1- Bromobutane synthesis

We see that a secondary alkyl halide is needed as the alkylating agent The anion of diethyl malonate is a weaker base than ethoxide ion and reacts with secondary alkyl halides by substitution rather than elimination Thus the synthesis of 3 methylpentanoic acid begins with the alkylation of the anion of diethyl mal onate by 2 bromobutane... 

This reaction sequence is called the acetoacetic ester synthesis. It is a standard procedure for the preparation of ketones from alkyl halides, as the conversion of 1-bromobutane to 2-heptanone illustrates. 

Solution The synthesis can be completed in four steps from acetylene and 1-bromobutane ... 

At stage 1 of the synthesis, m-bromoanisole [1] and n-butyUithium are converted via bromo/lithium exchange in order to obtain m-lithium anisole [2] and n-bromobutane. At stage 11, the reaction mixture is treated with dimethylformamide, and then the reaction is quenched using 3 M hydrochloric acid. Tetrahydrofurane is used as solvent at both synthetic stages. 

Synthesis of 2-bromobutane from compounds of two carbon atoms or fewer Retrosvnthetic Analysis... 

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. 

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. 

Tundo, P. and Selva, M. (2005). Continuous-flow, gas phase synthesis of 1-chlorobutane (1-bromobutane) from 1-butanol and aqueous HCl (HBr) over silica-supported quaternary phosphonium salt. Green Chem., 7,464-467. 

Korneev and Kaufmann successfully lithiated 2-bromo-l,l-diphenylethylene (46) by bromide-lithium exchange to form 2-lithio-l,l-diphenylethylene (47). A second lithia-tion could be effected in four hours at room temperature by deprotonation of the aromatic ring with w-butyllithium in the presence of TMEDA (Scheme 17). Like in the synthesis of compound 23, the first lithiation activates the ortho-hydrogen atom of the Z-phenyl substituent to give 1,4-dilithium compound 48. In total, three equivalents of the alkyl-lithium base are required the third equivalent is consumed in the trapping reaction of w-bromobutane with generation of octane. 

Kopecky s synthesis of trimethyldioxetane employed the base-mediated dehydrohalogenation of 2-methyl-2-hydroperoxy-3-bromobutane. Subsequently, this type of eliminative cyclization (14) has been applied to the preparation of scores of dioxetanes. Additionally, many dioxetanes have been prepared by the addition of singlet oxygen to electron-rich olefins which do not possess allylic hydrogens (15), a method discovered first by Bartlett and Schaap... 

Devise a synthesis of each compound using 1 -bromobutane (CH3CH2CH2CH2Br) as the only organic starting material. You may use any other inorganic reagents. 

After a chemical reaction has been carried out the organic product is often separated from inorganic substances by liquid/liquid extraction. For example, in the synthesis of 1-bromobutane (Chapter 15)... 

In a synthesis experiment, the point of the exercise is to prepare a clean sample of the product you want. All the operations in the lab (e.g., distillation, recrystallization) are just means to this end. The preparation of 1-bromobutane is a classic synthesis and is the basis of the next series of handwritten notebook pages. 

Plausible mechanism for stereoselective synthesis of 3-bromobutan-2-yl benzoate is as following (Fig. 12.64). 

A synthesis of 2-butanol was performed by treating 2-bromobutane with hot sodium hydroxide solution. The yield was 60%, indicating that a significant portion of the reactant was converted into a second product. Predict what this other product might be. 

If boron of an alkylborane could be replaced with a halogen, the product would be an alkyl halide. However, reaction of alkylboranes (neat) with chlorine, bromine, or iodine is very difficult. a when halogenation is done with bromine or iodine dissolved in dichloromethane, however, the reaction is fast and is synthetically useful.A simple example is the reaction of alkenes with boranes followed by addition of bromine, which leads to the alkyl bromide. An example is taken from the synthesis of 2-bromobutane (70) from 2-butene in 88% yield. 0 jhe bromination occurs by a free radical mechanism. Initial reaction with bromine generates a... 

It has been found [117] that polyethylene glycol (PEG) produces a strong catalytic effect during the reaction of butyl bromide with KI. The yield of the butyl iodide product increases linearly with an increase in the length of the PEG chains. A similar acceleration of the reaction between solid potassium phenolate and 1-bromobutane is observed in toluene in the presence of oligoethylene glycols [178]. The synthesis of 8 esters based on alcohols and phenols in two-phase system liquid-liquid catalyzed by PEG is discussed [178a]. 

Fig. 4. Stereoview of a molecule of (R)-2-bromobutane single-positioned in a dissymmetric cage build of (M)-TOT molecules The envelope of TOT is represented by the —1 e contour of sections in a three-dimensional synthesis. The contour has been selected so as to assign an average radius of 1.4 A to the carbonyl oxygens whose unique position is indicated by an arrow. The apparent volume accessible to the guest is slightly overestimated relative to that circumscribed by a conventional van der Waals envelope. The Br and H atoms are depicted by spheres of radius 2.0 and 1.2 A respectively. The orientations of the ctystallographic axes are as shown in Fig. 3. The dotted line denotes the crystallographic twofold axis...

SECTION 24.5 Molecules that possess nonsuperimposable mirror images are termed chiral. The two nonsuperimposable forms of a chiral molecule are called enantiomers. In carbon compounds a chiral center is created when all four groups bonded to a central carbon atom are different, as in 2-bromobutane. Many of the molecules occurring in living systems, such as the amino acids, are chiral and exist in nature in only one enantiomeric form. Many drugs of importance in human medicine are chiral, and the enantiomers may produce very different biochemical effects. For this reason, synthesis of only the effective isomers of chiral drugs has become a high priority. 

If we have available (/ )-2-bromobutane, we can carry out the following synthesis ... 

Consider a problem in which we are asked to outline a synthesis of 2-bromobutane from compounds of two carbon atoms or fewer. This synthesis, as we shall see, involves construction of the carbon skeleton, functional group interconversion, and control of regiochemistry. 

Bromobutane could also be synthesized from compounds of two carbons or fewer by a route in which )- or (Z)-2-butene is an intermediate. You may wish to work out the details of that synthesis for yourself... 

ANSWER Retrosynthetic disconnection of 5-nonanone suggests butylmagnesium bromide and pentanenitrile as immediate precursors. Butylmagnesium bromide can, in turn, be synthesized from 1-bromobutane. Pentanenitrile can also be synthesized from 1-bromobutane, via Siyf2 reaction of 1-bromobutane with cyanide. To begin the synthesis, 1-bromobutane can be prepared from 1-butanol by reaction with phosphorus tribromide. 

The use of acetals as carbonyl-protecting groups is illustrated by the synthesis of 5-hydroxy-5-phenylpentanal from benzaldehyde and 4-bromobutanal ... 

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. 

One possible synthesis of the TM begins with the reaction of 2-bromobutane with NaCN. Hydride reduction of the resulting nitrile affords 2-methylbutan-1-amine. Addition of benzoyl chloride and reduction of the resulting amide product installs the second alkyl group on the secondary amine TM. 

---