3.11

This set of flashcards covers key concepts about amines, their reactions, properties, solubility, and their roles in different chemical processes.

Why are amines so reactive?

The lone pair of electrons on the Nitrogen due to polar N-H bond.

What kind of intermolecular forces do amines have? Why?

Hydrogen bonding due to the polar N-H bond and lone pair of electrons on the N atom.

Do amines have intermolecular forces which are stronger or weaker than alcohols? Why?

Weaker, as N has a lower electronegativity than O, leading to weaker hydrogen bonding.

Which primary amines are soluble in water/alcohols? Why?

Up to 4 carbon atoms, as they can hydrogen bond to water molecules. Beyond this, non-polarity of the hydrocarbon chain makes them insoluble.

What is the solubility of phenylamine? Why?

Not very soluble, due to the non-polarity of the benzene ring, which cannot form hydrogen bonds.

How can amines act as nucleophiles?

When they bond with an electron-deficient carbon atom by donating the lone pair from N.

What is the product from the basic action of an amine with water?

RNH3+, which is an ammonium ion that forms a salt with an anion.

Is the ammonium ion soluble in water? Why?

Yes, because it is ionic and attracted to the polar bonds in H2O.

How can you regenerate the soluble amine from the ammonium salt?

By adding a strong base like NaOH, which removes H+ ions from the ammonium ion.

In order to be the strongest base, what must a particular amine have?

The greatest electron density around the N atom, making it a better electron pair donor.

What does the positive/negative inductive effect mean?

Positive inductive effect means donating electrons to increase density around N; negative means removing electrons to decrease density around N.

What effect do alkyl groups have on electron density and base strength?

Positive inductive effect, increasing electron density around N, thus making it a stronger base.

What effect do aryl groups have on electron density and base strength?

Negative inductive effect, decreasing electron density around N, thus making it a weaker base.

Order these in terms of base strength: NH3, 1o amine, 2o amine, phenylamine.

2o amine > 1o amine > NH3 > phenylamine.

How do primary amines form 2o, 3o amines and 4o ammonium ions?

Through multiple substitutions, where a primary amine acts as a nucleophile that attacks the original haloalkane.

What are the problems with this method of forming amines?

It's not efficient due to low yield of 1o amine from multiple substitutions.

What conditions are needed to form a nitrile from a primary amine? What is the product formed?

Ethanol as a solvent; a nitrile is formed.

How do you get from a nitrile to a primary amine?

Through reduction using Nickel/Hydrogen catalyst.

What conditions are needed to form nitrobenzene from benzene?

Concentrated H2SO4 and HNO3 to form the NO2+ ion for electrophilic attack.

How do you form an ammonium chloride salt from nitrobenzene? What conditions are needed?

Reduce the nitrile using Tin/HCl at room temperature, forming an ammonium salt with Cl- ions.

What are cationic surfactants?

Quaternary ammonium salts, with a cation that is charged at one end (N+) and non-polar at the other.”},{