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1 2014-1435. Learning Objectives Chapter five discusses the following topics and by the end of this chapter the students will:  Recognize the structure.

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Presentation on theme: "1 2014-1435. Learning Objectives Chapter five discusses the following topics and by the end of this chapter the students will:  Recognize the structure."— Presentation transcript:

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2 Learning Objectives Chapter five discusses the following topics and by the end of this chapter the students will:  Recognize the structure and classes of alkyl halides  Know the common names and understand the IUPAC rules for nomenclature of halo compounds halo compounds  Understand the physical properties of halo compounds (solubility and boiling points)  Know the different methods used in preparation of halo compounds  Know the reactions of halo compounds; nucleophilic substitution, elimination, reduction reactions of Grignard reagents and know the previously disused methods of reducing alkyl halides (Chapter-1)

3 3 Structure Of Alkyl Halides Alkyl halides: are compounds contain the C-X bond where X is a halogen (F,Cl,Br or I) Classes of Alkyl halides:  They are classified according to the type of carbon atom bearing the halogen into:  Primary alkyl halide CH 3 -X and R-CH 2 -X  Secondary alkyl halide (R) 2 -CH-X  Tertiary alkyl halide (R) 3 -C-X

4 145 Chem4 CH 3 -X and R-CH 2 -X : Primary alkyl halide. (R) 2 -CH-X : Secondary alkyl halide. (R) 3 -C-X : Tertiary alkyl halide. Classes and Names of Halogen Compounds According to hydrocarbon gp. 1-Alkyl halides( R-X) has a halogen atom bonded to one sp3 hybrid C atom 2-Allylic halides has a halogen atom bonded to one sp3 hybrid C atom 3-Vinylic halides has a halogen atom bonded to one sp2 hybrid C atom 4-Benzylic halides has a halogen atom bonded to Carbone one away from aromatic ring 5-Aryl halides has a halogen atom bonded directly to an aromatic ring Alkyl Halides

5 Nomenclature OF Alkyl halides derived from the names of parent organic compound (alkane or alkene or alkyne or alcohol or aldehydes and so on) with a prefix indicating halogens and their positions. IUPAC names derived from the names of parent organic compound (alkane or alkene or alkyne or alcohol or aldehydes and so on) with a prefix indicating halogens and their positions. Common names derived from the corresponding alkyl group followed by the name of halogen atom. CH 3 -Cl CH 3 -CH 2 -Br (CH 3 ) 2 -CH-F Common Methyl Chloride Ethyl bromide Isopropyl fluoride IUPAC Chloromethane Bromoethane 2-Fluoropropane Class 1° 1° 2° CommonCyclohexyl Iodide t-Butyl bromide Methylcyclopentyl chloride Common Cyclohexyl Iodide t-Butyl bromide Methylcyclopentyl chloride IUPAC Iodocyclohexane 2-Bromo-2- methylpropane 1-Chloro-1-methyl cyclopentane Class 2° 3 ° 3 °

6 145 Chem6 3-Allyl halides C=C-C- X CH 2 =CHCH 2 Cl Allyl chloride 3-Chloro-1-propene 3-Chlorocyclopentene 4-Benzylic halides:Ar-C-X Benzyl Chloride 2-Vinylic halides Bromocyclohexene C=C-X CH 2 =CHBr Vinyl bromide Bromoethene 5-Aryl halides: Ar-X (X directly attached to  ) Chlorobenzene p-Bromo toluene Notice Alkyl Halides

7 Physical Properties Solubility : All organic halides are insoluble in water and soluble in common organic solvents. Boiling point : The boiling points increases with increasing in molecular weights.  Therefore, the boiling points increases in the order F < Cl < Br < I.  Alkyl halides have higher melting points than alkanes, alkenes, alkynes because of 1. Polarity 2. Molecular weight

8 Preparation Of Halocompounds 1- Direct Halogenation Of Hydrocarbons a)Halogenation of alkanes b) Halogenation of alkenes

9 c) Halogenation of alkynes d) Halogenation of alkyl benzene

10 2- Halogenation Of Alcohols

11 Reactions of Organic Halides 1- Nucleophilic Substitution Reactions

12 2- Elimination Reactions:  Alkyl halides can lose HX molecule to give an alkene. e.g.2  If the haloalkane is unsymmetrical (e.g. 2-bromobutane or 2-bromopentane) a mixture of isomeric alkene products is obtained.

13 3) Formation of Grignard reagent and its reactions Reactions of Grignard reagent

14 4- Reduction of alkyl halides a) Reduction by Zinc metal and acids or by metal hydrides b) Reduction by sodium metal (coupling reaction) c) Reduction using lithium dialkyl cuprate

15 Questions?


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