Ether from alcohols

WILLIAMSON Ether synthesis Synthesis of ethers from alcoholates with alkyl halides... 

Cl3C(/-BuO) C=NH, Bp3-Et20, CH2CI2, cyclohexane, 70-92% yield. This reagent also forms /-butyl ethers from alcohols. 

The first reaction offers a general way of preparing ethers from alcohol. The second reaction is that of esterification, referred to earlier. 

Related Methods Section 123 (Ethers from Alcohols). 

It is now known1 that trialkyl phosphates will indeed alkylate phenols. The idea has been extended2 to the production of methyl ethers from alcohols and trimethyl phosphate, and of a butyl ether according to the equation... 

Under the general term of substitution, we will deal with several transformations in which two molecules of reactants form the product and in which a new C—C or C—O bond or bonds are formed by replacing a C—H bond or another C—O bond. Aldol condensation, esterification, or transesterification and the formation of ethers from alcohols fall into this broad category. We also will include in this section addition to multiple C—C bonds. The published LFERs are summarized in Table III (2, 72-76). 

This method can be extended for the synthesis of allyl alkyl ethers from alcohols with allyl acetate. Thus, the iridium cationic complex [lr(cod)2] BFc, catalyzes the allylation of alcohols 71 with allyl acetate 72 to afford allyl ethers 73 (Equation 10.14) [30]. 

From the protonated hemiacetal the mechanism is similar to that for the formation of ethers from alcohols [Problem 14.7(h)). 

Furthermore, boron trifluoride is used as a catalyst to prepare fluorinated ethers from alcohols and carbon tetrachloride in hydrogen fluoride.19... 

At temperatures above 250°C, the olefin-forming reactions are irreversible but the transformations in the first line of Scheme 3 are reversible. Thus, starting with an arbitrary amine, all other derivatives are obtained by these reactions, called disproportionations, transalkylations or dismutations (the nomenclature is also inconsistent in that the analoguous formation of ethers from alcohols is named dehydration). 

Doyle and co-workers have employed Rh2(pfb)4 as a highly selective catalyst for the room temperature synthesis of silyl ethers from alcohols and triethylsilane.159 The selectivity of the catalyst is demonstrated by reactions of olefinic alcohols, in which hydrosilylation is not competitive with silane alcoholysis when equimolar amounts of silane and alcohol are employed. High yields (>85%) of triethylsilyl ethers are obtained from reactions of alcohols such as benzyl alcohol, 1-octanol, 3-buten-l-ol, cholesterol, and phenol. Tertiary alcohols are not active in this system. 

The formation of ethers from alcohols under acidic conditions (Expts 5.70 and 5.71). 

THE FORMATION OF ETHERS FROM ALCOHOLS UNDER ACIDIC CONDITIONS... 

In the formation of ether from alcohol, H2S04 which is used as catalyst first forms an intermediate compound C2H5HS04. 

Williamson synthesis of phenyl alkyl and dialkyl ethers. Phenols react with alkyl halides in 20% aqueous NaOH containing 1 equiv. of this surfactant at 80° to form phenolic ethers in 85-97% yield. There is no reaction in the absence of CTAB. This procedure is not useful for preparation of dialkyl ethers from alcohols and alkyl halides. Instead, the alkyl chloride, alcohol, a trace of water, and CTAB are heated in THF at 70° with NaOH (2 equiv.). 

Lindley, J. Tetrahedron, (1984), 40, 1433 Related Methods Ethers from Alcohols (Section 123)... 

ACETYLENIC ETHERS FROM ALCOHOLS AND THEIR REDUCTION TO Z-AND E-ENOL ETHERS PREPARATION OF 1-MENTHOXY-1-BUTYNE FROM MENTHOL AND CONVERSION TO (Z)-AND (E)-1-MENTHOXY-1 -BUTENE ([Cyclohexane, 2-(1 -butynyloxy)-4-methyl-1 -(1 -methylethyl)- [1S-(1a,2p,4p)]-], end [[[Cyclohexane, 2-(1-butenyloxy)-4-methyl-1-(1-methylethyl)-, [1S-[1a,2P(Z),4p]]- and [lS-[1 ,2p(E),4P]]-)... 

ACETYLENIC ETHERS FROM ALCOHOLS AND THEIR REDUCTION TO Z- AND E-ENOL ETHERS PREPARATION OF 1-MENTHOXY-1-BUTYNE FROM MENTHOL AND CONVERSION TO (Z)- AND (E)-1 -MENTHOXY-1 -BUTENE... 

Acetylenic Ethers from Alcohols and Their Reduction to Z- and E-Enol Ethers Preparation of 1-Menthoxy-1-butyne from Menthol and Conversion to (Z)- and (E)-1-Menthoxy-1 -butene. 

As an acid chloride, that is, retaining the grouping —CO—CO—, to form the corresponding ethers from alcohols and the oxamides from amines. 

MTO has also been claimed to be the first transition metal complex to catalyze the direct, solvent-independent formation of ethers from alcohols [30]. Aromatic alcohols give better yields than aliphatic ones and reactions between different alcohols have been used to prepare asymmetric ethers. Also catalyzed by 1 is the dehydration of alcohols to form olefins at room temperature. When primary or secondary amines, respectively, are used as the limiting reagents, direct amination of alcohols gives the expected secondary or tertiary amines in yields of ca. 95 %. Disproportionation of alcohols to carbonyl compounds and alkanes is also observed for aromatic alcohols in the presence of MTO as catalyst. 

Benedict, D. R., Bianchi, T. A., Cate, L. A. Synthesis of simple unsymmetrical ethers from alcohols and alkyl halides or sulfates the potassium hydroxide/dimethyl sulfoxide system. Synthesis 1979,428-429. 

Rao, H. S. P., Senthilkumar, S. P. A convenient procedure for the synthesis of allyl and benzyl ethers from alcohols and phenols. Proc. -indian Acad. Sci., Chem. Sci. 2001,113,191-196. 

The Mitsunobu reaction proved to be useful for the synthesis of aryl alkyl ethers from alcohols and phenols. The method proceeds under mild conditions and tolerates many functional groups with inversion of configuration, as exemplified by the reactions of lactate and ewrfo-5-norbornen-2-ol (equations 4 and Neighboring group participation,... 

Formation of an anhydride from an acid is similar to the formation of an ether from alcohols. When dicarboxylic acids are heated up to 200 - 300 °C, cyclic anhydrides with five or six carbons are formed. 

Different amides and anilines have been selectively mono-N-alkylated using catalytic heterogeneous palladium and carbonyl compounds as alkylating agents. The same method has been applied to the synthesis of ethers from alcohols. Reaction parameters have been studied in details and a mechanism is proposed. 

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