1-Bromo-l-chloroethane

Chloroethyl bromide (l bromo-2-chloroethane) [ 107-04-0j M 143.4, b Khi-lOO. Washed with cone H2SO4, water, 10% Na2C03 soln, and again with water, then dried with CaCl2 and fractionally distd before use. 

Substitution of somewhat more complex side chains on the imidazole nitrogen of the purines leads to CNS stimulant drugs that have also been used as vasodilators and antispasmodic agents. Thus, alkylation of theophyline (2) with ethyl bromoacetate followed by saponification of the product gives acephylline (9). Alkylation with l-bromo-2-chloroethane gives the 2-chloroethyl derivative (10). Reaction of that intermediate with amphetamine yields fenethylline (11). ... 

Formation of angular-substituted dimethylene-bisimidazole derivatives 386 has been achieved by reaction of the parent bisimidazole 385 with either l-bromo-2-chloroethane or 1,2-dibromoethane (Equation 102) <1997CJC28>. Reaction of the bisimidazole with a bis-chloroiminium salt has also been used to generate a related core structure <2006T731>. 

The Williamson ether synthesis remains the most practical method for the preparation of tetrahydrofurans, as can be exemplified by the two examples shown in the following schemes. A simple synthesis of 2-substituted tetrahydrofuran-3-carbonitriles 84 is achieved by generating the alkoxide under a phase transfer condition via reaction between 4-chlorobutyronitrile and non-enolizable aldehydes <00SL1773>. A synthesis of 2-alkylidene-tetrahydrofuran 85 was recorded, in which a dianion can be generated through treatment of the amide shown below with an excess of LDA, and is followed by addition of l-bromo-2-chloroethane. In this way, the more basic y-carbon is alkylated and leads eventually to the nucleophilic cyclization <00SL743>. 

Problem 12.28 Sketch the nmr spectra of (a) 1,1-dichloroethane, (b) 1,1,2-trichloroethane, (c) 1,1,2,2-tetrachloroethane and (d) l-bromo-2-chloroethane. In each case indicate the staircase" curve of relative areas. 

The work with l-bromo-2-chloroethane allowed the influence of the nature of the halogen on its reactivity to be observed as either vinyl bromide or vinyl chloride are formed. The ratio of the chloride to the bromide in the products changed with the nature of the catalyst, being around 0.1 for sulphates of Ni, Co, Mn, Cu, Zn and for silica—alumina, 0.6 for alumina and 5 for KOH—Si02 [179]. 

For example, the rate of displacement of bromide by thiophenoxide ion in l-bromo-2-chloroethane is slowed down by a factor of 5 compared to substitution in the structurally similar 1-bromopropane (Equations 4.13 and 4.14).33 But the... 

A final approach to the c -3a-arylhydroindole skeleton that has resulted in a concise total synthesis of ( )-epielwesine (449) featured the acid-promoted cyclization of (Z)-vinylsilane imines such as 575 (Scheme 53) (2/9). Thus, sequential alkylation of 3,4-(methylenedioxyphenyl)acetonitrile (432) with (Z)-4-bromo-l-butenyltrimethylsilane and l-bromo-2-chloroethane provided... 

Substituted thieno[3,4-d]pyrimidine-2(l//),4-diones 306 and 312 were alkylated at position 1 with alkyl halides, in DMF, DMSO or THF, in the presence of sodium hydride (87USP4670560 88JMC1786 90JHC1761 91 Mil). The alkylation of compound 303 with ethyl bromoacetate in DMF in the presence of sodium hydride produced derivative 381 (93MI1). Alkylation of N-3-protected thieno[3,4-d]pyrimidine 320 with l-bromo-2-chloroethane in dimethyl sulfoxide containing sodium hydride, afforded 1 -(2-chloroethyl)-3-(2,4-dime thoxyphenylmethyl)thieno [3,4-d] pyrimidine-... 

FIGURE 3.46 (A) Newman projection of the staggered rotamers of a molecule with a methyl group attached to a chiral sp3 carbon atom. (B) l-Bromo-l,2-dichloroethane. (C) l-bromo-2-chloroethane. 

Under analogous conditions l/f-indole-3-thiol reacts with l-bromo-2-chloroethane to give A, -divinylindole 221 in... 

Chloroethyl thiocyanate, ClCHjCHiSCN (1). Mol. wt. 121.58, b.p. 87 88 /18 mm. This substance is obtained by reaction of potassium thiocyanate with l-bromo-2-chloroethane in refluxing methanol (77-88% yield). 

The cyclization of the dianions of some 1,3-dicarbonyl compounds with l-bromo-2-chloroethane led to the generation of a number of 2-alkylidenetetrahydrofurans with good regio- and... 

Garrot B., Couderc G., Simonot-Grange M.-H., and Stoeckli F., Co-adsorption of 1,2-dichloroethane and l-bromo,2-chloroethane on zeolite ZSM-5 ftom the liquid and vapour phases, using the Myers-Prausnitz-Dubinin model, Microporous and Mesoporous Materials 52 (2002) pp. 199-206. 

With regard to the reagents used in this type of cyclopropanation, 1,2-dibromoethane has been used most frequently. l-Bromo-2-chloroethane, however, may give better yields in some cases. 2-Chloroethylsulfonium iodide is used in the reaction of cyclic ketones to give the spiro derivatives . The use of vinylogous derivatives of 1,2-dihalides allows a synthesis of vinylcyclopropanes (equation 89) . (Chloromethyl)oxirane provides substituted cyclopropylmethanols (equation Oxiranes may also be used in place of... 

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