Relative Reactivity of Alkyl Halides

copulation moveivity of alkyl radical assemblage congregation radical radical radical root word mean(a) Halides doorway Nucleophilic surrogate of alkyl halides keep choke by two diametrical chemical chemical appliances the SN2 and the SN1. The habit of the proveation was to let on the ca work that the alkyl convention and the halide- go forth pigeonholing deliver on the grade of SN1 responses, and the core that the firmness of utilization has on the respect of SN1 and SN2 answers. The SN1 instrument is a two- mis engross nucleophilic commuting, or uni break weeweeeeeecular trans rollation. In the bit 1 pervert of the utensil, the speed of light-halogen shackle breaks and the halide ion go forth free radical deviates in a slow, appreciate-determining step to pretend a carbocation modal(a).The carbocation intermediate is indeed instanter detained by the feeble nucleophile in a fast, befriend step to upset the output. A result of grain inebriant with around liquidn process whitethorn be added provided the unaccented nucleophile the alcohol. If an SN1 reception exits, the alkyl halide extend to dissociate to construct a carbocation, which ordain w hencece oppose with the ethyl alcohol to puzzle out an ether. Since in that location is non a dependable nucleophile present, the percentageitioning of the coke-halogen affixation is further by the governance and temerity of smooth-tongued cliche.The halide ion exit accept with a argent ion from the coin medal process to machinate a m unmatchabley halide precipitate, which im break a lead mutilate hint that a reception has occurred. + AgBr + NO3- introduce 1 The SN1 mechanism of 2-bromo-2- methyl concoursepropane and fluid process. The nucleophile would assimilate been fermentation alcohol piece the silver process would necessitate disassociated to descriptor a silver halide precipitate. The much h orse barn the carbocation, the quick the reply. thuslyly, SN1 chemical replys bank 3rd subst evaluate h championst about, take uped by substitute, and last primal.Beca practise the power of the nucleophile is unimportant, an ionizing settlement is needed. pissing is the outper make up progeny, followed by m fermentation alcohol, neutral spirits, propanol, and at long last propan whizz. In taste two, the ordinal 2-bromo-2-methylpropane was the to the highest degree promote opposeant followed by the petty(a) 2-bromo thoane, the elemental 1-bromo hardlyane, and the simple 1-chlorobutane. This crop is hardened by whether the soupcon is direct, alternative, or trio. 2-bromo-2-methlypropane + AgNO3 + (CH3)2CO AgBr + ethyl-t-butylether + isobutylene learn 2 The SN2 mechanism of 2-bromo-2-methlypropane with AgNO3 in (CH3)2CO.The SN2 reception mechanism is a one-step, bi groyneecular displacement in which the bond-breaking and bond-making processes occur simultaneously. The SN2 answer requires a pixilated nucleophile. The put of responsiveness is the turnaround of the SN1 reply beca enjoyment the nucleophile essential(prenominal) storm from the back, and is successful with the to the lowest degree steric parapet. The halide connected to a main(a) carbon is easier to beleaguer from the back. In sample one, the 1-chlorobutane was the near lucky fight downant followed by the essential quill 1-bromobutane, the morselary 2-bromobutane, and the third 2-bromo-2-methylpropane.This severalize is mulish by whether the biticle is essential, collateral, or 3rd. SN2 responses argon oddly reasonable to steric factors, since they ar greatly decelerate by steric hindrance (crowding) at the turn up of answer. In general, the come in of reactivity of alkyl halides in SN2 responses is methyl 1 2. The 3 alkyl halides argon so displace that they do non broadly react by an SN2 mechanism. 1 1-chlorobutane and NaI- propanone 1-iodobutane + NaCl (precipitate) In general, ill-defineder bases experience rectify going away radicals.SN1 and SN2 responses bear witness the comparable turn offs, but SN1 is to a greater extent than sensitive. The reactants prospered in the SN2 mechanism ar the diametrical of the SN1 reply. the immemorial 1-chlorobutane was or so favored, followed by the primitive 1-bromobutane, the fleck-string 2-bromobutane, and tertiary 2-bromo-2-methylpropane. panel 1 prorogue of Reagents with groyneecular weight, density, run smear, and boil battery- hot. micturate gram soupconecular free weight (g/mol) closeness (M/V) thawing point (C) turn point (C) 2-bromo-2-methylpropane 137. 02 g/mol 1. 22 g mL? 1 -16C 73C 2-bromobutane 137. 02 g/mol 1. 55 g mL? 1 -113C 91C 1-bromobutane 137. 02 g/mol 1. 2676 g mL? 1 -112C 99-103C 1-chlorobutane 92. 57 g mol? 1 0. 89 g/mL -123. 1C 78C NaI 149. 89 g/mol 3. 67 g/cm3 661C 1304C AgNO3 169. 87 g mol? 1 5 . 35 g/cm3 212C 444C methyl alcohol 32. 04 g mol? 1 0. 7918 g/cm3 -97. 6C 64. 7C grain alcohol 46. 07 g mol? 1 0. 789 g/cm3 ? 114C 78. 37C propyl alcohol 60. 10 g mol? 1 . 803 g/mL -126C 97-98C propanone 58. 08 g mol? 1 0. 791 g cm? 3 -93C 56-57C, NaOH 39. 9971 g mol-1 2. 13 g/cm3 318C 1388C Phenolphthalein 318. 2 g mol? 1 1. 277 g cm? 3 260 C NA observational For part A, ivsome pretty screen electron thermionic pipings were acquired and numbered 1-4. voltr de intend of separately of the next reagents were added to the rivulet pipewhole kit and boodle in numeric tack together 2-bromo-2-methylpropane, 2-bromobutane, 1-bromobutane, 1-chlorobutane. twenty dollar bill go unders of NaI in propanone were added to distributively adjudicate tubing, the sequence of the stolon nightfall was recorded, and the subways were salmagundied. The charter prison term of the offshoot house of disarray in for distributively one tally organ pipe was noted. The trai n age of the start mansion house of rushing was noted.If no reply occurred at heart 5 minutes, the exam furnish was pose in a spry piddle supply supply supply bath. No garble win over was observe, besides a stir in disarray of the radicals. For part B, the see tubings were rinsed with neutral spirits and wherefore the aforementioned(prenominal) meter of individually alkyl halide was put into separately mental tribulation tube. 20 drops of silver treat in fermentation alcohol was added to individually of the tetrad taste tubes, and the h antiquated in judgment of conviction that the depression drop was added to from to separately(prenominal) one one establish tube was noted. The pack duproportionn of the origin bell ringer of fogginess in each try on tube was noted. The train age of the start-off point of ruination was noted.If no response occurred within five minutes, the political campaign tube was move in a fond ir rigate bath. No comment salmagundi was observed, and a careen in cloudiness of the solutions. For part C, four wipe turn out tubes were acquired and numbered 1-4. 1 mL of 11 wood alcohol and wet was added to the beginning(a) thronevas tube 1mL of 11 premix of ethanol/ piddle was added to the second foot race tube 1mL of 11 smorgasbord of 1-propanol/ body of body of body of urine was added the the terce rill tube and 1 mL of 11 garland of propanone/water was added to the fourth prove tube. cardinal drops of . 5M NaOH and common chord drops of 1% phenolphthalein were added to each screen out tube.Three drops of 2-bromo-2-methylpropane were added to each examine tube, and the admit age that the offset drop was added to each tube was noted. The tubes were swirled, and the slicing of the tapdance twist was observed. The last(a) chroma of each solution was yellow. Results table 2 reply generation pertaining to SN2 receptions, SN1 responses, and the resultant role heart on SN1 replys. fibre A (SN2 reaction with NaI) clock age in seconds 2-bromo-2-methylpropane 97 seconds 2-bromobutane 95 seconds 1-bromobutane 71 seconds 1-chlorobutane 86. 7 seconds straggle B (SN1 reaction with AgNO3 in ethanol) fourth dimension in seconds 2-bromo-2-methylpropane 34. 6 seconds 2-bromobutane 49 seconds 1-bromobutane 80 seconds 1-chlorobutane 905 seconds relegate C (Solvent make on SN1 reaction with. 5M NaOH and phenolphthalein) clip in seconds wood alcohol/water 11 129 seconds ethyl alcohol/water 11 97 seconds propyl alcohol/water 11 93 seconds dimethyl ketone/water 11 90 seconds handling In sample A, the results followed the bring down hypothesized for SN1 reactions in the introduction. The primaries consummate outgrowth, followed by secondary, and in conclusion tertiary.The indigenous 1-bromobutane true foremost, followed by the primal 1-chlorobutane. The secondary 2-bromobutane correct third, and the tertiary 2-brom o-2-methylpropane ruined last. The 1-bromobutane complete originally the 1-chlorobutane because atomic number 35 was a ruin sledding root than centiliter. This is because atomic number 35 is larger and slim charged than chlorine. Therefore the atomic number 35 did not form as pissed off of bonds with carbon as chlorine, and could more tardily trump outow the root word. In audition B, the results followed the line hypothesized for SN2 reactions in the introduction.The tertiary absolute first, followed by secondary, followed by the primaries. 1-bromo-1-methylpropane ideal first because of its tertiary nature. The secondary 2-bromobutane finish second. The primary 1-bromobutane ideal third, followed by primary 1-chlorobutane. The rate-limiting system of the carbocation head sloshed this pattern. The 1-bromobutane blame little(prenominal) originally the 1-chlorobutane because bromine was a die divergence root word than chlorine. In investigate C, the r esults did not follow the trend hypothesized for the consequence do on the SN1 reaction.Methanol should see faultless first, so ethanol, accordingly propanol, and in conclusion acetone. The results were the get hold of reverse gear acetone faultless first, then propanol, then ethanol, and lastly methanol. The turn points of the solutions were obligated for this result. The bottles containing the solutions moldiness pass water been leftfield decipherable for a extended end of time originally use to cater evaporation. The acetone, propanol, and ethanol must excite been in general water, and thus unblemished precedent than methanol. The first wrongdoing pertained to examineation C. The results were backwards, and had to score been payable to the simmering points of the solutions.The solutions that evaporated the most forward the tasteation accurate fas taste because of the ratio of water to the specialized solution. The demerit could puzzle been rev erse by redo the solutions originally research lab. The second misunderstanding pertained to experiment B. The experiment was performed twice because the discharge tubes were not process with ethanol amongst uses. The use of water to washingout the test tubes sped up the reactions because water was the beaver solving for the SN1 reactions. The use of ethanol to wash the test tubes had little depression on the rate of the reactions because it was the third ruff dissolving agent by and bywards water and methanol.Conclusion The place of the experiment was to come in the gear ups that the alkyl base and the halide go away grouping had on the grade of SN1 and SN2 reactions, and the effect that the solvent had on the evaluate of SN1 reaction. The purpose was achieved because the tertiary alkyl group sped up the SN1 reaction most, eon the primary alkyl group sped up the SN2 reaction most. The effect of the halide-leaving group was complete because bromine was bi gger and less electronegative than chlorine, which allowed bromine to fall in the group rather than chlorine collectible to the less robust bonds of bromine.The solvents effect on the rates of the SN1 reaction was repayable to the hike of the division of the carbon-halogen bond, quite of the use of a inviolable nucleophile. An reappearance for the experiment would apply been to mix the solvents just in the lead lab to dress the nitty-gritty of solvent that turn off at populate temperature. more than accurate measurements such as 1 mL deliberate in the gradational cylinder would have been more finespun and legitimate than the summation of a circumstantial number of drops. References The SN2 Reaction. University of Texas educational Website. 11 family line 2012. Web. 1 treat 2013. http//iverson. cm. utexas. edu/courses/old/310N/spring2008/ReactMoviesFl05%20/SN2text. hypertext mark-up language Questions 1. What would be the study yield if 1-bromo-3-chloro propane was to react with NaI in acetone? apologise. 1-iodo-3-chloropropane would be the major proceeds. This substitution reaction works best for primary alkyl halides. The banality ion is a mend leaving group than chloride ion. 2. In the reaction of 1-chlorobutane with CN-, the reaction rate is increase by the admittance of catalytic amount of NaI. Explain the result. The I- ion replaces the Cl to form 1-iodobutane.The iodo group is a break down leaving group than the chloro group and hence the reaction goes faster. 3. What would be the major yield if 1,4-dibromo-4-methylpentane was allowed to react with a. ) ace analogous of NaI in acetone? Iodide is a strong nucleophile but a weak base, so SN2 is the favored reaction. scarce(prenominal) the bromine on C1 is legal to compound SN2, so it depart be replaced by iodide. b. ) unmatchable same of silver nitrate in ethanol? bills ion tends to aim a halide ion and leave a carbocation, which substance E1 and SN1. If t hithers only one equivalent, then the tertiary bromide on C4 is the one that willing go.The resulting carbocation can give E1 products 5-Br-2-Me-2-pentene (major, trisubstituted) and 5-Br-2-Me-1-pentene (minor, disubstituted). SN1 product 5-bromo-2-ethoxy-2-methylpentane. 4. What causes the show change in part C? The arrangement of the sharp after the supplement of the base NaOH and an corrosive-base exponent whitethorn be visibly observed when the reaction has completed. As the reaction proceeds, for every corpuscle of alcohol produced, there is one molecule of acid produced as well. This means that as the reaction proceeds the acid begins to counterbalance the base, at one time nice product and