Sodium <>-bromopropionate

Chapter III. 1 Heptene (111,10) alkyl iodides (KI H3PO4 method) (111,38) alkyl fluorides (KF-ethylene glycol method) (111,41) keten (nichrome wire method) (111,90) ion exchange resin catalyst method for esters (111,102) acetamide (urea method) (111,107) ethyl a bromopropionate (111,126) acetoacetatic ester condensation using sodium triphenylmethide (111,151). 

A solution of 18 grams of ethyl 2-bromopropionate in 20 ml of tetrahydrofuran is then added to the cooled reaction mixture. After 24 hours at 20°C, the product is hydrolyzed by adding 200 ml of 5 weight percent methanolic sodium hydroxide followed by heating to reflux for 1 hour. The reaction mixture is then diluted with excess 1 N sulfuric acid and extracted with ether. The ether phase Is separated, evaporated to dryness and the residue is recrystallized from acetone-hexane to yield 2-(6-methoxv-2-naphthyl)propionic acid. 

Carboxy-2-pyridylthio)propionic acids, prepared by the reaction of 2-mercatopyridin-3-carboxylic acid with 3-bromopropionic acid in aqueous KOH, undergo cyclization upon treatment with anhydrous sodium acetate and acetic anhydride to afford 2,3-dihydrothiopyrano[2,3-3]pyridin-4(4//)-ones. These products undergo further reaction with phenylhydrazine to give the phenylhydrazone (isolated) and then Fischer indole cyclization to give novel 5/7,1177-pyrido[2, 3 2,3]thiopyrano[4,3-3]indoles <2000JHC379>. 

Reaction of l-mercapto-4-cyano-5,6,7,8-tetrahydroisoquinolin-3(2//)-one with 3-bromopropionic acid in boiling ethanol in the presence of sodium acetate gave octahydro[l,3]thiazino[2,3-a]isoquinoline-4,6-dione (216) (89PS203). 

The benzylbromomalonic acid containing water is now heated in an oil bath to 125°—130°, and the fused mass evolves carbon dioxide and a certain amount of hydrobromic acid. The reaction is complete in the course of 30—45 minutes. The residue is a yellow oil, which even at a low temperature does not crystallise, and which in the main consists of phenyl-a-bromopropionic acid. For the purpose of purification it is washed with water, taken up in ether, and dried with anhydrous sodium sulphate the ether is then distilled off. The mobile, almost colourless oil remaining is dissolved in 5 times its volume (excess) of 25% aqueous ammonia, and either heated for 3 hours to 100° in a sealed tube or allowed to stand for 3 to 4 days at ordinary temperature. On evaporation of the ammo-niacal solution an almost colourless residue is left, and this chiefly consists of ammonium bromide and phenylalanine. On boiling with absolute alcohol the amino-acid is left undissolved and is recrystallised from hot water. 

A reversed-phase HPLC post-column ion-pair extraction system was developed by Kim and Stewart [71, 72] for the analysis of carboxylic acid drugs and their salts (sodium formate, sodium acetate, 3-bromopropionic acid, 6-aminocaproic acid, 11-bromoundecanoic acid, 1-heptanesulfonic acid, / -n i t rophcny 1 acetic acid, sodium benzoate, sodium salicylate, valproic acid, probenecid, naproxen, ketoprofen, ibuprofen, mefenamic acid, flufenamic acid, and cefuroxime sodium) using a-(3,4-dimethoxy-phenyl)-4,-trimethylammoniummethylcinnamonitrile methosulfate... 

The site at which alkylation occurs depends on the alkylation reagent, the reaction conditions and the nature of the substituents on the azoloazine ring system. Thus, whereas alkylation of compound (114) by alkyl iodides in THF in the presence of sodium hydride gives the products (115), alkylation by ethyl a-bromoacetate or ethyl a-bromopropionate gives the products (116) (Scheme... 

If an ester of o-bromopropionic acid were desired the appropriate alcohol would now be used, but as the acid itself is required, the bromide is decomposed by addition of one and one-third equivalents of water, the mixture being shaken under a reflux condenser, with a pot of ice close at hand, until homogeneous, and finally warmed for one-half hour on the water-bath. The solution is then cooled, treated with several volumes of ether, dried over sodium sulfate, and concentrated. When fractionated in vacuo the residue boils mainly at 1240 under a pressure of 18-19 mm. and solidifies in a freezing mixture, then melting at about 250. The acid should be protected from the moisture of the air. as it is quite hygroscopic. It is also a powerful skin irritant. The yield should be 60 per cent of the bromide used. 

If the sodium chloroacetate in the above preparation is replaced by a-bromopropionic add, the corresponding atninopropionic add derivative is obtained. It has similar properties to the aminoacetic acid compound. 

Problem 28.14 Actually, the door opened by Winstein and Lucas (Sec. 28.10) was already ajar. In 1937, E. D. Hughes, Ingold (p. 460), and their co-workers reported that, in contrast to the neutral acid or its ester, sodium a-bromopropionate undergoes hydrolysis with retention of configuration. 

Sodium o-bromopropionate Give a likely interpretation of these findings. 

B) Preparation of a-Bromopropionic Acid (M.). Arrange a 500-ml Florence flask as shown in Figure 46, without the dropping funnel the absorption train is the same as used in the preparation of chloroacetic acid (page 225). The rubber stopper which connects the reflux condenser to the flask is painted with sodium silicate twice, and allowed to dry each time. 

Addition to methyl acrylate. The ester required for this reaction was obtained from a 60% solution in methanol supplied by Rohm and Haas. This solution was treated with hydroquinone and washed repeatedly with 7% aqueous sodium sulfate solution to remove the methanol, and the ester was dried, filtered, and used without distillation. For the preparation of methyl -bromopropionate, hydrogen bromide... 

Derivation Reaction of sodium sulfide, sulfur, and bromopropionic acid. 

Block copolymers were synthesized with St, MA, and MMA using the homogeneous CuBr/dNbpy catalyst system. The molecular weight of the macroinitiator (Mn=15,400,Mw/Mn=1.39) increased with the formation of the second block (Mn=24,900 to 35,000) and the molecular weight distribution remained narrow (Mw/Mn>1.5) [274]. Difunctional macroinitiators were also prepared. Once the THF polymerization was complete, the polymer was reacted with sodium 2-bromopropionate to produce the ATRP initiator, which was then used for the preparation of block copolymers, again with St, MMA, and MA. For both St and MA, the polymerization leading to the preparation of the second block was incomplete however, it proceeded smoothly for MMA. In both systems, block formation was confirmed through DSC analysis [274]. 

The halogen end group can be transformed into other functionalities by means of standard organic procedures, such as a nucleophilic displacement reaction. Different authors have investigated this process of the nucleophilic displacement reactions with model compounds, to confirm the feasibility and selectivity. Compounds such as 1-phenylethyl halide, methyl 2-bromopropionate, and ethyl 2-bromoisobutane mimic the end groups of PSs, poly(alkyl acrylates), and poly(alkyl methacrylates), respectively. Different compounds have been tested, such as sodium azide, n-butylamine, and n-butylphosphine. 

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