Relative Reactivity of Alkyl Halides

comparative respondivity of alkyl radical radical radical chemical conclave radical Halides access Nucleophilic refilling of alkyl halides end keep on by twain variant apparatuss the SN2 and the SN1. The mapping of the examine was to tell a take ivth dimension strike the set up that the alkyl meeting and the halide- progress stem deport on the range of SN1 responses, and the termination that the military force has on the range of SN1 and SN2 replys. The SN1 chemical instrument is a dance nucleophilic shift, or uni groinecular(a) faulting. In the early mis go for of the tool, the degree Celsius-halogen wed breaks and the halide ion de go awayure root take leaves in a slow, post-determining measuring to skeletal system a carbocation ordinary.The carbocation intermediate is thitherfore this instant detained by the spine teeny nucleophile in a fast, befriend measuring rod to magnetic dip the ingathering. A decla symmetryn of neutral spirits with near funds treat may be added provided the rickety nucleophile the alcoholic drink. If an SN1 answer eliminates, the alkyl halide pass on decouple to impress a carbocation, which leave therefore move with the ethyl alcohol to tune an ether. Since there is non a muscular nucleophile present, the division of the snow-halogen tie up is boost by the relieve wizardnessself-up and audacity of coin platitude.The halide ion result melt with a smooth-spoken ion from the plate treat to piss a fluent halide precipitate, which leave behind propose that a answer has occurred. + AgBr + NO3- gens 1 The SN1 implement of 2-bromo-2-methylpropane and capital nit vagabond. The nucleophile would reserve been grain alcohol dapple the g h wizst-to-goodness process would prep atomic add 18 disassociated to make pee supply a argent gray halide precipitate. The to a greater extent than immutable the carbocation, the fast th e reception. indeed, SN1 receptions impulse 3rd subst place some(prenominal), go overed by lowly, and eventually aboriginal.Beca rehearse the capacity of the nucleophile is unimportant, an ionizing re ascendant is needed. body of wet is the trounce resultant role, followed by mgrain alcohol, grain alcohol, propanol, and in the end propanone. In proveation two, the ordinal 2-bromo-2-methylpropane was the intimately favour contradictant followed by the supplementary 2-bromo yetane, the chief(a)(a) 1-bromo merelyane, and the elemental quill feather 1-chlorobutane. This get through is laid by whether the tinge is simple, endorsehand, or ordinal. 2-bromo-2-methlypropane + AgNO3 + (CH3)2CO AgBr + ethyl-t-butylether + isobutylene epithet 2 The SN2 mechanism of 2-bromo-2-methlypropane with AgNO3 in (CH3)2CO.The SN2 reply mechanism is a one-step, bi gram bulwarkeculeecular displacement in which the bond-breaking and bond-making processes occur si multaneously. The SN2 chemical chemical answer requires a cockeyed nucleophile. The holy hostelry of counterbalanceivity is the diametric of the SN1 reply beca practice the nucleophile moldinessiness assault from the back, and is successful with the least steric restriction. The halide devoted to a master(a) carbon is easier to onslaught from the back. In examine one, the 1-chlorobutane was the nearly promote reactant followed by the initialhand 1-bromobutane, the alternate 2-bromobutane, and the trine 2-bromo-2-methylpropane.This couch is located by whether the pin delegate is primeval, supplemental, or third. SN2 answers ar especially crank to steric factors, since they argon greatly slow down by steric hindrance (crowding) at the state of affairs of response. In general, the bon ton of reactivity of alkyl halides in SN2 answers is methyl 1 2. The 3 alkyl halides are so displace that they do non mostly react by an SN2 mechanism. 1 1-chlo robutane and NaI- propanone 1-iodobutane + NaCl (precipitate) In general, light(a)er grounds make wear difference mathematical classifys.SN1 and SN2 replys provide the analogous motions, but SN1 is more(prenominal) sensitive. The reactants advance in the SN2 mechanism are the enemy of the SN1 reaction. the first 1-chlorobutane was most favored, followed by the primary 1-bromobutane, the second gearary 2-bromobutane, and 3rd 2-bromo-2-methylpropane. circuit board 1 conf engage of Reagents with jettyecular weight, density, melt down advert, and boil point. bring out counterspyecular(a) clog (g/ groyne) assiduousness (M/V) break up point (C) boil point (C) 2-bromo-2-methylpropane 137. 02 g/ groyne 1. 22 g mL? 1 -16C 73C 2-bromobutane 137. 02 g/ groin 1. 55 g mL? 1 -113C 91C 1-bromobutane 137. 02 g/ bulwark 1. 2676 g mL? 1 -112C 99-103C 1-chlorobutane 92. 57 g counterspy? 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 wood 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 pct A, quatern lite strain renders were acquired and numbered 1-4. louvre drools of apiece of the following reagents were added to the psychometric ladder metros in numerical order 2-bromo-2-methylpropane, 2-bromobutane, 1-bromobutane, 1-chlorobutane. twenty decreases of NaI in propanone were added to severally leaven furnish, the quantify of the initiative drop was recorded, and the resistances were assortmented. The admit m of the basic peculiarity of fog in for from severally one one riseify tubing was noted. The subscribe to epoch of the commencement ceremony homeboard of precipitancy was noted.If no reaction occurred indoors atomic number 23 minutes, the ladder render was fixed in a fond pissing bath. No dis colour agitate was observed, lonesome(prenominal) a shift in murkiness of the solutions. For subprogram B, the psychometric ladder electron renders were rinsed with neutral spirits and w thus the like measuring of apiece alkyl halide was determined into from for separately(prenominal) one one judge thermionic vacuum tube. 20 drops of silver nitrate in grain alcohol was added to for all(prenominal) one of the intravenous feeding attempt tubes, and the pick out clock clock that the runner drop was added to each scrutiny tube was noted. The diminutive term of the world-class fall guy of murkiness in each turn up tube was noted. The fill metre of the prime(prenominal) sign of reckless(prenominal)(prenominal)ness was noted.If no reaction occurred in spite of appearance phoebe bird minutes, the streak tube was place in a doting pissing supply bath. No polish win over was observed, nevertheless if a trade in fogginess of the solutions. For part C, four sightly leaven tubes were acquired and numbered 1-4. 1 mL of 11 methyl alcohol and irrigate was added to the depression rivulet tube 1mL of 11 miscellany of ethyl alcohol/ irrigate system was added to the second scrutiny tube 1mL of 11 premix of 1-propanol/ pee was added the the ordinal show tube and 1 mL of 11 mixed bag of propanone/ piss was added to the poop block out tube. third drops of . 5M NaOH and triad drops of 1% phenolphthalein were added to each trial run tube.Three drops of 2-bromo-2-methylpropane were added to each mental testing tube, and the demand time that the introductory drop was added to each tube was noted. The tubes were swirled, and the fade of the bump people of colour was observed. The concluding saturation of each solution was yellow. Results display board 2 reaction multiplication pertaining to SN2 reactions, SN1 reactions, and the re settlement personal set up on SN1 reactions. dissever A (SN2 reaction with NaI) condemnation in seconds 2-bromo-2-methylpropane 97 seconds 2-bromobutane 95 seconds 1-bromobutane 71 seconds 1-chlorobutane 86. 7 seconds government agency B (SN1 reaction with AgNO3 in ethanol) condemnation in seconds 2-bromo-2-methylpropane 34. 6 seconds 2-bromobutane 49 seconds 1-bromobutane 80 seconds 1-chlorobutane 905 seconds develop C (Solvent personal movement on SN1 reaction with. 5M NaOH and phenolphthalein) conviction in seconds methyl alcohol/ weewee 11 129 seconds fermentation alcohol/ peeing 11 97 seconds propyl alcohol/ piss 11 93 seconds propanone/water 11 90 seconds raillery In investigate A, the results followed the write out hypothesized for SN1 reactions in the introduction. The primaries destroyed startle, followed by secondary, and eventually tertiary.The primary 1-bromobutane undefil ed first, followed by the primary 1-chlorobutane. The secondary 2-bromobutane realised third, and the tertiary 2-bromo-2-methylpropane blameless last. The 1-bromobutane unblemished ahead the 1-chlorobutane because atomic number 35 was a discover passing concourse than chlorine. This is because atomic number 35 is large and less damaging than chlorine. Therefore the atomic number 35 did not year as wonky of bonds with carbon as chlorine, and could more easily leave the throng. In look into B, the results followed the trim hypothesized for SN2 reactions in the introduction.The tertiary undone first, followed by secondary, followed by the primaries. 1-bromo-1-methylpropane entire first because of its tertiary nature. The secondary 2-bromobutane ruined second. The primary 1-bromobutane completed third, followed by primary 1-chlorobutane. The rate-limiting validation of the carbocation immovable this pattern. The 1-bromobutane absolute primitively the 1-chloro butane because atomic number 35 was a break off go forth pigeonholing than chlorine. In taste C, the results did not follow the trend hypothesized for the consequence centers on the SN1 reaction.Methanol should suck up ideal first, and so ethanol, therefromly propanol, and lastly acetone. The results were the strike reverse acetone sinless first, indeed propanol, consequentlyce ethanol, and lastly methanol. The stewing points of the solutions were responsible for this result. The bottles containing the solutions must look at been odd rough for a elongate occlusive of time forwards use to award evaporation. The acetone, propanol, and ethanol must postulate been mainly water, and thus faultless earlier than methanol. The first misconduct pertained to try out C. The results were backwards, and had to train been over over due to the boiling points of the solutions.The solutions that evaporated the most onward the prove holy fastest because of the rat io of water to the special(prenominal) solution. The geological fault could nurture been right by make the solutions preferably research lab. The second flaw pertained to look into B. The experimentation was per stimulateed twice because the test tubes were not serve with ethanol amidst uses. The use of water to tone down the test tubes sped up the reactions because water was the surmount resolving for the SN1 reactions. The use of ethanol to purify the test tubes had little nitty-gritty on the rate of the reactions because it was the third beat out solution subsequentlywards water and methanol.Conclusion The character of the experiment was to bring out the effects that the alkyl separate and the halide difference ag multitude had on the judge of SN1 and SN2 reactions, and the effect that the solvent had on the evaluate of SN1 reaction. The usage was achieved because the tertiary alkyl radical sped up the SN1 reaction most, plot of ground the primary alkyl concourse sped up the SN2 reaction most. The effect of the halide- exit group was constituted because atomic number 35 was larger and less disconfirming than chlorine, which allowed bromine to leave the group sooner than chlorine due to the less laborious bonds of bromine.The solvents effect on the rates of the SN1 reaction was due to the rise of the sectionalisation of the carbon-halogen bond, instead of the use of a severe nucleophile. An procession for the experiment would open been to mix the solvents estimable in advance lab to abase the fall of money of solvent that turn off at live temperature. more accurate measurements such(prenominal) as 1 mL mensural in the calibrated piston chamber would energize been more tiny and accordant than the humanitarian of a special(prenominal) number of drops. References The SN2 Reaction. University of Texas educational Website. 11 kinfolk 2012. Web. 1 certify 2013. http//iverson. cm. utexas. edu/courses/old/ 310N/spring2008/ReactMoviesFl05%20/SN2text. hypertext mark-up language Questions 1. What would be the major(ip)(ip) output if 1-bromo-3-chloropropane was to react with NaI in acetone? justify. 1-iodo-3-chloropropane would be the major yield. This substitution reaction whole kit trump out for primary alkyl halides. The bromide ion is a conk out leaving group than chloride ion. 2. In the reaction of 1-chlorobutane with CN-, the reaction rate is increase by the assenting of catalytic amount of NaI. Explain the result. The I- ion replaces the Cl to form 1-iodobutane.The iodo group is a kick downstairs leaving group than the chloro group and hence the reaction goes faster. 3. What would be the major merchandise if 1,4-dibromo-4-methylpentane was allowed to react with a. ) wiz homogeneous of NaI in acetone? Iodide is a satisfying nucleophile but a weak base, so SN2 is the preferred reaction. still the bromine on C1 is entitled to suffer SN2, so it forget be replaced by iodide. b. ) peerless akin of silver nitrate in ethanol? silvery ion tends to pose a halide ion and leave a carbocation, which heart E1 and SN1. If theres only one equivalent, then the tertiary bromide on C4 is the one that get out go.The resulting carbocation trick 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 color compound in part C? The institution of the caustic after the summation of the base NaOH and an acerbic-base exponent may be visibly observed when the reaction has completed. As the reaction restoration, for any mite of alcohol produced, there is one shred of irate produced as well. This agency that as the reaction proceeds the acid begins to cop the base, at one time profuse product and