Ch 13Amines — Class 12 Chemistry, concept-first.

Amines are organic compounds containing nitrogen, and their defining chemical character is basicity, arising from the lone pair of electrons that nitrogen carries even after bonding.

Amines are classified along two independent axes. The first axis counts how many of ammonia's three hydrogen atoms have been replaced by an alkyl or aryl group: replace one hydrogen and the result is…

Like most organic functional-group families, amines can be named under either of two systems: an older common-name system (13.2.1), built from the names of the groups attached to nitrogen, and the mod…

Under the common-name system, an aliphatic amine's name is built simply as 'alkyl amine' -- the name of the attached alkyl group, followed directly by the suffix '-amine' (for example, ethyl plus amin…

Under the IUPAC system, a PRIMARY amine's name is built by taking the name of the parent alkane, replacing its final '-e' with the suffix '-amine' (giving the family name 'alkanamine'), and adding a l…

Amines can be built up in the laboratory from several different starting functional groups, each requiring its own named reaction: alkyl halides (by ammonolysis, 13.3.1), nitro compounds (by reduction…

When an alkyl halide is heated with an excess of alcoholic ammonia solution, it undergoes nucleophilic substitution in which the halogen atom is displaced by an amino (-NH2) group, giving a primary am…

Both aliphatic and aromatic nitro compounds can be reduced all the way to the corresponding primary amine, and this reduction can be carried out by any of three broad reagent choices.

An alkyl cyanide (also called an alkanenitrile), reduced with sodium metal dissolved in ethanol, gives a primary amine -- this specific combination of reagents is a named reaction, the Mendius reducti…

Primary amines having the SAME number of carbon atoms as the starting material can be obtained by reducing an amide, using either lithium aluminium hydride dissolved in dry ether, or sodium dissolved…

The Gabriel phthalimide synthesis is a method specifically for making PRIMARY amines, and it proceeds through three distinct stages, each converting one intermediate into the next.

Hofmann degradation -- also called Hofmann rearrangement, Hofmann bromamide degradation, or Hofmann hypobromite degradation, all names for the same reaction -- is described as a genuinely GOOD laborat…

Having covered how amines are made (13.3), this section turns to how they physically behave -- their intermolecular forces, and the boiling points and water solubility that follow from those forces --…

The N-H bond found in primary and secondary amines is a polar bond, because nitrogen (electronegativity 3.0) and hydrogen (electronegativity 2.1) differ noticeably in their pull on the shared bonding…

Amines are basic in character specifically because of the lone pair of electrons carried on their nitrogen atom, and this basicity can be described from two related theoretical viewpoints.

Reading straight off the observed pKb values in Table 13.4, the trend for ammonia and the three classes of aliphatic amine can be written as an order of pKb VALUES: NH3 R-NH2 R2NH < R3N -- and, since…

Reading Table 13.4's arylamine pKb values (aniline 9.38, N-methylaniline 9.30, N,N-dimethylaniline 8.92) against the aliphatic and ammonia values above them (all well under 5), arylamines in general a…

Having covered how amines are basic (13.5), this section turns to the wider range of characteristic chemical reactions amines undergo: laboratory identification tests (13.6.1), repeated (exhaustive) a…

Two distinct laboratory tests for amines are described here. (a) Testing for the amine's basic character: all three classes of amine -- primary, secondary and tertiary alike -- are basic compounds, so…

Hofmann's exhaustive alkylation describes what happens when a primary amine is heated with an EXCESS of a primary alkyl halide: rather than stopping cleanly at a simple substitution product, the react…

When a tetraalkylammonium halide (the quaternary salt reached by exhaustive alkylation, section 13.6.2) is heated together with moist silver oxide, it is converted into the corresponding quaternary am…

Both aliphatic and aromatic PRIMARY and SECONDARY amines undergo acylation reactions, because both classes retain at least one 'replaceable', positively-polarised hydrogen atom directly bonded to nitr…

Both aliphatic and aromatic PRIMARY amines, when heated together with chloroform (CHCl3) in the presence of a base, give a distinctively foul- or offensive-smelling product, generically called an alky…

Primary, secondary and tertiary amines each react differently with nitrous acid (HNO2), but ONLY the reaction of PRIMARY amines is examined in detail in this section.

Aryl diazonium salts, once formed (section 13.6.6b), show two genuinely distinct types of further reaction, depending on whether the diazonium group itself is ultimately kept or lost.

The diazonium group, -N2(+), carried on an arene diazonium salt is a genuinely VERY GOOD leaving group, precisely because of the positive charge sitting on the nitrogen atom directly bonded to the aro…

In direct contrast to section 13.7.1's substitution reactions, arene diazonium salts can also react with certain OTHER, particularly reactive aromatic compounds -- specifically phenols or aromatic ami…

Benzenesulfonyl chloride (C6H5SO2Cl) is given its own specific name in the context of distinguishing amines: Hinsberg's reagent, used in what is correspondingly called the Hinsberg test.

The amino group (-NH2), whether on a primary, secondary or tertiary aromatic amine, is both an ORTHO/PARA-DIRECTING group and a genuinely POWERFUL RING-ACTIVATING group -- because the nitrogen's lone…

The end-of-chapter questions of this group, exactly as the book prints them.

The end-of-chapter questions of this group, exactly as the book prints them.

The end-of-chapter questions of this group, exactly as the book prints them.

The end-of-chapter questions of this group, exactly as the book prints them. (The book numbers this group's items i, ii, iii, iv, v, vii, viii — the printed numbering skips vi.; our running numbers ar…

The end-of-chapter questions of this group, exactly as the book prints them.

Sample papers and previous-year board questions for this subject.