Chemistry

Functional Groups

Organic Chemistry

The study of carbon-containing compounds Carbon atoms are the most versatile building

blocks of molecules With a total of 6 electrons, a carbon atom has

2 in the first shell and 4 in the second shell Carbon usually completes its valence shell by

sharing electrons with other atoms in four covalent bonds

This tetravalence by carbon makes large, complex molecules possible

Carbon Chains

form the skeletons of most organic molecules

the skeletons may vary in length and may be straight, branched, or arranged in closed rings

the carbon skeletons may also include double bonds

Isomers

Structural isomers Geometric isomers Enantiomers

Structural Isomers Variation in covalent partners

Pentane has a straight skeleton and isopentane

has a branched skeleton

Same molecular formula C5H12

Geometric Isomers

Variation in arrangement about a double bond

Example: rhodopsin (in the retina) from one geometric isomer to another

Enantiomers

Variation in spatial arrangement, mirror images

enantiomers are possible if there are four different atoms or groups of atoms bonded to a carbon

they are like left-handed and right-handed versions

usually one is biologically active, the other inactive

Functional Group

A specific configuration of atoms commonlyattached to the carbon skeletons of organic molecules and usually involved in chemical reactions

Hydroxyl -OH

Carbonyl CO

Carboxyl -COOH

Amino -NH2

Sulfhydryl -SH

Phosphate -PO4-2 (-OPO3

-2)

Methyl -CH3

1.Hydroxyl Group (-OH)

a hydrogen atom forms a polar covalent bond with an oxygen which forms a polar covalent bond to the carbon skeleton

Organic compounds with hydroxyl groups are alcohols and their names typically end in –ol example ethanol

2.Carbonyl Group ( CO)

consists of an oxygen atom joined to the carbon skeleton by a double bond

ketone - if not at the end example: acetone

aldehyde -if the carbonyl group is on the end of the skeleton example: propanal

3.Carboxyl Group (-COOH) carbon atom with a double bond

with an oxygen atom and a single bond to a hydroxyl group.

carboxylic acids – compounds with carboxyl groups

Acidic properties - because the combined electro negativities of the two adjacent oxygen atoms increase the dissociation of hydrogen as an ion (H+) Example: acetic acid (vinegar)

4. Amino Group (-NH2)

Nitrogen atom attached to twohydrogen atoms and the carbon skeleton.

Amines - Organic compounds with amino groups.

Basic properties - because ammonia can pick up a hydrogen ion (H+) from the solution Example: amino acids

5. Sulfhydryl Group (-SH)

sulfur atom bonded to a hydrogen atom and to the backbone

thiols - organic molecules with sulfhydryl

Sulfhydryl groups help stabilize the structure of proteins Example: amino acid Cysteine

6. Phosphate Group (-OPO3

-2)

Phosphorus bound to four oxygen atoms (three with single bonds and one with a double bond). Phosphate groups are anions with two negative charges as two protons have dissociated from the oxygen atoms. One function of phosphate groups is to transfer energy between organic molecules.

Example ATP

7. Methyl Group (-CH3)

Carbon bonded to 3 hydrogen atoms. The methyl group may be attached to a or a different atom.

Addition of methyl to

molecule changes its shape and function Example: 5-Methyl cytidine

Activity Identify the functional groups

C - NH

H

H

H

HMethylamine

N - C - C O

OH

H

CH3

H

H

Alanine

ActivityIdentify the functional groups

ATP (adenosine triphosphate)

The End