S-Butyl bromide

A structural isomer has been made, with the butyl group branched at the nitrogen atom. This is N-s-butyl-N-methyltryptamine, or MSBT. It came from a two pass alkylation of N-methyltryptamine (NMT) with s-butyl bromide in isopropylalcohol in the presence of solid potassium iodide. It remained an oil, but was over 90% pure by GCMS, with unreacted NMT being the major impurity. MS (in m/z) C6H14N+ 100 (100%) indolemethylene+ 130 (8%) parent ion 230 (1%). It has been assayed in man, but it remains an unknown. 

SYNTHESIS To a solution of 2.6 g of KOH pellets in 50 mL hot MeOH, there was added a mixture of 6.8 g 2,5-dimethoxythiophenol (see under 2C-T-2 for its preparation) and 5.8 g (s)-butyl bromide. The reaction was exothermic, with the deposition of white solids. This was heated on the steam bath for a few h, the solvent removed under vacuum, and the resulting solids dissolved in 250 mL H20. Additional aqueous NaOH was added to bring universal pH paper to a full blue color. This was extracted with 3x40 mLCH2Cl2, the extracts pooled, and the solvent removed under vacuum. The residue was 2,5-dimethoxyphenyl (s)-butyl sulfide which was a pale yellow oil, weighing 10.12 g. It was sufficiently pure for use in the next reaction without a distillation step. 

Cognate preparations. s-Butyl bromide (2-bromobutane). The quantities required are as for butyl bromide but with butan-2-ol (b.p. 99-100 °C) replacing the butan-l-ol. Two to three washings with concentrated hydrochloric acid are necessary, i.e. until the volume of the acid layer remains unchanged on shaking with halide. The yield of s-butyl bromide, b.p. 90.5-92.5 °C, is 150 g (92%). 

SYNTHESIS To a solution of 2.6 g of KOH pellets in 50 mL hot MeOH, there was added a mixture of 6.8 g 2,5-dimethoxythiophenol (see under 2C-T-2 for its preparation) and 5.8 g (s)-butyl bromide. The reaction was exothermic, with the deposition of white solids. This was heated on the steam bath for a few... 

Finally, use the relative amounts of the different cation conformers along with the reactivity preference of each conformer to determine the overall enantioselectivity of the addition reaction. Do you expect more R or S 2-butyl bromide to form Explain how you arrived at this answer. 

In the first systematic study on nucleophilic substitutions of chiral halides by Group IV metal anions, Jensen and Davis showed that (S )-2-bromobutane is converted to the (R)-2-triphenylmetal product with predominant inversion at the carbon center (Table 5)37. Replacement of the phenyl substituents by alkyl groups was possible through sequential brominolysis and reaction of the derived stannyl bromides with a Grignard reagent (equation 16). Subsequently, Pereyre and coworkers employed the foregoing Grignard sequence to prepare several trialkyl(s-butyl)stannanes (equation 17)38. They also developed an alternative synthesis of more hindered trialkyl derivatives (equation 18). 

Use a descriptive title for your experiment. n-Butyl Bromide. So what Did you drink it Set it on fire What The Synthesis of 1-Bromobutane from 1 -Butanol—now that s a title. 

The reactions with non-aromatic substrates follow a variety of mechanisms. In the reaction of Bu3SnK with s- and /-butyl bromides and iodides, a transient absorbing at 400 nm has been observed,90 and the Bu4Sn and Bu3SnSnBu3 that were formed showed a CIDNP effect, confirming the intermediacy of the Bu3Sm radical.91... 

FIGURE 3.30. Reaction of iron(0) and iron(I) pophyrins with n-, s-, and r-butyl bromides. The chart shows the various porphyrins and their symbolic designations. iron porphyrins, aromatic anion radical, lines best-fitting parabolas through the aromatic anion radicals data. Dashed lines outer-sphere curves obtained by use of the Morse curve model (Section 3.2.2). Adapted from Figure 4 in reference 47b, with permission from the American Chemical Society. 

Analysis of the transition state in terms of energy is certainly a key aspect of the S 2-ET problem. Entropy considerations may, however, bring about additional information, possibly helping us to conceive better the transition between the two mechanisms. It was observed in this connection that, whereas the entropy of activation of both the anthracene anion radical and of the ETIOPFe(O) porphyrin (pp. 99, 100) (which have about the same standard potential) is close to zero in their reaction with s- and t-butyl bromides a definitely negative value, ca. — 20 eu is obtained for the reaction of the porphyrin with n-butyl bromide (Lexa et al., 1988). The same was found for the reaction of two other iron porphyrins, TPPFe(o) and OEP-Fe(i). These activation entropies were estimated from (153), where Z is... 

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