Bromoethane synthesis

Vlayl fluoride [75-02-5] (VF) (fluoroethene) is a colorless gas at ambient conditions. It was first prepared by reaction of l,l-difluoro-2-bromoethane [359-07-9] with ziac (1). Most approaches to vinyl fluoride synthesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (2—5) or utilizing catalysts (3,6—10). Other routes have iavolved ethylene [74-85-1] and HF (11), pyrolysis of 1,1-difluoroethane [624-72-6] (12,13) and fluorochloroethanes (14—18), reaction of 1,1-difluoroethane with acetylene (19,20), and halogen exchange of vinyl chloride [75-01-4] with HF (21—23). Physical properties of vinyl fluoride are given ia Table 1. 

Rank the following halides in order of their reactivity in the Williamson synthesis (a) Bromoethane, 2-bromopropanc, bromobenzene 1 (b) Chloroethane, bromoethane, 1-iodopropene... 

Thus, the acetoacetic ester synthesis of 2-pentanone must involve reaction of bromoethane. 

Synthesis of bromoethane (ethane + HBr) and of dibutyltin dibromide (bromobutane + Sn). Other halogenation reactions such as bromina-tion of p-xylene to tetrabromoxylenes is of importance as an efficient fire extinguishing agent for plastics. 

SYNTHESIS (from 5-methoxytryptamine) A solution of 0.95 g of free-base 5-methoxytryptamine was dissolved in 10 mL warm I PA and, after returning to room temperature, treated first with 2.8 mL diisopropylethylamine followed by 1.2 mL bromoethane. After 3 days, TLC showed considerable starting material, so there was added an additional 2.8 g of the amine and 1.2 g of the bromide and the room-... 

A facile route to isothiochromans involves the base-catalyzed reaction of a benzyl dibromide with an a-thiocarbonyl compound. The method has been extended to the synthesis of an anthraceno[2,3-f]thiopyran, a heterocyclic analogue of an anthracyclinone (Equation 169) <1994S363>. In like manner, alkylation of the 2-aryl-1-bromoethane 491 by thiourea and subsequent liberation of the thiol function creates an isothiochroman precursor. An intramolecular Michael addition to the cr, )-unsaturated ester side chain yields the 1-substituted heterocycle (Scheme 179) <1992JOC1727>. 

These procedures were then repeated for the synthesis of [C4mim][NTf2] by replacing 1-bromoethane with 1-bromobutane, in the alkylation reaction with 1-methylimidazole. 

Write out a synthesis of l-(3-bromophenyl)-l-bromoethane from benzene. 

Ester enolates undergo alkylation reactions. When ethyl 3-methylpentanoate (110) reacts with sodium ethoxide in ethanol and then with bromoethane, the product is 111. Alkylation of malonate derivatives leads to an interesting sequence of reactions that are useful in synthesis. The reaction of diethyl malonate (90) and NaOEt in ethanol, followed by reaction with benzyl bromide, gives 112. In a second reaction, 112 reacts with NaOEt in ethanol and then with iodomethane to give 113. Saponification of 113 (see Chapter 20, Section 20.2) gives the dicarboxylic acid, 114, and heating leads to decarboxylation (Section 22.8) and formation of acid 115. This overall sequence converted malonic acid via the diester to a substituted carboxylic acid, and it is known as the malonic ester synthesis. 

Synthesis Our starting materials for this synthesis of cis-3-hexene are acetylene and bromoethane, both readily available compounds. This synthesis is carried out in five steps as follows. 

Scheme 10.2. The Gabriel synthesis using bromoethane (CH3CH2Br) on reaction with phthalimide [1,2-benzenedicarboxunide or lH-isoindole-l,3(2H)-dione] in the presence of base to produce ethanamine. The solvent is shown as dimethylformamide (DMF).

Nucleophilic substitution reactions are important in organic synthesis because the halogen atom on halogenoalkanes can be replaced by other functional groups. The reaction with potassium cyanide is a good illustration of this. The cyanide ion reacts to form a nitrile. For example, bromoethane reacts by an Sj42 mechanism with a solution of potassium cyanide in ethanol to form propanenitrile ... 

Two novel routes to triethylborane have been reported. Irradiation of bromoethane and aluminium powder with ultrasound gives ethyl aluminium sesquibromide which on treatment with triethoxyborane gives triethylborane in good yields and a laser initiated gas phase reaction between diborane and ethene gives yields of upto 91%. Allylic boranes have been prepared from allylpotassiiim derivatives and chloroboranes. Hydrolysis leads to the Isomerised olefin and the technique has been used to transform (+)-a-pinene into (+)-3-pinene. Condensation reactions between allylboranes and acetylenes have been developed into a convenient method for the synthesis of bicyclo[3.3.l]nonane derivatives. Mainly linear alkyl derivatives of 9-BBN have been synthesised from the, reaction of iron carbonyls and the organoborane in a Fischer-Tropsch type reaction. ... 

The first synthesis of vinyl fluoride (VF) was reported by Swartz by the reaction of 1,1 -difluoroethane-2-bromoethane with zinc.1 1 Dehalogenation by zinc yields vinyl fluoride ... 

On the basis of this analysis, write a forward scheme for the synthesis of A, starting with 1,3-butadiene, bromoethane, and D as the sources of carbon. 

Now, let s draw out the forward scheme. This multi-step synthesis uses three equivalents of ethylene (labeled A, B, C in the scheme below) and one equivalent of acetic acid (labeled D). Ethylene (A) is converted to 1,2-dibromoethane upon treatment with bromine. Subsequent reaction with excess sodium amide produces an acetylide anion which is then treated with bromoethane [made tfom ethylene (B) and HBr] to produce 1-butyne. Deprotonation with sodium amide, followed by reaction with an epoxide [prepared by epoxidation of ethylene (C)] and water workup, produces a compound with an alkyne group and an alcohol group. Reduction of the alkyne to the cis alkene is accomplished with H2 and Lindlar s catalyst, after which the alcohol is converted to a tosylate with tosyl chloride. Reaction with the conjugate base of acetic acid [produced by treating acetic acid (D) with NaOH] allows for an Sn2 reaction, thus yielding the desired product, Z-hexenyl acetate. 

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