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ETHER

King Saud University Chemistry Department. ETHER. King Saud University Chemistry Department. Structure and nomenclature of ethers Ethers are compounds of formula R -0-R ', where R and R' may be alkyl groups or aryl (benzene ring) groups. Common names (Alkyl Alkyl Ether Names)

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ETHER

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  1. King Saud University Chemistry Department ETHER 145 Chem

  2. King Saud University Chemistry Department Structure and nomenclature of ethers Ethers are compounds of formula R -0-R', where R and R' may be alkyl groups or aryl (benzene ring) groups. Common names (Alkyl Alkyl Ether Names) Common names of ethers are formed by naming the two alkyl groups on oxygen and adding the word ether. Under the current system, the alkyl groups should be named in alphabetical order. 145 Chem

  3. IUPAC Nomenclature King Saud University Chemistry Department • Ethers are named as “Alkoxy alkanes”, where the longer chain alkyl group is the alkane and thus is written at the end. Names of some common alkoxy groups (RO-): CH3O-- Methoxy CH3CH2CH2O-- n-Propoxy CH2CH3O-- Ethoxy (CH3)2CHO-- Isopropoxy

  4. King Saud University Chemistry Department The common alkoxy substituents are given names derived from their alkyl component

  5. King Saud University Chemistry Department Examples 145 Chem

  6. King Saud University Chemistry Department Examples Common: Methyl Phenyl ether (anisole) IUPAC : Methoxy benzene Common: Diphenyl ether IUPAC : Phenoxy benzene 3-Methoxyhexane 5-Ethoxy-2-heptene propenyloxy benzene 145 Chem

  7. Physical Properties of Ether King Saud University Chemistry Department • Boiling Points • The boiling points of ethers are lower than those of alcoholshaving the same molecular weights. • Solubility in water • Ethers are much less soluble in water than alcohols. • More water-soluble than hydrocarbons of similar molecular weight. 145 Chem

  8. King Saud University Chemistry Department Preparation of ehers Ethers by dehydration of alcohols The dehydration of alcohols takes place in the presence of acid catalysts (H2SO4, H3PO4) under controlled temperature. The general reaction for ether formation is: Examples 145 Chem

  9. King Saud University Chemistry Department The Williamson synthesis of ethers 145 Chem

  10. King Saud University Chemistry Department The alkoxide is commonly made by adding Na or K to the alcohol Examples 3,3-dimethyl-2-pentanol 2-ethoxy-3,3-dimethypentane 145 Chem

  11. King Saud University Chemistry Department Reaction of Ether Cleavage of ethers by hot concentrated acids When ethers are heated in concentrated acid solutions, the ether linkage is broken General equation: Specific example The acids most often used in this reaction are HI, HBr, and HCl. 145 Chem

  12. King Saud University Chemistry Department • If an excess of acid is present, the alcohol initially produced • is converted into an alkyl halide by the reaction. For example 145 Chem

  13. King Saud University Chemistry Department Cyclic Ethers Epoxide Epoxides are cyclic ethers in which the ether oxygen is part of a three-membered ring. • The simplest and most important epoxide is ethylene oxide. 145 Chem

  14. King Saud University Chemistry Department Peroxyacid Epoxidation Peroxyacids (sometimes called peracids) are used to convert alkenes to epoxides. If the reaction takes place in aqueous acid, the epoxide opens to a glycol. Because of its desirable solubility properties, meta-chloroperoxybenzoic acid (MCPBA) is often used for these epoxidations. 145 Chem

  15. King Saud University Chemistry Department Example 145 Chem

  16. King Saud University Chemistry Department • Their reactivity is due to the strain in the three-membered ring, which is relieved when the epoxide ring is opened after a reaction has taken place. • Examples of ring-opening reactions of ethylene oxide that form commercially important products are: • 1- Epoxides open in acidic solutions to form glycols. 145 Chem

  17. King Saud University Chemistry Department 2- Epoxides open in acidic alcohol solutions to form 2-alkoxy alcohols. 3- When an epoxide reacts with a hydrohalic acid ( HCl,HBr, or HI), a halide ion attacks the protonated epoxide. 4- Reactions of Epoxides with Grignard and Organolithium Reagents 145 Chem

  18. King Saud University Chemistry Department Exercise 1 Give a correct name for each of the following compounds. Exercise 2 Propose a Williamson synthesis of 3-butoxy-1,1-dimethylcyclohexane from 3,3-dimethylcyclohexanol and butanol. 145 Chem

  19. King Saud University Chemistry Department Exercise 3 Predict the products of the following reactions. 145 Chem

  20. King Saud University Chemistry Department Thank you for your attention 145 Chem

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