Bromopropane hydrolysis

Dibromo-l-methoxypropane in turn with phenylmagnesium-bromide gave the product, which after hydrolysis yielded l-phenyl-l-methoxy-2-bromopropane. 

To the solution of l-phenyl-l-methoxy-2-bromopropane methylamine was added and as a result of the reaction l-phenyl-l-methoxy-2-methylaminopropane was obtained. After that l-phenyl-l-methoxy-2-methylaminopropane on hydrolysis with hydrobromic acid yielded 1-phenyl-l-hydroxy-2-methylaminopropane, i.e. racemic pseudoephedrine. The racemic base was resolved, by crystallization of their tartrates, into I- and d-pseudoephedrine. The base l-pseudoephedrine forms white rhombic crystals, melting point 118°C. The salt pseudoephedrine sulfate may be prepeared by... 

A An alcohol can be made from propene in a series of reactions. Alcohols can be made directly by adding water (steam, under pressure plus a hot catalyst of phosphoric acid) to an alkene, but can also be made using a series of reactions by, e.g. propene -I- HBr —> 2-bromopropane (in the absence of air) followed by hydrolysis with a hot dilute solution of sodium hydroxide. (2)... 

For the bimolecuiar hydrolysis of 2-bromopropane with OH in aqueous ethanol, the rate constant decreased by a factor of l. 6 when the proportion of water was raised from 20% to 40%. When a corresponding change in solvent was made for the bimolecuiar hydrolysis of 2-bromopropane with water, the rate increased by a factor of 2.8. Explain these differences. 

The pyrrolinyl- (6-11) and pyrrolyl-substituted (12-13) eudistomin skeletons were first prepared by Rinehart from 1-cyano-P-carboline (145), which can be obtained from the corresponding acid (28). Grignard reaction with appropriately protected 3-bromopropanal (Scheme 4) provided the necessary carbons with appropriate oxidation level for cyclization to either of these ring systems. The pyrrolyl-substituted eudistomins then result upon hydrolysis of the imine and acetal functions with concomitant cyclization in the presence of ammonia. The pyrrolinyl-eudistomins require reduction of the imine to the amine followed by acetal hydrolysis and simultaneous ring closure to isomer 147. Reduction of the imine 147 followed by allylic oxidation with sodium hypochlorite isomerizes 147 to the pyrrolinyl-eudistomin skeleton (149). 

Table 2.8 compares hydrolysis half-lives with half-lives for reaction with sulfur-based nucleophiles for several halogenated aliphatics. These data show that the environmental half-lives for substrates such as 1-bromohexane and 1,2-dibromoethane can be substantially reduced in the presence of HS and polysulfides. Enhanced degradation of 2-bromopropane and 1,1,1-trichloroethane, as well as chloroform and carbon tetrachloride (results not shown) was not observed, suggesting that steric hindrance significantly impedes reaction with the sulfur based nucleophiles (Haag and Mill, 1988a). 

Hg. 14.8 Reactants, transition state and products for the hydrolysis of 1-bromopropane. 

When first 1-bromopropane was codeposited with magnesium at low temperature, followed by bromomethane at the same low temperature, hydrolysis yielded methane exclusively ... 

When bromomethane was added after the mixture of magnesium and 1-bromopropane had been allowed to warm up propane was the only product on hydrolysis ... 

The relative rates of reaction of 2-bromopropane and 2-bromo-2-methylpropane with water to give the corresponding alcohols are shown in Table 7-1 and are compared with the corresponding rates of hydrolysis of their unbranched counterparts. Although the process gives the products expected from an Sn2 reaction, the order of reactivity is reversed from that found under typical Sn2 conditions. Thus, primary halides are very slow in their reactions with water, secondary halides are more reactive, and tertiary halides are about 1 million times as fast as primary ones. 

In all cases where substitution and elimination compete, higher reaction temperatures lead to greater proportions of elimination products. Thus, the amount of elimination accompanying hydrolysis of 2-bromo-2-methylpropane doubles as the tenpCTature is raised from 25 to 65"C, and that from reaction of 2-bromopropane with ethoxide rises from 80% at 25"C to nearly 100% at 55"C. Explain. 

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