Ethers, alkyl haloalkyl

Selective haloalkylation of aromatic compounds has also been achieved by employing alkyl haloalkyl ethers as the haloalkylating agents, as seen from equations (88) and (89). However, the use of chlo-romethyl ethers in chloromethylation (equation 89) is discouraged due to the carcinogenic nature of the ether substrate. As an alternative, chloromethylation reactions can also be carried out using paraformal-dehyde-HCl in the presence of ZnCh or SnCU as catalyst. ... 

The most frequentiy used halo alkylating agents are aldehydes and hydrogen haUdes, haloalkyl ethers, haloalkyl sulfides, acetals and hydrogen haUdes, di- and polyhaloalkanes, haloalkenes, haloalcohols, haloalkyl sulfates, haloalkyl -tosylates, and miscellaneous further haloalkyl esters. Haloalkylations include halomethylation, haloethylation, and miscellaneous higher haloalkylations. Under specific conditions, bis- and polyhaloalkylation can also be achieved. 

The method most often used for preparation of alkyl 1-haloalkyl ethers (cf. also page 169) is the Henry reaction (a) dry HC1 is led into a well cooled equimolar mixture of... 

Isolation of alkoxyphosphonium intermediates has been achieved recently by the use of reagents which enter into the Michaelis-Arbuzov reaction at room temperature or below. Thus, Abramov et al. (3,4,8) obtained noncrystalline adducts from trialkyl phosphites and o ,iS-di-haloalkyl ethers. Razumov and Bankovskaya (278) found that reaction of alkyl dialkylphosphinite esters with alkyl halides carried cut at low temperature gave crystalline 1 1 adducts convertible to phosphine oxides on gentle warming. These latter adducts were sufficiently stable Tor measurement of their dipole moments and other properties. They should prove valuable for the study of valency expansion. Also of potential value for this purpose are the stable trialkoxyphosphonium fluoroborates (96,97), e.g., [EtP(OEt)s] BF4 , obtained by interaction of EtsO BF4" or Ph3C+ BF4 with phosphites at room temperature. 

The reaction of an alcohol with a vinyl ester proceeds much faster than with an alkyl ester or a haloalkyl ester to form the desired product in higher yields Kobayashi and co-workers [36-41] studied the polymerisation of the divinyl esters of dicarboxylic acids with diols, triols and sorbitol. The polymerisation behaviour was strongly dependent on the monomer structure, enzyme origin and reaction conditions. Under appropriate conditions, an aliphatic polyester with a MW higher than 2 x lO Da was obtained. The polymerisation of divinyl adipate with 1,4-BDO by PFL, in isopropyl ether at 45 °C for 48 h, produced a polyester with a MW of 6,700 Da and a yield of 50% (Scheme 12.8, [1]), whereas the use of CAL was also employed to produce crosslinkable polyesters [40]. Divinyl sebacate and glycerol were polymerised in the presence of the unsaturated fatty acids, oleic acid, linoleic acid and linoleinic acid. NMR analysis revealed that the reaction proceeded with regioselectivity during the... 

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