Important Name reaction

Name reactions:Clemmensen reduction, Darzens condensation, Diels Alder, Eschweiler-Clarke, Friedel-Crafts, Grinard, HofmanMannich, Michael, Meerwin- Pondorf- Verley, Perkin, Reformatsky, Reimer-Tiemann,, Witting and Wolf-Kishner reduction, Aldol condensation.

1. A Presentation on “Name Reactions” Jashore University of Science and Technology Shohan Hossain B. pharm; JUST Session : 2018-2019

2. Clemmensen reduction: Clemmensen reduction is a chemical reaction described as a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and hydrochloric acid. This reaction is named after Erik Christian Clemmensen , a Danish chemist. Example:

3. Mechanism: There are two popular proposals of mechanism The " Carbanionic mechanism ", where the zinc attacks the protonated carbonyl directly, and the " Carbenoid mechanism ", which is a radical process and the reduction happens on the surface of the zinc metal.

4. Application: Widely used to convert a carbonyl group into a methylene group Preparation of polycyclic aromatics To reduce aliphatic and mixed aliphatic-aromatic carbonyl compound

5. Darzens reaction The Darzens reaction is the chemical reaction of a ketone or aldehyde with an α- haloester in the presence of a base to form an α,β-epoxy ester. Darzens reaction also known as the Darzens condensation or glycidic ester condensation Example:

6. Appliation : Used in rearrangement of alkenyl epoxide- dihydrofuran Preparation of vinyl epoxide Used in synthesize of several calcium channel blockers Used in conversion of glycidic ester

7. Diels–Alder reaction The Diels–Alder reaction is an organic chemical reaction (specifically, a [4+2] cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene derivative

8. Mechanism: Diels-Alder reaction can also be depicted in the following manner in which the curved arrows are used to show that two new σ-bonds are formed, three π-bonds are broken, and one new π-bond is formed-

9. Application: Used to generate molecular complexity efficiently synthesis of pharmacologically active ingredients synthesis of agrochemicals, and flavors and fragrances used in research and development perspective

10. Eschweiler–Clarke reaction The Eschweiler–Clarke reaction is a chemical reaction whereby a primary (or secondary) amine is methylated using excess formic acid and formaldehyde. It is also called the Eschweiler–Clarke methylation.

11. Mechanism:

12. Application: synthesis of pharmacologically active ingredients Used in conversion of aromatic compound Development of pharmaceutical active molecule

13. Friedel crafts The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877 to attach substituents to an aromatic ring. Friedel–Crafts reactions are of two main types: alkylation reactions and acylation reactions . Both proceed by electrophilic aromatic substitution.

14. Friedel–Crafts acylation Friedel–Crafts acylation involves the acylation of aromatic rings. Friedel–Crafts acylation is also possible with acid anhydrides.

15. Friedel-Crafts Alkylation Friedel–Crafts alkylation involves the alkylation of an aromatic ring with an alkyl halide using a strong Lewis acid catalyst. With anhydrous ferric chloride as a catalyst, the alkyl group attaches at the former site of the chloride ion

16. Application: Used in construction of a dibenzosilole skeleton Used in synthesis of pharmaceutical active agents Used in some organic compound conversion Used in chemical industries

17. Grignard reaction The Grignard reaction is an organometallic chemical reaction in which alkyl, vinyl, or aryl-magnesium halides add to a carbonyl group in an aldehyde or ketone

18. Mechanism of Grignard reaction: The Grignard reagent functions as a nucleophile, attacking the electrophilic carbon atom that is present within the polar bond of a carbonyl group. The addition of the Grignard reagent to the carbonyl typically proceeds through a six-membered ring transition state

19. Application: Synthesis of hydrocarbon Synthesis of alcohols Used in industrial production, e.g.- Tamoxifen

20. Hofman-Mannich reaction The Mannich reaction is an organic reaction which consists of an amino alkylation of an acidic proton placed next to a carbonyl functional group by formaldehyde and a primary or secondary amine or ammonia. The Mannich reaction is also considered a condensation reaction. Example:

21. Mechanism: Step 1: The mechanism of the Mannich reaction starts with the formation of an iminium ion from the amine and the formaldehyde

22. Step 2: The compound with the carbonyl functional group (in this case a ketone) can tautomerize to the enol form, after which it can attack the iminium ion.

23. Application: Synthesis of alkyl amines & peptides Synthesis of nucleotides & antibiotics Used in soap and detergent preparation Used in drugs such as Tetracyclin , Tramadol, Tolmetin

24. Michael reaction The Michael reaction or Michael addition is the nucleophilic addition of a carbanion or another nucleophile to an α,β-unsaturated carbonyl compound

25. Mechanism : 1. In the first step, enolate is produced in the presence of a base by taking the α-hydrogen of the carbonyl containing compound. 2. Enolate reacts with the michael acceptor to form the new compound with carbon-carbon bond. 3. Finally, the base got regenerated forming the final product.

26. Application: Widely used in all kinds of natural products and drugs Synthesis of complex compound with biological activities Widely used in chemistry lab

27. Perkin reaction The Perkin reaction is an organic reaction used to convert an aromatic aldehyde and an anhydride to an α - β unsaturated carboxylic acid using sodium acetate, a base & an acid workup

28. Application: Used in cinnamic acid preparation Used in laboratory synthesis

29. ALDOL CONDENSATION REACTION # Condensation between two molecules of an Aldehyde to form a beta- hydroxy aldehyde is known as a ALDOL CONDENSATION . # ALDOL CONDENSATION is possible only when the carbonyl compound contains at least one alpha-hydrogen atom.

30. This is the example of ALDOL CONDENSATION reaction of acetaldehyde containing alpha-hydrogen. The following Aldehydes or ketones having no alpha-hydrogen atom do not undergo ALDOL CONDENSATION

31. MECHANISM OF reaction STEP 1: First, an acid-base reaction. Hydroxide functions as a base and removes the acidic alpha-hydrogen giving the reactive enolate . STEP 2: The nucleophilic enolate attacks the aldehyde at the electrophilic carbonyl C in a nucleophilic addition type process giving an intermediate alkoxide . STEP 3: An acid base reaction. The alkoxide deprotonates a water molecule creating hydroxide and the beta- hydroxyaldehyde or aldol product .

32. An enolate ion is formed as an anion when an alpha-hydrogen in the molecule of an aldehyde or a ketone is removed as a hydrogen ion.

33. The alkoxide ion is the conjugated base of alcohol

34. Alkoxide ion is protonated by water .

35. Applications of aldol condensation reaction: # In gluconeogenesis and photosynthesis the reaction leads to c-c bond, which is considered as important reaction in biochemistry of metabolism. # It works as an intermediate for the production of perfumes . # It is also used in pharmaceutical manufacturing like, a,b unsaturated ketones and aromatic ketones known as chalcones . # This reaction is also used to create plasticizers.

36. Wolf- kishner reduction recation # The WOLF-KISHNER reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene group. # The conversion of C=O groups into CH2 groups by heating their hydrozones , semicarbazones , or azines in the presence of sodium hydroxide.

37. MECHANISM OF ACTION STEP 1- Deprotonation : A second deprotonation yields a new anion. STEP 2- Dissociation: A carbanion dissociates as a high energy leaving group and the loss of nitrogen gas moves the process forward. STEP 3- Protonation: The carbanion rapidly removes a proton from water to yield the reduced product

38. Application of wolff-kishner reaction # The reaction has very board application in organic synthesis , specially for the multiwalled carbon nanotubes . # This reaction is also used in the decarbonylation of tricyclic allylic acetate containing ketone. # This reaction has also been used on kilogram scale for the synthesis of a functionalized imidazole substrate.

39. Wittig reaction # The WITTIG REACTION or WITTIG OLEFINATION is a chemical reaction that involves the conversion of aldehyde and ketones to alkenes with the help of phosphorous yields. # example ,

40. Mechanism of action Step-1 : The negative carbon of the yield attaches with carbonyl carbon to form betaine , a molecule with non-adjacent opposite charges.

41. Mechanism of action Step-2 : Betaine undergoes elimination of triphenyl phosphine oxide to give alkene.

42. application # This reaction is used in the preparation of alkene from aldehydes and ketone like, production of methyl propene from the reaction of acetone and yield . # The Wittig reaction is used to produce pure alkene of known structure and they are used for mono, di, trisubstituted alkenes .

43. Riemer-tiemann reaction # The RIEMER-TIEMANN reaction is a chemical reaction used for the ortho-formylation of phenols. # The simplest example being the conversion of phenol to salicyldahyde .

44. Mechanism of reaction # Chloroform (1) is deprotonated by strong base (normally hydroxide) to form the chloroform carbanion (2) which will quickly alpha-eliminate to give dichlorocarbene (3). # This is the principle reactive species. The hydroxide will also deprotonate the phenol (4) to give a negatively charged phenolate (5). The negative charge is delocalized into the aromatic ring (6) , making it far more nucleophilic and increase its ortho selectivity. # Nucleophilic attack of the dichlorocarbene from the ortho position gives an intermediate dichloromethyl substituted phenol (7) . After basic hydrolysis , the desired product (9) is found.

45. application # This reaction is used to produce salicylaldehyde , this compound is used as chelating agent , and in the detection of ketonuria in human body. # This reaction is also used to produce some flavoring agent like vanilline for the taste of vanilla.