- Functional Groups - Halogens, Alcohols & Ethers.

- Functional Groups- Halogens, Alcohols & Ethers

Functional GroupsBesides hydrogen or carbon bonded to carbonMany other atoms can bond to carbon and theseLead to the formation of what are called “Functional groups”

Each Functional group has it’s own unique chemicalAnd physical properties

So what kind of functional groups are there?

Check out Table R in your Reference Table.

TABLE R – Functional Groups-Halides-Alcohols-Ethers

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.

Properties of Alkyl Halides

Alkyl halides are extremely unreactive

Often used when chemical inertness is important-Examples: CFC’s (refrigerants, Aerosol propellants, Teflon (polymer), Brominated compounds (Fire retardant clothing)-many of these compounds are now banned from use for health and environmental reasons.

Properties of Alkyl Halides Alkyl halides due to there high molecular wt. have considerably higher B.P. than their corresponding alkanes

Bonds are polar but compounds are not soluble in water Probably because they can’t form H bonds

Is CHCl3 a polar compound?

What about CCl4?

Yes

No

Propane Chloropropane Bromopropane

B.P. (deg. C) -42 47 71

Density (g/ml) (Gas) .890 1.335

Naming Organic HalidesUse prefixes to specify substituent:

– fluoro, chloro, bromo, iodo

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

• If necessary, give locations by numbering C-atoms in backbone so that the halide has the lowest number.

c-c-c-c-c Br Br

2,3-dibromopentane

Naming Halides

CH3Cl CH3CHFCH3

HH–C–Cl H

Chloromethane

H H HH–C–C–C–H H F H

C3H7F

2-fluoropropane

“Chloroform”

Name the following Compound:

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

Name this compound:

3-Bromo-2-Iodopentane

Name this compound:

F ClH-C C-H F Cl

1,1-dicloro-2,2-difluoroethane

One of the “freons”

Alcohols

• Alcohols contain the polar -OH functional group– OH groups are capable of Hydrogen bonding

• This polar functional group affects physical properties– B.P is much higher than the corresponding Alkane

• Ethanol (C2H5OH) +78C // Ethane (C2H6) -89C

– Low Mol. Wt. Alcohols are very soluble in water

Hydroxyl groups

Alcohols can hydrogen bond because they have aHydrogen atom that is bonded to oxygen.

CH3–CH2–O-H

CH3–CH2–O-H

This results inMuch higher B.P.’sAnd higher watersolubulity

H-O-H

Physical properties of Alcohols

Name Formula B.P. (C) Sol.

(g/100g H20)

Methanol CH3OH 64.5 Fully miscible

Ethanol CH3CH2OH 78.3 Fully miscible

Propanol CH3(CH2)2OH 97 Fully miscible

Butanol CH3(CH2)3OH 118 7.9

Naming Alcohols

• Select as the parent structure the longest continuouscarbon chain that contains the –OH

• Drop the –e from the alkane name of the carbon chain and add –ol

• Indicate by a number (if necessary) the position of the –OH group

ethanol 2-propanol

Types of Alcohols

Alcohols are also considered to be either- primary, secondary, or tertiary alcohols

Designations correspond to which carbon atom the –OH group is bonded to

- Affects Chemical Reactivity/Properties- Tertiary more reactive than Primary

Primary alcohol: OH bonded to –CH20HSecondary alcohol: OH bonded to –CHOHTertiary alcohol: OH bonded to -COH

Types of Alcohols

Primary alcohol

Secondary Alcohol

Tertiary Alcohol

Ethers

Even though ethers have an oxygen atom in their

Structure they are unable to form hydrgen bonds with themselves

- alkyl groups are bonded directly to Oxygen

- No hydrogen bonded to Oxygen

Ethers are not linear; They have a bent shape similar to water

Ether’s Properties BP’s tend to be low

Comparable to similar MW hydrocarbonsNo internal H-bonding

Solubility in water is reasonably high for lower M.W. ethers

H-Bonding to Water is possible

Propane Dimethylether Diethylether

M.W. 44 46 74

B.P. (deg. C) -42 -24 35

Sol in Water

(g/ml)

Na Na 8

Naming Ethers(common names)

• Name the groups (alkyl) on either side and add ether to the end.

• List attached alkyl groups in order of increasing size• If they are the same the side chain is labeled “Di”

• NO NUMBERS NEEDED to designate location of Oxygen!

Naming Ethers

Name this compound:

Name this compound:

Dimethyl ether

Ethylpropyl ether