Hydrocarbon Derivatives:

Halocarbons, Alcohols, & Ethers

Hydrocarbons

• Contain only carbon & hydrogen

• But carbon can form strong covalent bonds to other elements, incl. O, N, F, Cl, Br, I, S, & P

Functional Group

• One or more H’s in a hydrocarbon can be replaced by an atom or group of atoms.

• An atom or group of atoms in an organic molecule that always behaves in the same way is called a functional group.

• Adding a functional group changes the chemical & physical properties in specific ways, depending on the functional group.

Intermolecular Forces

• Determine Boiling Point & Solubility• Van der Waals or dispersion – nonpolar –

weakest.• Dipole-dipole – intermediate. Molecule

must have atoms with different electronegativities & notnot arranged symmetrically.

• Hydrogen bonding – strongest. Molecules must contain H bonded to F, O, or N.

Functional Groups

• Halocarbons• Alcohols• Ethers• Amines• Aldehydes• Ketones• Carboxylic Acid• Ester

• Amide• Amino Acid

Organic Halides

• One or more of the hydrogen atoms in an alkane is replaced with a halogen (F, Cl, Br, or I).

• NotNot hydrocarbons! Often called halocarbons or alkyl halides.

Naming Halides

• Figure out the base name.

• Use prefixes to specify substituent: fluoro, chloro, bromo, iodo

• If more than one, use di, tri, etc. to specify # of substituents.

• If necessary, give locations of halogens by numbering C-atoms in backbone.

CH3Cl CH3CHFCH3

H H–C–Cl H

chloromethane

H H HH–C–C–C–H H F H

2-fluoropropane

C3H7F

Naming Halides

CH3CCl2CHClCH3

H Cl Cl H H

H – C C – – C C – – C C – – CC – H H Cl ClCl Cl H

2,2,3-trichlorotrichlorobutanebutane

C4H7Cl3

Ranking Halogens

• If more than 1 kind of halogen atom, list them alphabetically.

• Chain is numbered to give lowest number to halogen that comes first in alphabet.

Different Halogens

Chlorine is 1st alphabetically, so it determines numbering.

4 3 2 1

2-chloro-4-fluoro-3-iodobutane

BrCH3CH2CHCHCH3

I

Name:

3-bromo 2-iodo pentane

F ClHCCH F Cl

1,1-dichloro-2,2-difluoroethane

Properties of Halocarbons

• For an alkane & an alkyl halide of similar size & shape, the alkyl halide has the higher boiling point & higher density. Why?

• CH4: bp = -162C & density = 0.423 g/ml

• CH3Cl: bp = -24C & density = 0.911 g/ml

Stronger intermolecular forces.Stronger intermolecular forces.

What intermolecular forces for CCl4?

Boiling Point

(C)

Density

(g/ml)

CH3CH2CH2CH2CH3

pentane

36 0.626

CH3CH2CH2CH2CH2F

1-fluoropentane

63 0.791

CH3CH2CH2CH2CH2Cl

1-chloropentane

108 0.882

CH3CH2CH2CH2CH2Br

1-bromopentane

130 1.218

CH3CH2CH2CH2CH2I

1-iodopentane

155 1.516

Inc Inc

Uses of Alkyl Halides

• Cleaners & solvents

• Teflon & PVC’s are alkyl halides.

• Refrigerants. (used to be chlorofluorocarbons. Now hydrofluorocarbons.)

• Starting materials in many reactions.

Halogen Derivatives

• CH3Cl = local anesthetic

• CHCl3 = solvent, general anesthetic

• CHI3 = antiseptic

• CCl4 = dry cleaning solvent

• CF2Cl2 = refrigerant

• Fluorocarbons = teflon, lubricants, synthetic blood• Chlorofluorocarbons = aerosol propellants,

refrigerants

Table R

• General Formula for halocarbons: R-X

• R represents the entire hydrocarbon part of the molecule. (The alkyl part.)

• X represents the halogen (F, Cl, Br, or I).

Alcohols

• An –OH group replaces a H in a hydrocarbon.

• The –OH group is called the hydroxyl group.

HHCH H

-OH-OH HHCOHOH H

Alcohols are nonnonelectrolytes!

• The hydroxyl group resembles the hydroxide ion of inorganic bases, but it does not form ions in water!

• The hydroxyl group is polar. So alcohols are soluble in water.

Naming AlcohOLOLs

• Based on alkane name.

• Name the parent chain.– Drop the –e and add –OLOL.

• If the parent chain has 3 or more C atoms, number the C’s & give the location of the –OH group.

Naming

H H H HHCCCCH OH H H H

1-Butanolbp = 100C

H H H HHCCCCH H OH H H

2-ButanolBp = 115C

Note: Never more than 1 –OH group per C

More than 1 hydroxyl group

• Prefixes di-, tri-, tetra- used before the –ol ending to tell the # of hydroxyl groups.

• So don’t drop the -e from the alkane name.

• These hydroxyls are on different C atoms!

Classifying Alcohols

• By # of hydroxyl groups

–Monohydroxy: 1 hydroxyl group

–Dihydroxy: 2 “ “

–Trihydroxy: 3 “ “

• By position of each hydroxyl group on main carbon chain.

Monohydroxy Alcohols

• PrimaryPrimary: hydroxyl group attached to end C of chain or branch.

• SecondarySecondary: hydroxyl group attached to C in a chain – C is bonded to 2 other C’s.

• TertiaryTertiary: hydroxyl group attached to C at a branch point – C is bonded to 3 other C’s.

H H H HH-C-C-C-C-O-H H H H H

1-butanolprimary

H H H HH-C-C-C-C-H H H O H H

2-butanolsecondary

H H-C-H H HH-C-C-C-H H O H

H

2-methyl 2-propanolTertiary

H HH-C-C-H O O H H

H H HH-C-C-C-H O O O H H H

Dihydroxy Trihydroxy

Properties of Alcohols

• Contain a H bonded to an O atom.

• Therefore Hydrogen Bonding occursHydrogen Bonding occurs.

• Alcohols have a higher boiling pointhigher boiling point than the corresponding alkane.

• Like dissolves LikeLike dissolves Like. Alcohols tend to be very soluble in water.

OR

H

OR

H-

++

+

-

Which compound has the highest boiling point?

A. CH4

B. C2H6

C. C3H8

D. C3H7OH

Correct response = D.

Table R

• General Formula for Alcohols: ROH.

• R represents the entire hydrocarbon part of the molecule.

OH is the hydroxyl group.

Ethers

• General formula is ROR where R may or may not be the same as R.

• R and R are hydrocarbon branches.

• O is an oxygen bridge.

• Ethers are not linear. They are bent, like water.

Properties of Ethers

• In a purepure ether, no hydrogen bonding – no H bonded to O. Do have weak dipole-dipole interactions – bent, like H2O.

• Dipole-dipole interactions are between dispersion forces & hydrogen bonding.

• Ethyl ether once used as anesthesia

Properties of Ethers

• Compared to alkanes:– Higher boiling pts than similar alkanes.– More soluble in water than alkanes.

• Compared to alcohols:– Lower boiling pts than similar alcohols.– Much less soluble in water than alcohols.

Naming Ethers

• If the 2 hydrocarbon branches are identical, name the branch (once) & add the word ether.

• If the 2 branches are different, list them in alphabetical order followed by the word ether.

H HHCOCH H H

Methyl Ether

H H H H H HHCCCOCCCH H H H H H H

Propyl Ether

H H H HHCOCCCH H H H H

Methylpropyl Ether