Halogenated Alkanes

BLANK are the derivatives of alkanes in which hydrogen atom is replaced by a halogen atom F, Cl, Br, or I

Represented by R-X-R-alkyl group, X-halogen like chloro, Fluoro, Bromo, and Iodo group

compounds with a halogen atom bonded to a saturated, sp3- hybridized carbon atom.

halide is attached to a methyl group.

carbon to which halogen is bonded is attached to only one other carbon.

carbon to which halogen is bonded is attached to two other carbons.

carbon to which halogen is bonded is attached to three other carbon.

Classifications of Alkyl Halides

Only one additional alkyl group is bonded to the carbon that bears the halogen atom. ONE CARBON ATOM

the halogenated carbon is connected straight to two more alkyl groups, which might be the same or different TWO CARBONS CONNECTED

Three alkyl groups, which may be the same or different, are immediately linked to the carbon atom carrying the halogens THREE CARBONS CONNECTED

Two general trends relative to boiling points and melting points of halogenated hydrocarbons containing a single halogen atom are:

Boiling points and melting points increase as the size of the alkyl group present increases. (This is due to increasing intermolecular forces associated with increased molecular surface area)

Boiling points and melting points increase as the size of the halogen atom increases from fl uorine (F) to iodine (I).

PRIMARY Alkyl halides are slightly soluble in water, but more soluble in organic solvents.

As the amount of alkyl group increases, the acidity decreases

The bond strength of C–X decreases as the size of X increases => iodine is a better leaving group than fluorine

the alkyl halides are highly reactive, the order of reactivity is:

The high reactivity of alkyl halides can be explained in terms of the nature of C X bond which is a HIGHLY POLARIZED COVALENT BOND due to the large difference in the electronegativities of carbon and halogen atoms.

Halogens are more electronegative than carbon atoms. Therefore, the electron density along the C–X bond is shifted towards X the C–X bond is polar. Alkyl halides exhibit dipole-dipole interactions due to the polar C-X bond

ALKYL HALIDES OF PHARMACEUTICAL IMPORTANCE

used for dry cleaning, spot removing

used to dissolve the caffeine from coffee beans to produce decaffeinated coffee

Solvents 2 types

starting materials for making complex molecules

for example, the conversion of alkyl halides to organometallic reagents (compounds containing carbon metal bonds) is important tool for organic synthesis

One major use of BLANK has been as propellants in aerosol inhalers for drugs used to treat asthma

BLANK used originally as general anesthetic but it is toxic and carcinogenic.

is a mixed halide sold as Halothane®

are used as refrigerants and foaming agents.

Freons can harm the ozone layer so they have been replaced by

Pesticides such as BLANK are extremely toxic to insects but not as toxic to mammals.

can not be destroyed by bacteria so they accumulate in the soil to a level which can be toxic to mammals, especially, humans.

Colorless, extremely flammable gas with a mildly sweet odor

present in volcanic gases; produced by algae and giant kelp; used as an industrial solvent; once used widely as a refrigerant; no longer found in consumer products because of toxicity concerns

Colorless, volatile liquid with a mildly sweet odor

chemical intermediate in production of silicone polymers; used as a paint stripper and degreaser; once used to decaffeinate coffee but has been replaced by liquid carbon dioxide due to concern about trace amounts of BLANK remaining in the coffee