Alkyl benzenes such as toluene (methylbenzene) react with NBS to give products in which bromine substitution has occurred at the position next to the aromatic ring (the benzylic position). Explain, based on the bond dissociation energies in Table 5.3.

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Table 5.3 Some Bond Dissociation Energies, D (kJ/mol) (kJ/mol) (kJ/mol) Bond Bond Bond С-На —снз (CH3)3C-I Н—н 436 209 355 (CHg]2CH -CHз Н-F НаС —Сн—н 570 444 351 НаС— Сн—CI Н-СI (CH3)3C-CH3 432 368 339 Hас — снсH2—н Hас — Сн—сна Н—Br 366 361 406 Нас снсн—снз Hас - снсH2—сI Н- 298 289 310 Hас Сн2 C-CI 243 611 464 CHз Br-Br 193 427 151 CH3-H 438 CI CH— CHз 405 CH3-CI 351 332 CHз—Br 293 CHз-1 234 CH2-H CHз—он 368 380 368 Cнзс —н CHз-NH2 335 СаНs —Н 420 CH2-CI 498 но-н 293 СНо—СI 338 но-он 213 СаН — Br 285 CH30-H 437 СаНs — 222 Вг CH3S-H 371 337 СэН—он 380 СэHоо—н 436 (CH3)2Cн—н 401 (CH3)2CH-CI 339 322 CнзC —CHз но 469 (CH3)2CH-Br 274 (CH])3C—н 390 CH;CH20-CH3 339 НC -С —Н (CHд)3C—CI 330 NH2-H 552 449 CH—CHз H-CN (CH3)3C-Br 263 376 518 .CHз CH2B NBS CCI4