Addition Reaction.pptx

Addition reaction of organic compounds in organic chemistry
Electrophilic addition reaction
Nucleophilic addition reaction
Markonikov's addition
Ozonolysis
Polar addition reactions
Non polar addition reactions
Cycloaddition reactions
Free radical addition
Diels elder reaction

Addition to alkynes
Factors associated with alkenes

1. Addition Reaction Represented By:Group 6 Saira-028,Maham,Kinza,Hafifa,Nida,Arooj-066 Represnted To: Ms . Uswa

2. Table of Content Introduction Types of Addition Reaction Electrophilic Addition Reaction(Mechanism) Nucleophilic Addition Reaction(Mechanism ) Markovnikov Rule Ozonolysis of Alkenes(Mechanism) Factors Associated with Alkenes Reaction of Alkynes

3. INTRODUCTION Reactions which involve the combination of two reacting molecules to give single molecule of product. A+B C (product) These are limited to chemical compounds with multiple bonds.

4. Alkenes mostly take part in addition reactions. The π -bond is broken and two new σ -bonds are formed. Alkenes are electron rich, with elctron density of π -bond concentrated above and below.

5. Addition reactions to alkenes and alkynes are sometimes called saturation reactions. Addition reactions are the reverse of elimination reactions.

6. TYPES OF ADDITION REACTION

7. POLAR ADDITION REACTIONS Electrophile Addition The process of adding an electrophile to the pi bond of an alkene. An electrophile forms a sigma bond with a vinyl carbon atom in double bond. Nucleophile Addition The process of adding a nucleophile to either an electron-deficient species or pi bond in a molecule. A nucleophile forms a sigma bond with a carbon atom in the substrate.

8. Example of Electrophilic Example of Nucleophilic

9. NON POLAR ADDITION REACTION Free Radical Addition The addition reaction which involves free radical. The reaction occurs between a radical and a non-radical. It may involve two radicals. It is also known as radical chain mechanism. Cyclo Addition The reaction in which two or more unsaturated molecules combine. It forms a cyclic adduct(cyclization). There is net reduction of bond multiplicity. It permits carbon-carbon without nucleophile or electrophile.

10. Example of Free Radical Addition Chlorination of Methane A reaction between methane and chlorine in the prsence of UV light. A product of chloromethane is produced. CH ₄ + Cl ₂ → CH ₃ Cl+HCl Mechanism 1.Chain initiation: Cl 2   →   2Cl· 2.Chain propagation reactions   : CH 4  + Cl ·→CH· 3 + HCl CH· 3  + Cl 2 → CH 3 Cl + Cl · 3.Chain termination reactions: 2Cl·→ Cl 2 CH· 3  + Cl ·   →  CH 3 C l

11. Example of Cyclo addition Diels-Alder reaction A reaction between a conjugated diene and a substituted alkene( dienophile ). A substituted cyclohexene derivative is formed.

12. Electrophilic Addition The addition of an electrophile to a pi bond of an alkene. The carbon-carbon in an alkene is a region of high electron density. This makes the C=C bond attractive to electrophiles. This is an electrophile addition reaction. .

13. Mechanism It is a two step mechanism , Step 1: H-Br undergoes hetrolytic bond fission. The proton (H+) bonds with the caarbon atom of the C=C. A carbocation intermediate is formed.

14. Step 2: The anion uses a lone pair of electrons to form a bond with the carbocation. The bromide ion forms a bond with the carbocation producing bromoethane .

15. Nucleopilic Addition Reaction A nucleophile forms a single bond with an electron defficient species. The conversion of carbonyl groups into variety of functional groups.

16. Mechanism The electrophilic carbonyl carbon forms a sigma bond with the nucleophile. The carbon-oxygen pi bond is broken, forming an alkoxide intermediate. The subsequent protonation of the alkoxide yields the alcohol derivative. Generally, these reactions are broken down into three steps:

17. Addition of HCN Aldehydes and ketones undergo reaction with HCN to produce cyanohydrins . The reaction progresses very slowly by using pure hydrogen cyanide. The catalyst helps to speed up the reaction. As catalysis helps in the generation of cyanide ion (CN) which acts as a stronger nucleophile.

18. MECHANISM The polar nature of the C=O bond makes the carbonyl carbon electrophilic in nature. The CN¯ executes a nucleophilic attack on the carbonyl carbon, resulting in the formation of an intermediate . This intermediate is now protonated to afford the cyanohydrin product.

19. MARKOVNIKOV RULE Hydrogen is added to the carbon with the most hydrogens and the halide is added to the carbon with least hydrogens.  the addition of hydrobromic acid (HBr) to propene; The majority of the products formed obey Markovnikov’s rule, whereas the minority of the products do not.

20. Step 1: The alkene is protonated and it gives rise to the more stable carbocation as   T wo types of carbocations that can be formed  by protonation, Primary Secondary(more stable and preferred)

21. Step 2: The halide ion nucleophile now attacks the carbocation.  The reaction yields the alkyl halide.   Rule was developed for its application in the addition reaction of hydrogen halides to alkenes . The opposite to this is anti- Markovnikov rule.

22. Ozonolysis of Alkene Ozonolysis implies that ozone causes the alkene to break. a method of oxidatively cleaving alkenes using ozone (O3), a reactive allotrope of oxygen. The process allows for carbon-carbon double or triple bonds to be replaced by double bonds with oxygen.

23. Mechanism of Ozonolysis Step 1: The π electrons act as the nucleophile, attacking the ozone at the electrophilic terminal O. A second  C-O  is formed by the nucleophilic O attacking the other end of the  C=C .

24. Step 2: The cyclic species called the malozonide rearranges to the ozonide . Step 3: The ozonide decomposes on  work-up. Reductive work-up with (usually Zn / acetic acid) gives the two carbonyl groups.

25. ADDITION REACTIONS OF ALKYNES  The principal reaction of the alkynes is addition across the triple bond to form alkanes . These addition reactions are analogous to those of the alkenes . HYDROGENTION HALOGENATION HYDROHALOGENATION HYDRATION

26. Hydrogenation Alkynes undergo catalytic hydrogenation with the some catalyst( Pt , Pd , Lindlar’s catalyst) . In a stepwise manner an alkenes is formed first and then alkane. Halogenation The addition of halogens to an alkyne proceeds in the stepwise manner. the formation of alkene , which undergoes further reaction to a tetrahaloalkane .

27. Hydrohalogenation   Hydrogen halides react with alkynes in the same manner as they do with alkenes . Both steps in the above addition follow the Markovnikov rule. Hydration The addition of the elements of water across the triple bond of an alkyne leads to the formation of aldehydes and ketones . t erminal alkyne aldehyde non-terminal alkyne ketone

28. REFERENCES Morrison , R. T.; Boyd, R. N. (1983). Organic Chemistry(4th  ed.). Boston: Allyn and Bacon. March , Jerry; (1985). Advanced Organic Chemistry reactions, mechanisms and structure (3rd ed.). New York: John Wiley & Sons. Fleming, Ian (2010). Molecular orbitals and organic chemical reactions. New York: Wiley .   Myles W. Smith; Phil S. Baran (2015-08-28). "As simple as [2+2]".  Science 349  (6251): 925–926. Hein, Sara M. (June 2006). "An Exploration of a Photochemical Pericyclic Reaction Using NMR Data". Journal of Chemical Education.  83  (6): 940–942.

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