Benzyl chloride mechanism

A 250-mL, three-necked, round-bottomed flask is equipped with a mechanical stirrer, a reflux condenser fitted with a drying tube, and a stopper. The flask is charged with 14.3 g (0.1 mol) of 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole, 12.7 g (0.1 mol) of freshly distilled benzyl chloride, and 50 mL of dry acetonitrile. The mixture is heated at reflux for 24 hr and cooled to room temperature. Crystallization is induced by scratching or... 

In a 3-I. three-necked flask, fitted with a mechanical stirrer, a reflux condenser, and a separatory funnel, are placed 24.3 g. (i gram atom) of magnesium turnings, 500 cc. of absolute ether, a crystal of iodine, and a 5- to lo-cc. portion of 126.5 g- cc., I mole) of freshly distilled benzyl chloride (b.p. 177-179°). In a few minutes the reaction starts (Note 1) and is controlled if necessary by cooling with a wet towel. The stirrer is started and the balance of the benzyl chloride is run in as fast as the refluxing will permit. The addition requires from one to two hours, and when completed the mixture is refluxed ofi the steam bath with stirring for three hours. With the stirrer stUl running, 182 g. (r mole) of benzophenone (Org. Syn. Coll. Vol. i, 89) dissolved in 500 cc. of absolute ether is added at such a rate that the mixture refluxes rapidly. This requires about twenty minutes and then the reaction mixture is allowed to stand for two hours (Note 2). 

Benzyl chloride can be converted into benzaldebyde by treatment with nitromethane and base. The reaction involves initial conversion of nilro-methane into its anion, followed by SN2 reaction of the anion with benzyl chloride and subsequent E2 reaction. Write the mechanism in detail, using curved arrows to indicate the electron flow in each step. 

A 1500-cc. flask is fitted with a reflux condenser, a mechanical stirrer, and a 200-cc. separatory funnel. In the flask arc placed 372 g. (4 moles) of aniline (Note 1), 105 g. (r.25 moles) of sodium bicarbonate (Note 2) and roocc. of water. The flask and contents are then heated on a steam bath to 90-95°, and r27 g. (1 mole) of benzyl chloride (Note 3) is run in slowly from the separatory funnel, vigorous agitation being maintained. The addition of benzyl chloride should take not less than one and one-half to two hours, and the reaction is complete in four hours. 

Co(TPP) has been demonstrated to act as a catalyst for the electrocarboxylation of benzyl chloride and butyl bromide with CO - to give PhCHiCfOiOCH Ph and Bu0C(0)C(0)0Bu, respectively. The propo.sed mechanism involved Co(TPP)R and [Co(TPP-N-R) as intermediates (the latter detected by spectroscopy) in the catalytic production of free R or R-, which then reacted directly with Co(TPP) precipitated on graphite foil has been successfully used for the determination of organic halides, including DDT and 1,2,3,4,5,6-hexachlorocyclohexane (lindane), to sub-ppm level in aqueous solution. Deoxygenation of the solutions is not required, and the technique is moderately insensitive to the ionic composition of the solution. ... 

The acetone-sensitized photodehydrochlorination of 1,4-dichlorobutane is not suppressed by triplet quenchers (20), but the fluorescence of the sensitizer is quenched by the alkyl chloride (13). These observations imply the operation of a mechanism involving collisional deactivation, by the substrate, of the acetone excited singlet state (13,21). This type of mechanism has received strong support from another study in which the fluorescence of acetone and 2-butanone was found to be quenched by several alkyl and benzyl chlorides (24). The detailed mechanism for alkanone sensitization proposed on the basis of the latter work invokes a charge-transfer (singlet ketone)-substrate exciplex (24) and is similar to one of the mechanisms that has been suggested (15) for sensitization by ketone triplets (cf. Equations 4 and 5). 

The first clue to the existence of the SrnI mechanism came from product studies both in aliphatic and aromatic cases. It was noticed that in the reaction of benzyl and substituted benzyl chlorides with the 2-nitropropane anion, oxygen alkylation, yielding the oxime and then the aldehyde, occurs exclusively in the case of benzyl chloride and 3-nitrobenzyl chloride, whereas, with 4-nitrobenzyl chloride, the yield of aldehyde is only 6% and the carbon-alkylated (104) product is obtained in 92% yield (Kornblum, 1975). This was interpreted as the result of a competition between 8, 2 (O-alkylation) and S l (C-alkylation) reactions. In the aromatic case, it was observed that the reaction of 5- and 6-halopseudocumenes with KNHj in liquid ammonia (Kim and Bunnett, 1970) forms the 5- and 6-pseudocumi-dines in a ratio which is the same whether the starting compound is the 5- or 6-isomer in the case of the chloro- and bromo-derivatives, as expected from an aryne mechanism (Scheme 9), whereas much more non-rearranged... 

Benzyl chloride hydrolysis proceeds via a third mechanism (Sj.1). Results of studies of benzyl chloride hydrolysis ( 1) in distilled water and EPA-13 and EPA-2 sediment/water systems are summarized in Table V. Results for this compound include only overall first-order disappearance rate constants, but the data clearly show that the hydrolysis rate is independent of the fraction sorbed to sediment. Thus, the conclusion is again made that neutral hydrolysis proceeds via similar rate constants in both the aqueous and sediment-sorbed phases. 

Thermal decomposition of allylbenzene ozonide (58) at 37°C in the liquid phase gave toluene, bibenzyl, phenylacetaldehyde, formic acid, (benzyloxymethyl)formate, and benzyl formate as products. In chlorinated solvents, benzyl chloride is also formed and in the presence of a radical quench such as 1-butanethiol, the product distribution changes. Electron spin resonance (ESR) signals are observed in the presence of spin traps, adding to the evidence that suggests radicals are involved in the decomposition mechanism (Scheme 9) <89JA5839>. 

Reactions (30) and (31) may give the same products. In (31) the polarization energy decreases the energy demand for temporal charge separation and it can be exothermic when B has a considerable electron affinity. For aromatic hydrocarbon quenchers (e.g., anthracene) such mechanism leads to dissipation of the excitation energy on the vibrational levels. When the quencher molecules contain Cl or Br atom in the intermediate step, Cl or Br elimination is expected, e.g., with benzyl chloride additive ... 

Kinetics and Mechanism of Reactions of Bis (methyl-2,2 -dimercaptodiethyl-amine) dinickel(II) with Alkyl Halides. The rates of reaction of [Ni2 CH3N-(CH2CH2S)2 2], structure III, with methyl iodide, benzyl bromide, benzyl chloride, p-chlorobenzyl chloride, and p-nitrobenzyl chloride have been studied as functions of temperature and concentration in chloroform (3). Absorbance measurements were utilized to determine the rates. All experiments were conducted with excess alkyl halide (20 to 1000 times the initial concentration of complex). Jicha and Busch (18) were able to isolate alkylated complexes of the composition... 

For Sn2 reactions no such simple correlations are found.283 In this mechanism bond breaking is about as important as bond making in the rate-determining step, and substituents have an effect on both processes, often in opposite directions. The unsubstituted benzyl chloride and bromide solvolyze by the Sn2 mechanism.282... 

A suspension of potassium amide (0.23 mole) in liquid ammonia is prepared in a 1-1. three-necked flask equipped with an air condenser (without drying tube), a ball-sealed mechanical stirrer, and a dropping funnel. Commercial anhydrous liquid ammonia (500 ml.) is introduced into the flask from a cylinder through an inlet tube. To the stirred ammonia is added a small piece of potassium metal. After the appearance of a blue color, a few crystals (about 0.25 g.) of ferric nitrate hydrate are added, followed by small pieces of potassium (Note 1) until 9.0 g. (0.39 g.-atom) has been added. After all the potassium has been converted to the amide (Note 2), 44.6 g. (0.23 mole) of diphenyl-acetonitrile (Note 3) is added and the resulting greenish-brown solution is stirred for 5 minutes. To this is added, over 10 minutes, 30.5 g. (0.24 mole) of benzyl chloride (Note 4) in 100 ml. of anhydrous ether. The orange solution is stirred for 1 hour, and the ammonia is then evaporated on a steam bath as 300 ml. of anhydrous ether is being added. To the ether solution is added 300 ml. of water, whereupon the crude nitrile precipitates. riie ether is then removed by distillation and the crude... 

Due to an accident right before Christmas, an unknown amount of benzyl chloride (BzC) (see Fig. 12.1) is introduced into a small, well-mixed pond that is used as a drinking-water reservoir. Working for the State Water Authority, you are asked to estimate how much BzC has entered the pond, and more importantly, how long it will take until the concentration will have dropped below 1 jUg -L-1. Because of the Christmas holiday, it takes you 5 days until you are ready to make the first measurement. At this time (i.e., 5 days after the spill) the measured BzC concentration in the pond water is 50 jug. L 1. A second measurement 5 days later shows that the concentration has dropped to 23.6 jUg-L-1. Besides answering the above questions, you also want to identify the major removal mechanism(s) for BzC in the pond. Assume that all relevant systems and compound parameters are constant during the relevant time period. 

Comparison of kh with the calculated k,ot = 0.15 d 1 shows that abiotic hydrolysis is the most important removal mechanism for BzC in the pond ( 75%>) thus, you have to worry about the transformation product benzyl alcohol (Fig. 12.1). About 7% is removed by flushing (kw = VIQ = 0.01 d"1), and the rest by other processes. Considering the properties of benzyl chloride (e.g., Kj0Vi, Ajaw, see Appendix C), the most likely additional elimination processes are gas exchange and biotransformation (see later chapters). 

Exercise 8-15 Select the compounds from the following list that would be expected to hydrolyze more rapidly than phenylmethyl (benzyl) chloride by the SN1 mechanism ... 

The reaction of an aryl and an alkyl iodide in presence of complex (103) and the Zn-Cu couple leads to alkyl aryl ketones in good yields (equation 115).492 By-products such as ArR, ArH and Ar2 were found in some cases. Replacement of alkyl iodides by benzyl chlorides gave benzyl ketones, but the formation of by-products due to coupling reactions was significant. Dialkylzinc complexes were formed here and the proposed mechanism is given in Scheme 41. 

Suggest a mechanism for this transformation and predict the structure of the product that would be formed if the same concept were applied to the condensation of 2-(trifluoromethyl)benzyl chloride with 2-benzo[h]thienyllithium. 

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