The chemistry of carbon compounds. Mainly carbon and hydrogen atoms. Many organic compounds occur naturally. Thousands more can be synthesized by

man.

Ch. 10: Organic Chemistry

Butane versus NaClInorganic Organic

NaCl, 58.5 g/mol Bonding is ionic M.P. = 801oC B.P. = 1413oC Dissolves in water Will not burn

C4H10, 58.1 g/mol Bonding is covalent M.P. = -138oC B.P. = 0oC Not soluble in water Will burn in air

Decide whether the property is that of pentane (C5H12) or sodium sulfide (Na2S).

1. Liquid at room temperature.2. Dissolves in water.3. Floats on the surface of water.4. Has a melting point of 1176oC.5. Burns in air easily.

Learning Check

The bonding in all organic molecules is covalent.

• Carbon has 4 valence electrons and hydrogen has 1.

• • C • H • •

• Carbon achieves an octet by forming four bonds.

Bonding

When carbon is bonded to four other atoms, it has a tetrahedral geometry.

Molecular Geometry

Classes of Organic Compounds

Aliphatic Aromatic

Saturated Unsaturated

Alkanes Cycloalkanes Alkenes Alkynes

Benzene Ring

Molecular formula – shows the number of C and H atoms.

Ex) Propane, C3H8. Complete structural drawing – shows every single

bond. H H H H – C – C – C – H H H H

Methods for Writing Formulas

Condensed structural formula – writes each C atom along with the number of H’s bonded to that carbon atom.

CH3 – CH2 – CH3 This is the preferred method for showing

structures in this course.

Methods for Writing Formulas

A set of rules for naming all organic compounds.

Will not need to memorize the base names. Names for one through ten carbons.

IUPAC Nomenclature

Alkane Base Names

Butane, C4H10, has more than one possible way to put four carbons together.

These two forms are called structural isomers.

Both can NOT be called butane!

Branched Alkanes

A substituent is any group that is attached to the longest chain of carbon atoms.

CH4 = methane, -CH3 = methyl CH3CH3 = ethane, -CH2CH3 = ethyl Cl = chloro, Br = bromo, I = iodo

IUPAC Nomenclature

1. Determine the longest continuous chain of carbon atoms. Because the alkanes have free rotation, the chain may bend and twist in many shapes!

2. Determine the type of substituents located on the longest chain. These are named in alphabetical order.

IUPAC Nomenclature

3. Number the longest chain such that the substituents have the lowest numbers.

4. Name the substituents first followed by the base name. If two or more of the same substituent, then use prefixes.

5. Every substituent MUST have a number in front of it indicating the position on the chain.

IUPAC Nomenclature

A ring structure can be constructed from alkanes of three or more carbons by removing two hydrogen atoms.

Because they form a geometric shape, a shorthand method for their structure is that shape.

Cycloalkanes

For ring structures, a mono-substituted ring does not need a number.

Why??? For di-substituted ring structures, number

starting from the location of one the substituents and then go CW or CCW to give the next one the lowest number.

IUPAC Nomenclature

A haloalkane is placing a halogen (group 7A) atom in place of a hydrogen atom.

Naming uses the fluoro, chloro, bromo, and iodo names.

Haloalkanes are used as refrigerants (CF3CH2F) and anesthetic agents (CF3CHClBr).

Haloalkanes

When converting a name to a condensed formula, you may want to do it in several steps.

1. Base name = carbon backbone.2. Fill in substituent groups.3. Add H’s until each carbon has four bonds.4. Condense.

Names to Formulas

Alkanes are non-polar and, thus, do NOT dissolve in water.

Alkanes typically have a density of 0.65 – 0.70 g/mL and will float on the surface of water.

All alkanes can be burned to produce energy.

Alkane + O2 CO2 + H2O

Properties of Alkanes

Crude oil contains a variety of alkanes that are separated at an oil refinery.

The mixture is heated and then separated by fractions – that is, their differences in boiling points.

The lightest alkanes have the lowest boiling points and go to the top of the column.

Crude Oil

Crude Oil

Crude Oil

Alkanes are fairly unreactive and have little use to organic chemists.

Addition of other atoms like O, N, and S change the reactivity and properties of the boring alkanes and these are called functional groups.

Functional groups are classified into several common identifiers.

Functional Groups

Use of the letter “R” in generic formulas.

Alcohol – contain the hydroxyl (O-H) group.

R-OH Ex) CH3CH2OH, CH3CHCH3

OH

Functional Groups

Ether – an oxygen atom separating two alkyl groups.

R – O – R’ Ex) CH3CH2-O-CH2CH3

Carbonyl group, C=O, is found in a couple of different ways.

Functional Groups

Aldehyde – the carbonyl group is on the end of the chain.

RCHO Ex) CH3CH2C=O

H

Functional Groups

Ketone – the carbonyl group is in the middle of the chain.

R(C=O)R’ Ex) CH3 – C – CH3

O

Functional Groups

Carboxylic acid – has both the carbonyl and the hydroxyl groups.

RCOOH Ex) CH3 – C – OH

O

Functional Groups

Ester – combines the carbonyl group and the ether group.

R-COO-R’ Ex) CH3CH2CH2 – C – O – CH3

O

Functional Groups

Amine – is a nitrogen atom that can be bonded to one, two, or three alkyl groups.

RNH2 , R2NH, and R3N (note: R groups can be different!).

Ex) CH3 – NH2 , (CH3)3N

Functional Groups

Thiol – is a sulfur atom with one H atom (usually).

R-SH CH3CH2 – SH

Functional Groups

Alkenes, alkynes, and aromatics can also be considered as a functional group.

All of these will be discussed in greater details in the following chapters including naming, properties, and important reactions.

Functional Groups