ORGANIC CHEMISTRY

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Chapter 2

2.5 Functional Groups

官能团

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

Functional groupsThe structural features that make it possible to classify compounds by reactivity are called functional groups.A functional group is a part of a larger molecule and is composed of an atom or a group of atoms that have a characteristic chemical behavior.The Chemistry of every organic molecules, regardless of size and complexity, is determined by the functional groups it contains.

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.5A Alkyl Group and the Symbol RAlkyl groups (烷基) are the groups that we identify for purposes of naming compounds.They are groups that would be obtained by removing a hydrogen atom from an alkaneR is used as a general symbol to represent any alkyl group.

CH4 CH3 Me MethylCH3CH3 CH3CH2 Et

CH3CH2CH3 CH3CH2CH2

CH3CH2CH3 CH3CHCH3

Pr

i-Pr

C2H5

(CH3)2CH

or

or

EthylPropyl

Isopropyl

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Department of Chemistry, Xiamen University

Chapter 2

2.5B Phenyl and Benzyl GroupsPhenyl group (苯基)

C6H5 Ph φ

Ar (if ring substitutents are present)

Benzyl group (苄基)

CH2 CH2 C6H5CH2 Bn

ORGANIC CHEMISTRY

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Chapter 2

2.6 Alkyl Halides or Haloalkanes

烷基卤或卤代烷

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Department of Chemistry, Xiamen University

Chapter 2

Alkyl halides (haloalkanes) are compounds in which a halogen atom (F, Cl, Br, or I) replaces a hydrogen atom of an alkane.

CH3CH3 CH3CH2Cl CH3CH2CH3 CH3CHCH3

BrEthaneAn alkane

Ethyl chlorideAn alkyl halide

Alkyl halides are classified as being primary (伯，一级) (1°), secondary(仲，二级) (2°), or tertiary(叔，三级) (3°) — based on the carbon atom to which the halogen is directly attached.

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Department of Chemistry, Xiamen University

Chapter 2

CCH3

H

H

Cl CCH3

CH3

H

Cl CCH3

CH3

CH3

Cl

Primary carbon atomPrimary carbon atom Secondary carbon atomSecondary carbon atom Tertiary carbon atomTertiary carbon atom

Primary alkyl halide Secondary alkyl halide Tertiary alkyl halide

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.7 Alcohols

醇类

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Department of Chemistry, Xiamen University

Chapter 2

The characteristic functional group of alcoholsis the hydroxyl group (–OH) attached to an sp3-hybridized carbon atom.

C OH Hydroxyl group (羟基)

Alcohols are classified into three groups:Primary (1°) alcohols (伯醇或一级醇)Secondary (2°) alcohols (仲醇或二级醇)Tertiary (3°) alcohols (叔醇或三级醇)

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

Primary carbon atomPrimary carbon atom Secondary carbon atomSecondary carbon atom

CCH3

H

H

OH CCH3

CH3

H

OH CCH3

CH3

CH3

OH

Tertiary carbon atomTertiary carbon atom

Primary alcohol Secondary alcohol Tertiary alcohol

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.8 Ethers

醚类

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Department of Chemistry, Xiamen University

Chapter 2

An ether is a substance that has two organic residues bonded to the same oxygen atom.The organic residues may be alkyl, aryl, or vinylic, and the oxygen atom can be part of either an open chain or a ring.

R O R'R,R' = H R' = R, alkyl, aryl, vinyl

CH3CH2 O CH2CH3 O CH3 H2C CH2

O

ODiehtyl ether

乙醚Anisole

(methyl phenyl ether)茴香醚

Ethylene oxide环氧乙烷

Tetrahydrofuran(THF)四氢呋喃

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.9 Amines

胺类

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Chapter 2

Amines may be considered as organic derivatives of ammonia.

H N HH

R N HH

C6H5CH2CHCH3

NH2

H2NCH2CH2CH2CH2NH2

Ammonia An amine Amphentamine安非他命

Putrescine腐胺

Amines are classified as primary, secondary, or tertiary amines — based on the number of organic groups that are attached to the nitrogen atom.

R N HR'

R N HH

R N R"R'

A primary amine A secondary amine A tertiary amine伯胺，一级胺 仲胺，二级胺 叔胺，三级胺

ORGANIC CHEMISTRY

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Chapter 2

2.10 Aldehydes and Ketones

醛和酮

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Chapter 2

Aldehydes and ketones both contain the carbonyl group (羰基) — a group in which a carbon atom has a double bond to oxygen.

C O

The carbonyl group

Aldehydes

Ketones

R C HO

R C R'O

R C RO

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.11 Carboxylic Acids, Amides, and Esters

羧酸、酰胺和酯

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Chapter 2

2.11A Carboxylic acids

Carboxylic acids have the general formula:

R C OHO

or RCOOH or RCO2H

A carboxylic acid

The functional group is the carboxyl group (羧基).

C OHO

The carboxyl group

or －COOH or －CO2H

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.11B AmidesAmides have the formulas RCONH2, RCONHR’, or RCONR’R”.

R C NH2

OR C NHR'

OR C N

OR'

R"

CH3 C NH2

OC NHCH3

OH C N(CH3)2

O

N-methylbenzamide N,N-dimethylformamideacetamide(DMF)

乙酰胺 N-甲基苯甲酰胺 N,N-二甲基甲酰胺

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.11C EstersEsters have the general formula RCO2R’.

R C OR'O

or RCOOR' or RCO2R'

CH3 C OCH2CH3

O

Ethyl acetate

C OCH3

O

Methyl benzoate

ORGANIC CHEMISTRY

Department of Chemistry, Xiamen University

Chapter 2

2.12 Nitriles

腈类

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Department of Chemistry, Xiamen University

Chapter 2

Compounds containing the –CN functional group are called nitriles.

C N

sp3 hybridized

Acyclic nitriles are named by adding the suffix nitrile to the name corresponding hydrocarbon.

(acetonitrile)

C NCH3

EthanenitrileC NCHCH2

Propenenitrile(acrylonitrile)

Cyclic nitriles are named by adding the suffix carbonitrile to the name of the ring system to which the –CN group is attached.

C N C N

Benzenecarbonitrile Cyclohexanecarbonitrile