Relative Reactivities of Some Alkyl Halides — Transcript

Full transcript

1. 0:05how's everybody doing today
2. 0:06good good good so today this lab is
3. 0:09um it's a great lab actually so it's
4. 0:13relatively activities of
5. 0:15some alkyl halides and so what we're
6. 0:17going to be doing is pretty much
7. 0:19comparing sn1 and sn2 reactions
8. 0:22but actually in the lab so we've done
9. 0:24this on paper before
10. 0:25uh currently still doing it right so um
11. 0:30what we're going to do today is take a
12. 0:33look at
13. 0:34some of the factors that affect sn1 and
14. 0:37sn2
15. 0:37um so for example when we're looking
16. 0:41trying to like categorize the fact that
17. 0:43different factors
18. 0:44for sn1 and sn2 we look at the first
19. 0:47thing right
20. 0:48alkyl halide the next thing that we
21. 0:50might look at is the nucleophile
22. 0:52uh then the leaving group and then the
23. 0:54solvent right so
24. 0:56these are obviously conditions that'll
25. 0:58promote sn1 or sn2
26. 1:00uh depending on what they are and so
27. 1:03what we're doing today is we will
28. 1:07have the same ten substrates for sn1
29. 1:10and sn2 conditions so the sn2 conditions
30. 1:14are going to have
31. 1:16of course our polar a protic solvent
32. 1:18we're going to use acetone today
33. 1:20and then our choice of nucleophile is
34. 1:23going to be iodide so what we're doing
35. 1:25is adding sodium iodide as our source
36. 1:27for the nucleophile
37. 1:29uh iodide is negatively charged it's a
38. 1:32nucleophile
39. 1:34and then for
40. 1:38so since the solvent and the nucleophile
41. 1:40are going to be the same
42. 1:41the things that we want to focus on when
43. 1:43we're trying to like kind of
44. 1:45analyze the outcomes and assess whether
45. 1:48or not that was
46. 1:49the projected outcome um then what we
47. 1:52want to do is look at the other factors
48. 1:54so
49. 1:55again solvent is the same and
50. 1:58um the nucleophile is going to be the
51. 2:01same and so what we're going to look at
52. 2:02is the leaving group as well
53. 2:04as the am i tripping right now
54. 2:10the aqua halide oh it's a good start yo
55. 2:15so that's for sn2 um we're gonna do the
56. 2:18same
57. 2:18thing in terms of like what we're
58. 2:20looking at for
59. 2:22the projected outcome for sn1 but
60. 2:24obviously our conditions are going to be
61. 2:25different we're going to promote
62. 2:27sn1 by using a polar protic solvent
63. 2:31and so in this case it's going to be
64. 2:34ethanol
65. 2:35okay um but in addition to ethanol what
66. 2:38we actually have
67. 2:39is a silver um silver
68. 2:43nitrate right let me just
69. 2:47double check for sure yeah it's uh
70. 2:51one percent silver nitrate in ethanol so
71. 2:55um the purpose of this is basically
72. 2:59when we're doing this particular
73. 3:00reaction what we're looking for is a
74. 3:02precipitate so
75. 3:03that precipitate is going to be
76. 3:07silver halides so remember from general
77. 3:09chemistry
78. 3:11silver chlorides over bromide are not
79. 3:13soluble
80. 3:15in water but they're also not going to
81. 3:17be soluble in our ethanol solution
82. 3:20and then this is going to be a driving
83. 3:22force right le chatelier's principle
84. 3:24uh if you have one of the products the
85. 3:26silver chloride
86. 3:28precipitating out it's going to drive
87. 3:29the reaction to the right okay
88. 3:32and then the same is actually going to
89. 3:34occur for that sn2 reaction so since we
90. 3:36have
91. 3:37um we're using sodium iodide which is
92. 3:40soluble
93. 3:41in acetone great our leaving groups will
94. 3:45be the chloride and the bromide
95. 3:46and sodium chloride and sodium bromide
96. 3:49are not soluble acetone so those will
97. 3:50form
98. 3:51a precipitate as well uh again driving
99. 3:54the reaction
100. 3:55forward okay um
101. 3:58and again um
102. 4:02this is what we're pretty much looking
103. 4:04for when we're trying to determine
104. 4:07if a reaction occurred so
105. 4:10remember the precipitates can look
106. 4:14different depending on what's going on
107. 4:16right so
108. 4:17um it could look the solution might just
109. 4:20get cloudy
110. 4:21the solution could form obvious chunks
111. 4:25or it might just get it just
112. 4:28it just depends like um the precipitate
113. 4:31in other words is going to look
114. 4:32different
115. 4:32it's going to present itself differently
116. 4:34so we just need to make sure that when
117. 4:36we're doing these reactions
118. 4:38we make the best observations and notes
119. 4:40as possible so
120. 4:42we're where what i want you to do
121. 4:44throughout this video
122. 4:45is literally write down anything and
123. 4:47everything that you see
124. 4:48whether it's a color change if it's a
125. 4:50color change i i might mention that to
126. 4:52you
127. 4:54because it might be a little bit
128. 4:55difficult to identify that color change
129. 4:58or at least observe it in the video um
130. 5:01but and then if there's a precipitate or
131. 5:03cloudiness or whatever what i'm going to
132. 5:04do is just kind of
133. 5:06hold up the
134. 5:09test tube like that so that it's visible
135. 5:11to you
136. 5:12and so that way you can make your
137. 5:13observations um
138. 5:15so what we're going to do first is the
139. 5:18sn2 condition so
140. 5:20what i've actually done is uh set up
141. 5:25ten test tubes right here and you can
142. 5:28see that i've labeled them
143. 5:30numbers one through ten so here's our
144. 5:32five for you
145. 5:33uh i labeled them with a sharpie because
146. 5:36um
147. 5:38it doesn't come off very easily it does
148. 5:39come off you can hit it with some
149. 5:41isopropanol or
150. 5:42rubbing alcohol or acetone or whatever
151. 5:44when you're cleaning your dishes and
152. 5:46it'll come off
153. 5:48but we may or may not be placing these
154. 5:50test tubes in the water and so i just
155. 5:52don't want to i just want to make sure
156. 5:53it doesn't wipe off
157. 5:54okay so what i did here was i placed two
158. 5:58mills
159. 5:58of 15 sodium iodide
160. 6:02in acetone and so our nucleophile
161. 6:06is in here as well as our polar protic
162. 6:10sorry polar aprotic solvent and what
163. 6:12we're going to do is just add four drops
164. 6:14of let's say our substrates so
165. 6:18this first one that i'm gonna do is two
166. 6:20chlorobutane
167. 6:22uh it is a flammable liquid so obviously
168. 6:24we wanna be careful but
169. 6:26um just four drops and then we're going
170. 6:29to make our observations
171. 6:31so if nothing happens maybe
172. 6:35like after 30 seconds to a minute
173. 6:38then what we want to do is
174. 6:42obviously record those observations and
175. 6:45set that aside and then once we've done
176. 6:48all one through ten
177. 6:50and we've set aside the ones that don't
178. 6:53react after about a minute
179. 6:55and then we've set aside the ones that
180. 6:57do react we've separated them
181. 6:59and so the ones that don't react what
182. 7:01we're going to want to do is place those
183. 7:03in a 50 degree water bath and
184. 7:07of course higher temperatures is going
185. 7:09to allow us to uh
186. 7:10overcome the activation energy if it's
187. 7:12higher right
188. 7:15and so we want to see if the reaction
189. 7:18occurs
190. 7:18after placing it in a water bath and
191. 7:20then obviously record the approximate
192. 7:22time it takes for the reaction to occur
193. 7:24um or and how or if it didn't occur at
194. 7:28all okay
195. 7:29so literally literally write down
196. 7:31anything and everything you see and i'll
197. 7:33try my best to
198. 7:34kind of get the video on all the action
199. 7:37okay tons of action today so
200. 7:41um again putting just four drops of
201. 7:45uh two chlorobutane in the first one
202. 7:47looking at it swirling it we're going to
203. 7:49record our observations
204. 7:51let's say a precipitate did occur then
205. 7:53we're going to want to record
206. 7:54that uh in approximately how long it
207. 7:57took
208. 7:58and then um after that
209. 8:01we're gonna set that aside right that
210. 8:03reaction is done
211. 8:04and um and then well let's just let's
212. 8:07just go
213. 8:08let's go we got this you got it so
214. 8:13this first one right here oh and i do
215. 8:16want to mention that i
216. 8:17already set up that water bath because
217. 8:19i'm an adult on a plan ahead
218. 8:21because you don't want to get to the
219. 8:22point where you need to
220. 8:24use the water bath and then wait for it
221. 8:27to warm up right so all right so
222. 8:30here's the test tube number one
223. 8:34which is two chlorobutane okay
224. 8:38one two three
225. 8:41four
226. 8:44drops
227. 8:47now what you want to do when we're
228. 8:49actually performing these reactions
229. 8:51is approximate uh or
230. 8:54you decide if the reaction is going to
231. 8:56occur or not
232. 8:58um with or without heat doesn't matter
233. 9:00on paper is the reaction going to occur
234. 9:02and so of course you're taking into
235. 9:04consideration the
236. 9:06um the
237. 9:09substrate and then whether or not that's
238. 9:11likely going to occur
239. 9:12in an sn2 reaction in this case
240. 9:16and if it does
241. 9:19let's say like methyl and primary those
242. 9:22occur much faster than
243. 9:23secondary right and so when we're
244. 9:25recording our approximate time on how
245. 9:27long this took
246. 9:28then we also want to see if it goes
247. 9:30along with that trend as well
248. 9:31okay so we're applying everything we
249. 9:33know about sn2
250. 9:35into these ten reactions right here okay
251. 9:38so so far this is two chlorobutane
252. 9:42and
253. 9:47i'm not i'm just gonna tell you
254. 9:51i personally do not observe
255. 9:54a color change okay so
256. 9:58set that one aside for now now what we
257. 10:00want to do
258. 10:01is the next one is number two is
259. 10:05two bromo butane
260. 10:09overall let's see
261. 10:13so same structure
262. 10:17different leaving group right
263. 10:21hit that with four drops one two three
264. 10:23four
265. 10:24whoa that came out fast
266. 10:47[Music]
267. 10:56all right so next one okay so number
268. 11:01three here number three is going to be
269. 11:06one chlorobutane
270. 11:09okay so
271. 11:13we've got one two
272. 11:17three four drops
273. 11:35okay
274. 11:40just keep an eye on that for a little
275. 11:42longer
276. 11:46all right so um
277. 11:49set that aside for now
278. 11:53now the next one
279. 11:56is what do you think it is
280. 12:01one brobo butane number four
281. 12:04okay
282. 12:09okay okay no one
283. 12:12two three four
284. 12:20can't tell this one looks a little bit
285. 12:23more yellow
286. 12:25but it is difficult to tell
287. 12:29let's hold them all up together this is
288. 12:32uh
289. 12:32one on this side this is four on this
290. 12:35side so you can kind of see the
291. 12:36difference in
292. 12:38color um though oddly enough
293. 12:41the first two were actually the first
294. 12:43two substrates are yellow but the second
295. 12:45two were
296. 12:46colorless but it looks like the first
297. 12:49two
298. 12:50reactions are colorless and second two
299. 12:54are uh yellow so
300. 12:57again just in observations so uh
301. 13:01here we go now what we've got
302. 13:04is number five which is
303. 13:08tert butyl chloride also known
304. 13:11as two chloro uh
305. 13:14two methyl propane okay
306. 13:18two chloro two methyl propane yes
307. 13:22so aka tert butyl chloride it's
308. 13:26very similar in structure to the
309. 13:28terpetoxide remember that's the chicken
310. 13:30foot
311. 13:33one two three four
312. 13:42and boom boom boom boom
313. 13:51so this one is a little cloudy that's
314. 13:54the
315. 13:55the bromine one i'm sorry that number
316. 13:58that's number four that was one bromo
317. 14:00uh butane that is
318. 14:05looking body right
319. 14:10okay so um
320. 14:13let's see here what we've got is number
321. 14:16six
322. 14:18and this is crotal chloride okay
323. 14:42four
324. 14:48what you think
325. 14:51write it down
326. 15:02[Music]
327. 15:07all right number seven
328. 15:12chloride we got benzorad in the house yo
329. 15:18let's see what it does what it is what
330. 15:21it isn't
331. 15:24sorry hold up wait a minute
332. 15:28let me get my caps up in it
333. 15:31all right sorry i had to get myself
334. 15:33situated
335. 15:34benzo chloride
336. 15:38super cool super cool
337. 15:41one two three four
338. 15:45i'm going again just because i can
339. 15:51that's whoa
340. 15:55swirly swirly swirl
341. 16:07all right i think you've
342. 16:10had about enough of that one
343. 16:13all right so here's the number eight
344. 16:15this is bromo
345. 16:17benzene b romo benzene
346. 16:25b bromo frenzy
347. 16:29one two three four
348. 16:34fifth
349. 16:44here we go
350. 16:48while we're on the topic of one two
351. 16:50three four fifths
352. 16:54uh dave chappelle fantastic comedian
353. 16:57right
354. 16:58amazing um he was on
355. 17:01that netflix show with david letterman
356. 17:04um
357. 17:05forget what it's called uh but i'm sure
358. 17:08it's super easy to find if you have
359. 17:10netflix
360. 17:11check it out super cool loved it
361. 17:14liked it wanted some more of it
362. 17:18and then uh next so
363. 17:22we already kind of saw that right so
364. 17:24hopefully you're multitasking as i
365. 17:26am the next one number nine is
366. 17:29bromocyclohexane
367. 17:30okay
368. 17:38bro cycle hexane one two
369. 17:41three four five
370. 17:59my my hand looks like it's all swollen
371. 18:05like the incred like it got stung by
372. 18:09an alien really because what kind of
373. 18:11swollen
374. 18:12hand is that that's crazy y'all are
375. 18:14ridiculous right now
376. 18:16yeah they're just silly okay so bromo
377. 18:20cyclopentane
378. 18:21that last one number nine let's cycle
379. 18:23chromocyclohexane
380. 18:25this one right here is almost like a
381. 18:27little pantene
382. 18:31one two three four five ish
383. 18:54hmm
384. 18:59let's see if i can get that to
385. 19:02focus focus
386. 19:05from opening all right so
387. 19:09here's the thing i'm gonna run it back
388. 19:11one more time
389. 19:13so
390. 19:17here's one two three seemingly
391. 19:21you know no precipitation so i'm gonna
392. 19:23set those aside
393. 19:26here's number four so
394. 19:29number four hopefully you guys wrote
395. 19:31this down but it's a one
396. 19:32bromobutane do you think that looks like
397. 19:35a precipitate
398. 19:36okay cool so do i number five
399. 19:42it doesn't look like anything i'm gonna
400. 19:44go ahead and set that to the side number
401. 19:45six
402. 19:46which is protochloride that looks like
403. 19:49chunky not really chunky but it looks
404. 19:52like some
405. 19:54thick juice actually kind of delicious
406. 19:58number seven
407. 19:59that's benzoyl chloride that looks like
408. 20:02some
409. 20:03thick uh juice here's number eight
410. 20:07that's bromobenzene
411. 20:11number nine samesies
412. 20:14zoomzees nothing going on
413. 20:19number 10 so number nine and 10 with
414. 20:22bromocyclohexane
415. 20:23and bromocyclopentane respectively now
416. 20:26okay so what we've got here is
417. 20:31failure to react so what we're going to
418. 20:34do is
419. 20:34throw these inside of
420. 20:37my water bath which totally got set up
421. 20:40right now so let me show you
422. 20:41as i move that camera real quick so
423. 20:44what i'm likely going to have to do so
424. 20:46that you can actually like
425. 20:48observe closely is i'm going to hold the
426. 20:50camera so i'm sorry
427. 20:52i forgot shaky hands quick
428. 20:55um and but basically the only ones that
429. 20:58aren't
430. 20:59going to go in the water bath are number
431. 21:02four six and seven so um
432. 21:06yeah it's gonna look a little
433. 21:07complicated but uh
434. 21:10let's take a look all right so that
435. 21:14oh you can't see that very well that
436. 21:16says 48 that's good enough we got a hot
437. 21:18water bath going on right here i put it
438. 21:20in a beaker
439. 21:21uh specifically so that i could just go
440. 21:23like
441. 21:24what's up number nine engine engine
442. 21:28number nine set you in there
443. 21:31and then i would just kind of start the
444. 21:33clock you know what i mean so
445. 21:34let's go ahead and get everybody in
446. 21:36there we're gonna so that's what i meant
447. 21:38i meant i said complicated
448. 21:40oh i guess what i really meant was
449. 21:41crowded it's going to get crowded
450. 21:44in there and we're going to have to just
451. 21:46kind of keep an eye on
452. 21:48the individuals that
453. 21:51kind of form that precipitate so what
454. 21:53i'm going to do is kind of circle around
455. 21:58take a look see what about this one
456. 22:00right here
457. 22:02looks like maybe a little something
458. 22:05it looks kind of pretty though i'm not
459. 22:06gonna lie
460. 22:09um and then yeah
461. 22:14so let's keep it
462. 22:17keep it going so
463. 22:20ideally we wouldn't have the the
464. 22:24tubes necessarily sitting right on the
465. 22:26bottom of the beaker because it's
466. 22:28it's like it's sitting on the hot plate
467. 22:30but um it's not really
468. 22:32close not really touching it too much uh
469. 22:34and also it's only like 50 degrees so
470. 22:37it's not too hot
471. 22:39but keep that in mind and so i think
472. 22:42when i
473. 22:43[Music]
474. 22:44i don't know i think i misspoke ever in
475. 22:47the beginning
476. 22:48uh we kind of wanted to keep an eye on
477. 22:50this things at room temperature after
478. 22:51three minutes
479. 22:52to see if we had a reaction and so
480. 22:56what we're looking for is
481. 22:59uh essentially we're going to classify
482. 23:01in terms of rates of reactivity right
483. 23:04and so the things that were fast the
484. 23:07things that were slow
485. 23:08so um think about it like that if it
486. 23:11occurred
487. 23:15so the the reactive halides for example
488. 23:18give a precipitate within three minutes
489. 23:20at room temperature
490. 23:21the moderately reactive halides would
491. 23:24give a precipitate when heated
492. 23:26and the unreactive halides do not give a
493. 23:28precipitate
494. 23:29okay even when heated so we want to
495. 23:31record those results in our notebook
496. 23:33or and then explain why the compound
497. 23:38has their activity you observe and then
498. 23:40whether or not you it kind of matches
499. 23:42your prediction that i told you to make
500. 23:44in the beginning
501. 23:48so i'm gonna go ahead and say that this
502. 23:51this one right
503. 23:52here this
504. 24:01yeah just another
505. 24:05minute or so
506. 24:10and then we'll take them all out let
507. 24:11them cool room temperature and then
508. 24:13we'll see
509. 24:14what they've got
510. 24:29okay so that was definitely plenty of
511. 24:31time
512. 24:32so we're going to do is take these bad
513. 24:34boys out
514. 24:37one thing i also want to note that is we
515. 24:40heat it to like why did we only hit 250.
516. 24:43well first of all remember that when you
517. 24:46heat
518. 24:47uh a reaction in general uh any increase
519. 24:50in about 10 degrees is approximately
520. 24:54doubling the rate of the reaction
521. 24:56right super cool uh fun little
522. 24:59fact about that but in addition to that
523. 25:02what we have
524. 25:02is uh a solvent that does boil
525. 25:06around there so we don't want to go
526. 25:07higher than the solvent's boiling point
527. 25:10when we're heating it
528. 25:10so that's something you want to keep in
529. 25:12mind whenever you're doing a chemical
530. 25:13reaction
531. 25:14if the reaction doesn't doesn't occur at
532. 25:17room temperature and you want to
533. 25:18increase the temperature
534. 25:20uh is it going to require a lot
535. 25:23if it requires a lot then you're
536. 25:25probably going to want to choose a
537. 25:26solvent that has a high boiling point
538. 25:28so for example like toluene is
539. 25:31it's um it's like a benzene ring with
540. 25:34the methyl on it
541. 25:35that has a boiling point of 110 degrees
542. 25:37so if i wanted to like keep the heck out
543. 25:39of these then
544. 25:40i might choose that one okay so uh not
545. 25:43super polar though so it's not an ideal
546. 25:45reaction
547. 25:46solvent for uh sn2 but
548. 25:50let's take a look at these ones and see
549. 25:51what kind of precipitate we've got
550. 25:54okay so i'm not gonna say anything i
551. 25:57just kind of want you guys to figure
552. 25:58this out
553. 25:59okay so all i'm gonna say is
554. 26:03number one one
555. 26:06one one his number two
556. 26:10two two his number two
557. 26:14and three three three his number three
558. 26:21[Music]
559. 26:23i girl like that too uh here's number
560. 26:26five
561. 26:27[Music]
562. 26:30that's what's up here's number eight
563. 26:34okay and here's number
564. 26:48snow globin what's up snow globin
565. 26:52uh and there you have it so go ahead
566. 26:56write it down take a picture
567. 27:00think about it um i encourage you to
568. 27:06not only draw your structures out but
569. 27:09classify them according to alkyl halide
570. 27:12so like methyl primary secondary
571. 27:15tertiary
572. 27:16um or like benzyl if it or it's uh
573. 27:20allylic or vinylic or ariel
574. 27:23etc okay so watch the videos the lecture
575. 27:26videos
576. 27:27if you don't remember the rates of
577. 27:29general rates of reactivity it's really
578. 27:31important that you do
579. 27:32um and then hopefully we observed that
580. 27:37trend
581. 27:37here in the left if not maybe i made an
582. 27:40error
583. 27:40maybe not maybe you're not thinking
584. 27:43about it right maybe
585. 27:44maybe maybe maybe right think about it
586. 27:48super fun stuff so now what i got to do
587. 27:51is clean out these test tubes and then
588. 27:54what we're going to do
589. 27:55is the sn1 reaction same exact thing so
590. 27:59hopefully we can just run through it a
591. 28:01lot quicker this time
592. 28:03and then um
593. 28:07yeah get on our way right so uh one
594. 28:10thing i will say is that
595. 28:12this particular it's an sn1 reaction
596. 28:16there's a little bit of water that's
597. 28:18gonna be in here uh in the ethanol
598. 28:21it is supposed to be absolute ethanol
599. 28:22but um
600. 28:25what i'm getting at is i'm gonna clean
601. 28:27these and i'm not gonna get too crazy
602. 28:29about drying them
603. 28:30i'm just going to try i'm just going to
604. 28:31wash them flip them upside down and then
605. 28:33do some other stuff for real quick and
606. 28:35then be on my way okay
607. 28:37just to be able to move quickly because
608. 28:40this is an sn1 reaction
609. 28:41water is a polar protic solvent and so
610. 28:44like it's not going to be the end of the
611. 28:45world if
612. 28:46they're a little bit in there silver
613. 28:48chloride or bromide are still going to
614. 28:50precipitate perfectly fine in water so
615. 28:52it shouldn't affect
616. 28:53the rate of the reaction uh yada yada
617. 28:56okay
618. 29:01all right so the relative reactivity
619. 29:03over the yeas of some alkyl halides
620. 29:05um these are the ten substrates in order
621. 29:08uh going from top to bottom on the left
622. 29:11and then going
623. 29:12from top to bottom on the right so um
624. 29:15two chlorobutane there's a structure two
625. 29:17bromobutane there's a structure
626. 29:19uh one chloro and one bromobutane
627. 29:22structure's right there
628. 29:24two chloro2 methyl propane aka butyl
629. 29:27chloride now those are all flammable
630. 29:30liquids okay
631. 29:31so they're they're hydrocarbons right so
632. 29:33um
633. 29:34crotochloride on the upper right as well
634. 29:36as benzyl chloride those are called
635. 29:38lacromators and lacrimators are actually
636. 29:43here let me write that down for you
637. 29:46lac rimmatore
638. 29:53and that's benzoyl chloride as well as
639. 29:55crotal chloride these
640. 29:56are lacquer maters because um
641. 30:00they irritate your eyes and they can
642. 30:02cause
643. 30:03tears and so that is
644. 30:06why they're called lacrimaters and this
645. 30:08is one of the
646. 30:09hazards that you want to write down in
647. 30:12your table
648. 30:13um now bromobenzene and bromocyclohexane
649. 30:17and bravocyclopentane those are also
650. 30:20going to be flammable liquids as well
651. 30:26and where any time you're in a lab you
652. 30:29always want to just assume everything's
653. 30:31toxic
654. 30:33and everything's flammable and
655. 30:34everything's dangerous and so that's
656. 30:36what we're going to do here okay so
657. 30:38all these are toxic uh and flammable and
658. 30:41i also want to add in that lacrimator
659. 30:43just for uh kind of some vocabulary
660. 30:47in terms of some hazards that we need to
661. 30:49be aware of
662. 30:50and there you go so let's go ahead and
663. 30:53start the reaction
664. 30:56all right so uh just a reminder
665. 30:59for the sn1 as well to listen to
666. 31:03we want to make sure that we're thinking
667. 31:04about the structure of these substrates
668. 31:06because the nucleophile is the same the
669. 31:08solvent's the same and identifying the
670. 31:11reason why a reaction would occur
671. 31:13faster or slower and then we're going to
672. 31:15rank these
673. 31:16according to high reactivity or mild
674. 31:20or moderate mildly moderate
675. 31:23being the same and then also
676. 31:26non-reactive alkyl halides
677. 31:29and so in addition to that i want you to
678. 31:32think about
679. 31:33um like i said the alkyl halide the
680. 31:37was it like was it tertiary or secondary
681. 31:40etc
682. 31:41you also want to think about
683. 31:45the structure of the compound um
684. 31:48for example is there any particular
685. 31:50strain in it already
686. 31:52uh that's and then how that strain might
687. 31:54affect the rate of reactivity
688. 31:56uh in terms of bond strengths etc so um
689. 32:00that's kind of just some guidance and uh
690. 32:04and moving forward for this particular
691. 32:06reaction
692. 32:09and so now what we want to do is we're
693. 32:12going to
694. 32:12[Music]
695. 32:14do the sn1 reaction conditions so we're
696. 32:17using all of the same substrates so
697. 32:19compound 1 through 10 in the same order
698. 32:21again
699. 32:23but this time what i have here is a
700. 32:25solution of
701. 32:26silver nitrate in here and
702. 32:30again this is a one percent silver
703. 32:32nitrate in
704. 32:33ethanol solution so this is
705. 32:36the polar protic solvent so that's going
706. 32:38to promote sn1
707. 32:41and then we also have so i have a number
708. 32:44one right here
709. 32:45and then this is number six and so when
710. 32:47it comes time
711. 32:48i'll put the ones that are in the back
712. 32:50seven eight nine ten
713. 32:51uh we'll rotate this rack so that you
714. 32:53have a better look at them but what i
715. 32:55really want to do is just kind of
716. 32:56quickly add the substrates to all of
717. 32:59these
718. 32:59and then let you take a look at them for
719. 33:02a bit
720. 33:03and then we'll kind of rotate this
721. 33:04around
722. 33:06boom like that and then we'll move on
723. 33:08okay so
724. 33:12let's see was there anything else that i
725. 33:15wanted to add
726. 33:18no i don't think so
727. 33:22so uh oh there was also leaving groups
728. 33:25that i wanted to
729. 33:26see if you uh kind of paid attention to
730. 33:30in terms of
731. 33:31uh classifying the rate of reactivity
732. 33:33okay so
733. 33:34now what we're going to do is quickly
734. 33:37and carefully move through
735. 33:42these reactions okay so sorry i'm
736. 33:44getting organized moments
737. 33:46i'm going to change things all right
738. 33:48again this is number one
739. 33:50so i'm gonna add four drops to it you
740. 33:52keep an eye on it
741. 33:54so let's see this is two chlorobutane
742. 33:57one two three four
743. 34:03and we're gonna give it a little shaky
744. 34:05shake
745. 34:0666666 okay
746. 34:10now we're doing two bromobutane
747. 34:15one two three four ish
748. 34:22a little shaky shake wait you can't see
749. 34:24that
750. 34:25little shaky shake okay okay though
751. 34:32now number three is one chlorobutane
752. 34:38one two three fourish
753. 34:48there it is one bromobutane for number
754. 34:52four
755. 35:00shaky shake
756. 35:06what you know about sn2
757. 35:10or sn1 alright so this is
758. 35:14number five
759. 35:17we got that t-butyl chloride
760. 35:42so benzyl chloride well before we move
761. 35:45on to benzyl chloride
762. 35:47because that's the number seven that's
763. 35:49on the back
764. 35:51we're gonna go ahead and take a look at
765. 35:52this again a little shaky shake
766. 35:54okay this is number two
767. 35:58here's number three a little shaky shake
768. 36:09number four okay
769. 36:16and then number five number six
770. 36:19all right so we'll probably take a look
771. 36:21at these when we come back
772. 36:24uh right before we start adding things
773. 36:26to the heat
774. 36:27but here's number seven eight nine
775. 36:30and ten number seven
776. 36:34is benzoyl chloride
777. 36:38what you think one two three
778. 36:52four-ish
779. 37:10eight bromobenzene
780. 37:32it's got doing something silly over here
781. 37:34oh it's because it's dripping down
782. 37:36t
783. 37:43bromocyclohexane
784. 37:46number nine
785. 37:49that was probably too many drops but
786. 37:51don't worry about it folks
787. 37:54don't even worry about it
788. 37:58it's okay you're gonna be all right
789. 38:04it's okay probably cyclopentane
790. 38:07let's see what it does
791. 38:10one two three four five
792. 38:15one two whoa simmer down there
793. 38:19bromocyclopentane you got an
794. 38:22attitude coming in hot huh
795. 38:25let's see what what it is what it look
796. 38:28like
797. 38:29okay it's so chunky
798. 38:40that's number eight so seven nine and
799. 38:42ten are
800. 38:43straight up killing that precipitate
801. 38:45game what do you think
802. 38:47i think they are number one
803. 38:51i mean he could try harder but
804. 38:55there's something going on there i don't
805. 38:56know what's going on there
806. 39:00let's see number two clearly
807. 39:04number three let's see number one and
808. 39:07number three
809. 39:09two chlorobutane and then one
810. 39:11chlorobutane so
811. 39:14um let's see if we can go ahead and take
812. 39:17these guys for a little
813. 39:19ticket for a little stroll take a little
814. 39:22bath
815. 39:23same z's with number eight okay
816. 39:27i'll see you all over there
817. 39:31okay it's been in there literally five
818. 39:33seconds i just had to
819. 39:35put them in there and then grab the
820. 39:38camera
821. 39:40leave them in there for a hot minute and
822. 39:42then we'll take a look-see
823. 39:44looks like there's something going on in
824. 39:46there though i don't know about you
825. 39:48it looks kind of cool like glowing
826. 39:53let's see what is it called like arrow
827. 39:56gel
828. 39:57something like that they basically
829. 40:03we'll talk about that another day it's
830. 40:04cool stuff though but
831. 40:06a little something going on perhaps
832. 40:10yes i'm at 42 seconds
833. 40:13on my clock so i'm gonna
834. 40:18yeah we're gonna hang out for another 10
835. 40:19seconds how about this
836. 40:22um don't forget that this silver nitrate
837. 40:26is added just to kind of allow
838. 40:28precipitate to form so that it's obvious
839. 40:31that the reaction did move forward
840. 40:32it's also going to help drive that
841. 40:34reaction forward once that
842. 40:36leaving group leaves is gone because it
843. 40:39precipitated out as silver
844. 40:40chloride or silver bromide and
845. 40:44there you have it folks so i'm gonna
846. 40:46take these out and we'll let them cool
847. 40:47to room temperature we'll take a little
848. 40:48look-see okay
849. 40:51all right so there's number one three
850. 40:54and eight
851. 40:55from left to right one three eight and
852. 40:58there's
853. 41:00record your results so so i don't want
854. 41:02you to
855. 41:04um i don't want you to think that
856. 41:09i don't know what i'm saying so
857. 41:12let's see if you see a reaction that
858. 41:17does move forward and you don't think it
859. 41:19should then trust your instincts
860. 41:21okay so that means there might have been
861. 41:23an error right
862. 41:24um but also
863. 41:28you kind of do want to question your
864. 41:29instincts a little bit sometimes so
865. 41:31provided you have studied sn1 and sn2
866. 41:34reactions
867. 41:35and you're confident with that then and
868. 41:38you see the reaction move forward then
869. 41:39and it contradicts what you've learned
870. 41:42then
871. 41:43what you should look carefully at the
872. 41:45possibilities of
873. 41:48error associated with either something i
874. 41:51did
875. 41:51or things that were even out of my hand
876. 41:54so for example i got these from
877. 41:56the stockroom they're already made these
878. 41:59substrates as well as these solvents and
879. 42:01the nucleophile already prepped and so
880. 42:04who's to say what they really are and
881. 42:06now i wouldn't want to say that
882. 42:08they are what they are but how clean are
883. 42:11they
884. 42:11is there any source of contamination and
885. 42:14i don't want you to just cut
886. 42:16like that's the cop out if you just say
887. 42:17yeah i was contaminated that's why
888. 42:19that's why i moved forward and it
889. 42:21shouldn't have no
890. 42:23um that's a reason possibly
891. 42:27but i won't read one reason i want
892. 42:28multiple reasons i want any and all
893. 42:30reasons that you can possibly think of
894. 42:32and i want specifics i don't want to
895. 42:33just say i don't want you to say
896. 42:35it was human error or no stop it that's
897. 42:38ridiculous
898. 42:39because you could just say that for
899. 42:41everything right
900. 42:43oh it didn't work out because of human
901. 42:44error well that's not critical thinking
902. 42:47and we really want to critically think
903. 42:48about
904. 42:49the sn1 and sn2 reactions that we've
905. 42:51done in the lab right now
906. 42:53and especially since you're not even
907. 42:54here to do it yourself you
908. 42:56need to get the best out of this process
909. 42:58so
910. 42:59you need to critically think about why
911. 43:03some reactions went forward faster than
912. 43:05others why
913. 43:06they went slower why they didn't go at
914. 43:09all
915. 43:09why they went forward and they probably
916. 43:11shouldn't have or
917. 43:13why they should have gone forward but
918. 43:15they didn't go forward so any
919. 43:17possibilities that may have occurred i'm
920. 43:18not saying that
921. 43:19any of those are applicable here other
922. 43:22than the obvious but
923. 43:24i'm just trying to say you got to think
924. 43:28so uh yeah
925. 43:34i think that's it yo i'm going to go
926. 43:36ahead and clean up
927. 43:37throw my stuff in the proper waste
928. 43:38container
929. 43:41and then what do you think i'm gonna get
930. 43:46a red bull