Halogenated

HALOGENATED [pic 1]

Halogenated - it hydrocarbon derivatives, wherein one or more hydrogen atoms are replaced by halogen atoms. Halogenated depending on the nature and character of halogen hydrocarbon radical divided into:

[pic 2]

Nomenclature

Halides can be called prefixed halogen (bromine, chlorine, etc.) to the name of the parent structure. The chain is numbered so that the halogen received the lowest number. If the same amount of the halogen is added - di-, tri-, tetra-.

СН3 С1 — methyl chloride or chloromethane

СН3-СН2-С1 - ethyl chloride (chloroethane)

СН3-СН2-СН2С1 - propyl chloride (1 chloropropane)

СН3-СН-СН3 - 2 chloropropane or isopropyl chloride

[pic 3]

С1

Methods for obtaining

1. Radical substitution of alkanes:

СН3 - СН3 + С12(Ьν) → СН3 - СН2С1 + НС1

2. From alkenes:

СН3СН = СН2 + НВг(Н202)    → СН3 - СН2 - СН2Вг

3. Of the alcohols:

СН3 СН2ОН → СН3СН2Вг + КНSО4 + Н20

4. From aldehydes and ketones:

[pic 4]R – C = O                         С1

[pic 5]        + Р С13 → R – C – Н + РОС1 + НС1

Н                         С1

          С1

R – C – R + Р С13 → R – C – R1

 [pic 6][pic 7]                           С1

 O

5. Among the salts of carboxylic acids:

R – CООNa + Br2 → R – Br + CO2 + NaBr

Chemical properties

Reactivity of halogen determined by the nature of communication R-HA1 and the structure of the molecule. Nature halogen determines the polarity and polarizability of the bond strength of R-HA1. Halogenated compounds from all organic compounds - the most active. Their activity due to the fact that communication with → HA1 strongly polarized. The polarization of one bond leads to the electron density distribution over the entire molecule (inductive effect). The most active iodinated derivative.

If we compare the activity of the character radical, the haloaryl (aromatic) less active than the R-HA1 haloalkanes.

СН3СН2С1 >> СН2=СН-С1 >> [pic 8]- С1

[pic 9]

activity increases

1) SN type - halo associated with carbon can be easily replaced in the form of a halogen ion to another more powerful, rich electrons - nucleophilic reagent

R : На1 + :Nu - → R : Nu + : На1

СН3С1 + HOH                СН3OH + HCl

               + NaOH                  СН3OH + NaCl[pic 10][pic 11]

              + NaCN                 СН3CN+ NaCl[pic 12][pic 13][pic 14]

              +NaNO2                 СН3NO2 + NaCl[pic 15]

        +NaNH2         СН3NH2 + NaCl

        +CH3ONa          CH3OCH3 + NaCl[pic 16][pic 17]

        +CH3COONa         CH3COOCH3 + NaCl[pic 18]

        + NaSH          CH3SH + NaCl

[pic 19]

Mechanism SN

SN mechanism studied in great detail by Ingold and Hughes. It has been established that they pass through two different mechanisms. For primary haloalkanes characteristic reaction SN2 - bimolecular substitution for tertiary - SN1 - monomolecular substitution for possible secondary SN1 and SN2.

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