And ether formation

Trifluoromethanesulfonic acid is miscible in all proportions with water and is soluble in many polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and acetonitrile. In addition, it is soluble in alcohols, ketones, ethers, and esters, but these generally are not suitably inert solvents. The acid reacts with ethyl ether to give a colorless, Hquid oxonium complex, which on further heating gives the ethyl ester and ethylene. Reaction with ethanol gives the ester, but in addition dehydration and ether formation occurs. 

The piincipal by-pioducts aie the result of direct chlorine addition to give 1,2-dichlotoptopane [78-87-5] and ether formation. The ether product is dichloropropyl ether [108-60-1] or 2,2 -oxybis(l-chloropropane). 

However, the investigations of the mechanism of olefin and ether formation from alcohol (Sect. 2.2) revealed the importance of basic sites. It is feasible that, for esterification also, pairs of acidic and basic sites might be necessary. 

The Degussa process (now owned by Dupont) starts from acrolein, which is hydrated in the presence of an acidic ion exchanger into 3-hydroxypropanal (3HP, Fig. 8.8 a). The latter is subsequently extracted into isobutyl alcohol and hydrogenated over a Ni catalyst [53]. The overall yield does not exceed 85%, due to competing water addition at the 2-position and ether formation in the initial step. It has been announced that Degussa will supply up 10 kt a-1 to Dupont until the fermentative process of the latter company (see below) comes on stream [54]. 

Fletcher JW, Seddon WA. (1975) Alkali metal species in liquid amines, ammonia and ethers. Formation by pulse radiolysis. J Phys Chem 79 3055-3064. 

The norbomadiene derivatives (157) undergo efficient ring closure to give the corresponding quadricyclanes (158). The ester functions of these products were elaborated by reduction and ether formation to provide a path to so-called tentacle molecules. 

Phosphates are also active dehydration catalysts [6,8,9]. Although a mixed (El and E2) mechanism has been reported [24], most of these materials and particularly BPO4 have typical El behavior [25-27]. The involvement of the carbocatio-nic intermediate results in a complex mixture of isomeric alkenes [27,28] and intramolecular and intermolecular dehydration (alkene and ether formation, respectively) are often parallel processes. For example, aluminum phosphates with P/Al < 1 yield a mixture of alkenes and ethers whereas those with P/Al > 1 give alkenes selectively [6,29]. Dehydration activity usually correlated with surface acidity [29-31]. The strongly acidic sites of AIPO4 were found to promote alkene formation [26]. 

A detailed study of reactions between dialkyl phosphite anions and nitrobenzyl bromides has been described. In reactions between the halides and the phosphites (RO)2PONa in a solvent (THF, PriOH, or MeOD) the observed products (Z = 2-, 3-, or 4-nitro), apart from phosphonic diester (104), are those of reduction, (105) or (106), coupling (107), and ether formation (108). Phosphonate formation was moderate for Z = 2-nitro (R = Me), rather higher (51-97% isolated yields) for Z = 3-nitro (R = Me or Pr ), but extremely low for Z = 4-nitro (R = Me) and absent for R = Pr . In all cases when R = Me, ether formation also occurred. In cases where the yields of phosphonate were low, the yields of (107) were correspondingly high, and vice versa. Reactions performed in darkness, daylight or UV, produced little variation in the yields of phosphonate ester (R = Me) for Z = 3-nitro, but for Z = 2-nitro- or 4-nitro-, no diisopropyl phosphonates were obtained under various conditions. Probable mechanisms of reaction were discussed. ... 

HiSOj/lSO C shorter route, but more prone to side reactions, e.g.. rearrangements and ether formation. (2) PBr3. then K -OC(CH3)3 two steps instead of one but the only side reaction is SN2 to give an ether in the second step, usually only a minor complication. 

The first total synthesis of Cet /ojc is that of Masanao Matsui. [228] The starting material is )8-ionone [229] its side-chain double bond can be hydrogenated regioselectively on a copper catalyst. The side-chain is then extended by three carbon atoms by means of a Darzens reaction [230], followed by a Knoevenagel condensation. The (JS/Z)-isomeric mixture (1 1) of acids is separated by fractional distillation of their ethyl esters the ( )-isomer is hydrolysed and cyclised with trifluoroacetic add to sclareolide. Reduction of the latter with Vitride (sodium bis(2-methoxyethoxy)aluminium hydride) and ether formation then produces Cetalo . ... 

The glucuronic acid derivative (40) was prepared by treating the 6,3-lactone with BaO, Ba(OH)2 and benzyl bromide in DMF, whereby both lactone opening and ether formation occurred in situ.59... 

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