ChemicalBook CAS DataBase List 2-BROMO-1-PHENYLPROPANE

2-BROMO-1-PHENYLPROPANE synthesis

10synthesis methods

Product Name:2-BROMO-1-PHENYLPROPANE
CAS Number:2114-39-8
Molecular formula:C9H11Br
Molecular Weight:199.09

Benzoic acid, 2-[(1-methyl-2-phenylethoxy)sulfonyl]-, 2-(2-methoxyethoxy)ethyl ester

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2114-39-8
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Yield:2114-39-8 96%

Reaction Conditions:

with lithium bromide in acetone; for 2 h;Product distribution / selectivity;Heating / reflux;

Steps:

Table 2. Comparison of the rates of lithium, sodium, and potassium bromide additions to various alkyl sulfonates. EPO % Isolated Yield (Reaction Time)^aEntry Substrate LiBr NaBr KBr1 2a 97 (0.I h) 92 (16 h) 50 (24 h)2 2a (DMF) 95 (1.5 h) 93 (3.5 h) 94 (9 h)3 3a 96 (0.75 h) 94 (3 h) 92 (15 h) 4 4a 83 (3 h) 89 (28 h) 38 (24 h) 5 4a (DMF) 93 (10 h) 91 (7 h) 94 (12 h)6 2b 96 (2 h) 11 (30 h)^c 0 (24 h)^c7 4b 81 (1 I h) 16 (30 h)^c 0 (24 h)^c8 2c 97 (1 h) 23 (30 h)^c 0 (24 h)^c 9 4c 95 (24 h)^b 33 (30 h)^c 0 (24 h)^c ^aExcept as noted, all reactions were performed in refluxing acetone. Reactions in DMF performed at room temp. ^Ratio of subsitution to elimination = 7.5:1 ^cOnly product and unreacted substrate remained.[00040] Similar trends were observed in reactions involving lithium bromides in refluxing acetone (Table 2). The NALG sulfonyl ester of 3 -phenyl propanol 2a reacted with LiBr in refluxing acetone to give 3-phenylpropylbromide in 97% yield in 0.1 h whereas the electronically equivalent mefhyl-carboxyphenyl sulfonate required 8 times longer (0.75 h) to give the same yield of product (entries 1 and 3 for LiBr). However, in regard to the reaction of both sodium and potassium bromide with substrates 2a and 3a, a remarkable reversal of selectivity was observed. The reaction of NaBr with 3a was complete (94% yield) in 3 h, whereas the reaction of NaBr with NALG 2a required over five times longer to achieve a similar yield (entries 1 and 3 for NaBr). This is the opposite of the trend observed in the reaction of these same two substrates with LiBr. The reactions of NaBr and KBr with sulfonates derived from secondary alcohols also validate this trend (entries 6 - 9). These data seem to indicate that the diethylene glycol unit of 2a-c favors the chelation of the lithium cation but destabilizes S_N2 reactions involving sodium and potassium salts. Thus, in some embodiments of the invention, the cation M^x+ is preferably Li⁺, whereas in other embodiments of the invention M^x+ may be other cations.