Amines

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Substituted Amines

Amines are nitrogen containing functional groups that can be substituted to form

primary, secondary and tertiary structures.

N

N Cl

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Lone Pairs & Quaternary Amines

Most amines are characterized by a lone pair that plays a major part in amine

chemistry (such as hydrogen bonding and basicity).

A fourth group can bond to nitrogen to form a quaternary ammonium ion,

which is positively charged and helps form ionic compounds.

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Primary alkyl amines are named by identifying the alkyl group attached to nitrogen and adding the

suffix “amine” to the alkyl group name.

Amine Nomenclature: Primary

N CCH

CH3

CH3H

H3C

H3CH N

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For secondary and tertiary amines with the same substituents, add the appropriate prefix, di- or tri-,

to the alkyl group name.

Identically Substituted Amines

diisopropylamine triethylamine

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Differently Substituted Amines

When the R groups in a 2° and 3° amine are different, the compounds are named as N-substituted

derivatives of a 1° amine.

The parent compound is chosen as the 1° amine that contains the largest of R group.

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When NH2 is a substituent on the main chain, it is called an amino group.

Amino Groups and Aniline

Aniline is the common name of an amino-substituted benzene

NH N

H2N

HN

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Name the Following Compounds

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Properties of Amines: Basicity

The lone electron pair on the nitrogen of amines causes them to be weak Bronsted-Lowry bases by forming a

bond with a hydrogen from an acid or water.NH2 + HBr

N+ HCl

H2N + NaOH

Cl

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Reactions of Amines: Acid/Base Chemistry

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Properties of Amines: Boiling Points

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Properties of Amines: Boiling Points

Primary and secondary amines have higher boiling points to comparable alkanes due to

hydrogen bonding.

Tertiary alkanes have lower boiling points than alcohols or other amines of similar MW due to the

lack of hydrogens on nitrogen.

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! Heterocycle: A ring that contains nitrogen or some other atom in addition to carbon.

! Heterocycles are common in many natural compounds found in plants and animals.

Nitrogen Heterocycles

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! Diphenylhydramine hydrochloride (Benadryl), is an over-the-counter antihistamine. Many OTC drugs are sold as the hydrochloride salt.

Chemistry is Cool!

O NH Cl

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!Quaternary ammonium ions have four organic groups bonded to the nitrogen atom. Their structures in solution are unaffected by changes in pH.

!Benzalkonium chlorides have both antimicrobial and detergent properties. They are used in surgical scrubs and for sterile storage of instruments.

Chemistry is Cool!

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! Many alkaloids are physiologically active. ! Caffeine and nicotine are stimulants. ! Others are notable as pain relievers (analgesics), as

sleep inducers, and for the euphoric states they can create.

Alkaloids