Bromopropan-2-one

Fig. 13.2. Illustration of the basic concept of Basis Products, (a) The PGVL reaction scheme of VRXN-2-00051 (formation of the H-imidazo[1,2-a]pyridine ring system using aminoheterocycles and alpha-halo ketones) is used for the illustration (b) The Basis Products of A are formed by all A reactants with one constant reactant (B CAP, 1 -bromopropan-2-one). The Basis products of are formed by all reactants with a constant A reactant (A CAP, 2-amino pyridine). The blue triangle and yellow hexagon represent two such basis products. The red star represents a product molecule which is related to those two corresponding basis products.

To a mixture of anhyd ethylene glycol (250 mL) and anhyd KF (168 g, 3.0 mol) in a mechanically stirred 1-L flask fitted with a distillation head and a pressure-equalizing addition funnel was added dropwise l-bromopropan-2-one (1 102 g, 0.75 mol) at 160 C. The crude product 2 distilled from the mixture over a 70— 120 C boiling point range. The crude distillate was dried (K2C03) and then fractionally distilled yield 9.00 g (20%) bp 75-77 "C/760 Torr. 

A database contains specific information, such as that chloropropan-2-one (chloroacetone) vapor irritates the eyes. In response to the question tell me about chloropropan-2-one, a database system can report that it irritates the eyes, or to the question find me a chemical that irritates the eyes can return the answer chloropropan-2-one. If this one entry is the total content of the database, there are few other questions the system can answer. For example, it can return no information about bromopropan-2-one. 

ControUed-potential oxidations of a number of primary, secondary, and tertiary alkyl bromides at platinum electrodes in acetonitrile have been investigated [10]. For compounds such as 2-bromopropane, 2-bromobutane, tert-butyl bromide, and neopentyl bromide, a single Ai-alkylacetamide is produced. On the other hand, for 1-bromobutane, 1-bromopentane, 1-bromohexane, 1-bromo-3-methylbutane, and 3-bromohexane, a mixture of amides arises. It was proposed that one electron is removed from each molecule of starting material and that the resulting cation radical (RBr+ ) decomposes to yield a carbocation (R" "). Once formed, the carbocation can react (either directly or after rearrangement) with acetonitrile eventually to form an Al-alkylacetamide, as described above for alkyl iodides. In later work, Becker [11] studied the oxidation of 1-bromoalkanes ranging from methyl to heptyl bromide. He observed that, as the carbon-chain length is increased, the coulombic yield of amides decreases as the number of different amides increases. 

The acetamido alkenethiolate (416), generated by the reductive cleavage of 2,3-dihydro-l,4-thiazin-2-one (415) in liquid ammonia (cf. p. 625), reacted with l-chloro-3-bromopropane in a two-stage process to give (417). 

V-Ethyl azonan-2-one is readily available by alkylation with the ethyl iodide <1998BML1973>. Similarly, azonane was alkylated with 3-bromopropan-l-ol to afford intermediate alcohol 54 in 45% yield (Scheme 3) <2003T9239>. 

Restricted Internal Rotation of Several Symmetric Tops. The tables of thermodynamic functions for an internal rotation of a single symmetric top may be used for several symmetric tops [with moments of inertia calculated from equation (20)] provided both potential energy and kinetic energy cross-terms between the tops can be neglected. Both assumptions have been generally made in calculations for molecules with several tops. Where there are reliable calorimetric data at one or more temperatures, the tables have been used to calculate appropriate potential barriers. Using this procedure thermodynamic contributions have been calculated for propane, 2-methylpropane, 2,2-dimethylpropane, cis-but-2-ene, rm a -but-2-ene, isobutene, o-xylene, > m-xylene, p-xylene, 1,2,3-trimethylbenzene, > 1,2,4-trimethylbenzene, dimethyl sulphide,2-chloro-2-methylpropane, and dimethyl-amine. In several cases thermodynamic contributions have been calculated using potential barriers estimated from those of related molecules. Examples of this procedure are found in calculations for 2-fluoro-2-methylpropane, 2-chloropropane, 2-bromopropane, 2-iodopro-pane, 2,2-dichloropropane, 2-bromo-2-methylpropane, 2-iodo-2-methylpropane, 1,3,5-trimethylbenzene, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1,2,3,4-tetramethylbenzene, pentamethyl-benzene, and hexamethylbenzene. ... 

All the reactions of 1-bromopropane in the preceding problem give the product of nucleophilic substitution in high yield. High yields of substitution products are also obtained in all but one of the analogous reactions of 2-bromopropane. In one case, however, 2-bromopropane is converted to propene, especially when the reaction is carried out at elevated temperature (about 55°C). Which reactant is most effective in converting 2-bromopropane to propene ... 

To a suspension of sodamide in liquid ammonia and made from sodium in liquid ammonia, there is added fractionally and with stirring phenothiazine. After an hour there is added thereto, while maintaining the stirring, 1-chloro-2-methyl-3-bromopropane, then 700 cc of toluene. The ammonia is then driven off and heating under reflux is carried out for one hour. 

The appearance of turbidity indicates saturation of alkyl halide. In this way both sodium thiosulfate and 2-bromopropane are nearly in a one-phase system, thus shortening significantly the heating period. Furthermore, the competitive hydrogen bromide elimination and the ensuing acid-promoted decomposition of thiosulfate into sulfur and sulfur dioxide are minimized, the checkers added 300 ml. of water over a period of 90 minutes. 

Isopropyl derivatives were introduced by Pettitt and Stouffer [287] and later studied by other workers [288]. They are prepared by reaction with 2-bromopropane in the presence of sodium hydride in dimethyl sulphoxide. The reaction scheme and the preparation procedure were given in Chapter 4 (see p. 64). Except for Arg, all amino acids under study provided the expected derivatives. The hydroxyl group of Hypro was, however, not protected. The derivatives were found to be stable for a reasonable period of time and were analysed on 3% of OV-17. The extension of this promising one-step method to all protein amino acids did not fulfill expectations, however [288]. Some amino acids (Gly, Gin, Asp and Asn) did not provide detectable derivatives and the others led to multiple peaks. Moreover, significant amounts of by-products were produced, which may interfere. Arg provided a single peak, the mass spectrum of which was identical with that of Orn both derivatives resulted from lactam formation. Isoprop derivatives of 23 common amino acids were separated on 5% of-Carbowax 20M on silanized Chromosorb G with temperature programming (50-240°C). 

Figure 4-9 shows the free-radical reaction of propane with bromine. Notice that this reaction is both heated to 125 °C and irradiated with light to achieve a moderate rate. The secondary bromide (2-bromopropane) is favored by a 97 3 product ratio. From this product ratio, we calculate that the two secondary hydrogens are each 97 times as reactive as one of the primary hydrogens. 

In a one-necked round-bottomed flask (250 mL) fitted with a condenser, heat triphenylphosphine (26.2 g, 0.1 mol) with 1-bromopropane (98.4 g, 0.8 mol) under reflux for 2 h. 

Reactions with hydroxyl radicals are considered one of the most efficient ways used by the atmosphere to remove natural and anthropogenic trace gases in the atmosphere [28,29]. Previous kinetics [27,30-32] and modeling studies [2, 33-35] have shown that the primary atmospheric sink of bromopropane is the reaction with OH and that it has an atmospheric lifetime of 10-16 days. Further studies have determined that the lifetime of short-lived species, such as... 

As one might expect, the nucleophilicity of (4) is less than (3), and this difference in reactivity is reflected in the alkylation reaction. (4) reacts readily with activated bromides (allylic, benzylic) and the reactions are complete within 12 hours activated chlorides did not react With primary alkyl iodides the reaction is slow (12-120 hours depending on the chain length). With secondary halides, such as 2-bromopropane, ethyl-2-bromopropionate, (l-bromoethyl)benzene and 2-iodopropane, no alkylation was observed. 

An alkyl halide such as 2-bromopropane has two j8-carbons from which a proton can be removed in an E2 reaction. Because the two j8-carbons are identical, the proton can be removed with equal ease from either one. The product of this elimination reaction is propene. 

Let s look first at the mass spectrum of 1-bromopropane, shown in Figure 13.4. The relative heights of the M and M + 2 peaks are about equal, so we can conclude that the compound contains a bromine atom. Electron bombardment is most likely to dislodge a lone-pair electron if the molecule has any, because a molecule does not hold onto its lone-pair electrons as tightly as it holds onto its bonding electrons. Thus, electron bombardment dislodges one of bromine s lone-pair electrons. 

Bromopropane has two sets of chemically equivalent protons and, therefore, it has two signals in its NMR spectrum. The six methyl protons in 2-bromo-propane are equivalent, so they give rise to only one signal. Ethyl methyl ether has three sets of chemically equivalent protons the methyl protons on the carbon adjacent to the oxygen, the methylene protons on the carbon adjacent to the oxygen. 

If two sets of reagents are available for the synthesis of an alkene, it is better to use the one that requires the less sterically hindered alkyl halide for synthesis of the ylide. Recall that the more sterically hindered the alkyl halide, the less reactive it is in an Sn2 reaction (Section 10.2). Eor example, it is better to use a three-carbon alkyl halide and a five-carbon carbonyl compound than a five-carbon alkyl halide and a three-carbon carbonyl compound for the synthesis of 3-ethyl-3-hexene because it would be easier to form an ylide from 1-bromopropane than from 3-bromopentane. 

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