Properties of haloalknaes:

Physical Properties:

Haloalkanes generally resemble the parent alkanes in being colorless, relatively odorless, and hydrophobic.

Their boiling points are higher than the corresponding alkanes and scale with the atomic weight and number of halides. The boiling points of alkyl chlorides, bromides and iodides follow the order RI > RBr > RCl where R is an alkyl group.

Increased strength of the intermolecular forces—from London dispersion to dipole-dipole interaction because of the increased polarity.

Carbon tetraiodide (CI₄) is a solid whereas carbon tetrafluoride (CF₄) is a gas.

Haloalkanes are better solvents than the corresponding alkanes because of their increased polarity.

Many are alkylating agents, with primary haloalkanes and those containing heavier halogens being the most active (fluoroalkanes do not act as alkylating agents under normal conditions).

Haloalkanes are not able to form hydrogen bonds with water and, even though they are polar in nature, they are practically insoluble in water.

Chloroalkanes are lighter than water while bromides and alkyl iodides are heavier. fluoride > chloride > bromide > iodide.

Chemical properties of haloalkanes:

Bond strength: C—F > C—Cl > C—Br > C—I

bond	strength (kJ mol-1)
C-F	484
C-Cl	338
C-Br	276
C-I	238

The orbitals C uses to make bonds are 2s and 2p. The overlap integral is larger the closer the principal quantum number of the orbitals is, so the overlap is larger in the bonds to lighter halogens, making the bond formation energetically favorable.

Bond reactivity: C—F < C—Cl < C—Br < C—I

Stronger bonds are more difficult to break, making them less reactive. In addition, the reactivity can also be determined by the stability of the corresponding anion formed in solution. One of the many trends on the periodic table states that the largest atoms are located on the bottom right corner, implying that iodine is the largest and fluorine being the smallest. When fluorine leaves as fluoride (if it does) in the reaction, it is not so stable compared to iodide. Because there are no resonance forms and inductive stabilizing effects on these individual atoms, the atoms must utilize their own inherent abilities to stabilize themselves. Iodide has the greatest surface area out of these four elements, which gives it the ability to better distribute its negative charge that it has obtained. Fluorine, having the least surface area, is much more difficult to stabilize. This is the reason why iodine is the best leaving group out of the four halogens discussed.

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

Iodide > Bromide > Chloride (Nature of the halogen atom)

Tertiary > Secondary > Primary (Type of the halogen atom)

Amongst the primary alkyl halide, the order of reactivity is : CH₃X > C₂H₅X > C₃H₇X, etc.