomers, regardless of the nature of the substituent • Ortho effect in substituted aniline (second ortho effect/SIP effect): Ortho-substituted anilines are weaker bases than their meta and para isomers, regardless of the nature of the substituent • Ortho effect in electrophilic aromatic substitution of disubstituted benzene compounds (third ortho effect): It refers to the set of steric effects which determines the regioselectivity of an incoming electrophile in disubstituted benzene compounds where a meta-directing group is meta to an ortho–para-directing group. First ortho effect in substituted benzoic acids [ ] When any group is present at ortho to carboxyl group in substituted benzoic acid then the acidic character of that compound becomes at least more than benzoic acid. Generally ortho-substituted benzoic acids are stronger acids than their meta and para isomers also. The table given below shows pKa values of various monosubstituted benzoic acids. • The ortho effect is large for the nitrobenzoic acids, which show nearly a 20 fold increase in acidity, roughly an 8 fold facto...

Give reasons of the following observations: a. Aniline is acetylated before nitration reaction. b. pK b of aniline is lower than the m-nitroaniline. c. Primary amine on treatment with benzenesulphonyl chloride forms a product which is soluble in NaOH however secondary amine gives product which is insoluble in NaOH. d. Aniline does not react with methyl chloride in the presence of anhydrous AlCl 3 catalyst. a. Aniline is acetylated, before nitration reaction in order to avoid formation of tarry oxidation products and protecting the amino group, so that p -nitro derivative can be obtained as major product. b. pK b of aniline is lower than the m-nitro aniline. The basic strength of aniline is more that m-nitroaniline. pk b value is inversely proportional to basic strength. Presence of Electron withdrawing group decrease basic strength. c. Due to the presence of acidic hydrogen in the N-alkylbenzenesulphonamide formed by the treatment of primary amines. d. Aniline does not react with methylchloride in the presence of AlCl 3 catalyst , because aniline is a base and AlCl 3 is Lewis acid which lead to formation of salt.

In this section we consider the relative basicity of several nitrogen-containing functional groups: amines, amides, anilines, imines, and nitriles. When evaluating the basicity of a nitrogen-containing organic functional group, the central question we need to ask ourselves is: how reactive (and thus how basic) is the lone pair on the nitrogen? In other words, how much does that lone pair want to break away from the nitrogen nucleus and form a new bond with a hydrogen? Comparing the basicity of alkyl amines to ammonia Because alkyl groups donate electrons to the more electronegative nitrogen. The inductive effect makes the electron density on the alkylamine's nitrogen greater than the nitrogen of ammonium. Correspondingly, primary, secondary, and tertiary alkyl amines are more basic than ammonia. Comparing the basicity of alkylamines to amides With an alkyl amine the lone pair electron is localized on the nitrogen. However, the lone pair electron on an amide are delocalized between the nitrogen and the oxygen through resonance. This makes amides much less basic compared to alkylamines. In fact,when and amide is reacted with an acid, the protonation occurs at the carbonyl oxygen and not the nitrogen. This is becase the cation resulting from oxygen protonation is resonance stabilised. The cation resulting for the protonation of nitrogen is not resonance stabilized. Basicity of aniline Aniline is substantially less basic than methylamine, as is evident by looking at the pK a v...

Objectives After completing this section, you should be able to • use the concept of resonance to explain why arylamines are less basic than their aliphatic counterparts. • arrange a given series of arylamines in order of increasing or decreasing basicity. • discuss, in terms of inductive and resonance effects, why a given arylamine is more or less basic than aniline. Study Notes With reference to the discussion of base strength, the traditional explanation for the base‑strengthening effect of electron‑releasing (I) substituents is that such substituents help to stabilize the positive charge on an arylammonium ion more than they stabilize the unprotonated compound, thereby lowering ΔG°. The electron‑withdrawing (i.e., deactivating) substituents decrease the stability of a positively charged arylammonium ion. Note that the arylammonium ion derived from aniline, PhNH 3 +, is commonly referred to as the anilinium ion. Basicity of Aniline Aniline is substantially less basic than methylamine, as is evident by looking at the pK a values for their respective ammonium conjugate acids (remember that the lower the pKa of the conjugate acid, the weaker the base). This difference is basicity can be explained by the observation that, in aniline, the lone pair of electrons on the nitrogen are delocalized by the aromatic p system, making it less available for bonding to H + and thus less basic. The lone pair electrons of aniline are involved in four resonance forms making them more stabl...

Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important Important You are here Important Important Important Important Important Important Important Important Important Important Give reasons for any 3 of the following observations: a. Aniline is acetylated before nitration reaction. b. pKb of aniline is lower than the m-nitroaniline. c. Primary amine on treatment with benzenesulphonyl chloride forms a product which is soluble in NaOH however secondary amine gives product which is insoluble in NaOH. d. Aniline does not react with methyl chloride in the presence of anhydrous AlCl 3 catalyst. Answer: a. Aniline is acetylated, before nitration reaction in order to avoid formation of tarry oxidation products and protecting the amino group, so that p -nitro derivative can be obtained as major product. b.pKb of aniline is lower than the m-nitro aniline.The basic strength of aniline is more that m-nitroaniline . pkb value is inversely proportional to basic strength. Presence of Electron withdrawing group decrease basic strength. c. Due to the presence of acidic hydrogen in the N-alkylbenzenesulphonamide formed by the treatment of primary amines. d. Aniline does not react with methylchloride in the presence of AlCl 3 catalyst ,because aniline is a base and AlCl 3 is Lewis acid which lead to formation of salt.

• A discrete series of lines of equal intensity and equally spaced with respect to wavelength • A series of only four lines • A continuous emission of radiation of all frequencies • Several discrete series of lines with both intensityr and spacings between lines decreasing as the wavelength number increases within each series b. pK b ​ of aniline is lower than the m-nitroaniline. c. Primary amine on treatment with benzenesulphonyl chloride forms a product which is soluble in NaOH however secondary amine gives product which is insoluble in NaOH. Updated On Sep 20, 2022 Topic Amines Subject Chemistry Class Class 11 Answer Type Video solution: 1 Upvotes 115 Avg. Video Duration 4 min

Question Updated on: 13/06/2023 Account for the following : (i) p K b of aniline is more than that of methylamine . (ii) Ethylamine is soluble in water, whereas aniline is not. (iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide . (iv) Although amino group is o- and p-directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline. (v) Aniline does not undergo Friedel-Crafts reaction. (i) In aniline, the lone pair of electrons on N atom is delocalized over the benzene ring. As a result, electron density on the nitrogen decreases. On the other hand , in C H 3 N H 2 + I effect of C H 3 group increases the electron density on N atom. Therefore, aniline is less basic than methylamine and hence p k b of aniline is higher than that of methylamine. (ii) Ethylamine dissolves in water due to intermolecular hydrogen bonding as shown below : However , because of large hydrophobic part (i.e. hydrocarbon part) of aniline, the extent of hydrogen bonding is less and therefore, aniline is insoluble in water. (iii) Methylamine is more basic than water and therefore, accepts a proton from water forming O H − ions C H 3 N H 2 + H − O H → C H 3 − N H + 3 + O H − These O H − ions combine with F e 3 + ions to form brown ppt. of hydrate ferric oxide. F e C l 3 → F e 3 + + 3 C l − 2 F e 3 + + 6 O H − → 2 F e ( O H ) 3 or F e 2 O 3 . 3 H 2 O Hydrated ferric hydroxide (Brown ppt) (iv) Under strongl...