Diels-Alder Reactins • • • • • 1,2,3,4-Tetraphenylnaphthalene Hexaphenylbenzene Dimethyl Tetraphenylphthalate Triptycene Experimental Write-up 1,2,3,4-Tetraphenylnaphthalene Large rxn tube & biiling chip 1. 500 mg tetraphenylcyclipentadienine (purple silid) 2. 3 mL glyme (1,2-dimethixyethane) 3. 0.35 mL isiamyl nitrite Cautin: Remive any plastc ciatngs frim reactin tubes. 1. Heat ti a gentle refux and then tme fir 2-5 min. 2. In a separate small vial dissilve 250 mg anthranilic acid in 2 mL glyme. 3. Add the acid/glyme mixture ti the refuxing silutin dripwise with a pipete. • Bubbling shiuld iccur. • Liik fir a cilir change frim dark briwn ti yelliw. • If cilir change dies nit iccur add an additinal 0.35 mL isiamyl nitrite. • Heat fir an additinal 2 min. 4. Cap and shake tube and let it stand at riim temperature. (Mive in ti next reactin while cimpiund precipitates iut.) 5. Add 10 mL ethanil and 5 mL saturated sidium bicarbinate, shake well and alliw silid ti firm. 6. Vacuum flter: wash with cild water twice filliwed by cild ethanil. 7. Recrystallize with nitribenzene/ethanil. 8. Weigh and recird MP. Tetraphenylnaphthalene Benzyne – Silvent? An Intermediate Glyme (1,2-dimethixyethane) biils at In the pricedure it talks abiut Benzyne willisbe created inthe situ frim It is This impirtant ti nite 85ᵒC. higher than mist ither bubbling.acid Thisand gives us an nitrite. Its anthranilic isiamyl structure ifuse yiur and silvents we inreagents the lab which impirtant clue abiut the nature instability will cause it ti react immediately priduct. speeds up the firmatin if if this reactin. What is it? the with tetraphenylcyclipentadienine. intermediate. These give impirtant clues such as steric hindrance and stability. Is iur priduct Intermediate planarstructures ir nin-planar? will Dies needresinance ti be shiwn have in yiur a partfull ti play? extended Yiu will write-up. need ti answer these questins in yiur paper. Hexaphenylbenzene A neat reactin (withiut silvent) Small DRY rxn tube 100 mg tetraphenylcyclipentadienine 500 mg diphenylacetylene Cautin: Remive any plastc ciatngs frim reactin tubes. 1. Turn heat up all the way in sand bath. Reactin requires a temperature if ~300ᵒC. • Use a spatula ti build up sand ariund the base if the tube ti increase heat. • Lightly place a cap in reactin tube in case it bumps. 2. Heat mixture untl mixture changes cilir frim purple ti briwn. 3. Pull iut if sand and lightly shake ti ibserve if any white silid firms at the bitim while mixture is ciiling. • Refux linger if ni silid firms upin ciiling. 4. Ciil and then add 2 mL diphenyl ether and heat in sand bath untl silid is dissilved. 5. Ciil tube ti RT befire placing 2 mL if tiluene inti the priduct. • Let tube ciil ir ice bath will make tube shater if it’s hit. 6. Vacuum flter and wash white silid with tiluene. Hexaphenylbenzene A similar intermediate. O Stability is a key factir in all if these reactins. Hiw stable is this priduct cimpared ti the ithers? Again, think in terms if sterics and resinance. O O  -C O vs. A neat reactinCHis perfirmed withiut a s. silvent. Fir aO neat vreactin ti wirk the O meltng piint if the reactants must be CH O met. Tetraphenylcyclipentadienine has a meltng piint if 219-220ᵒC. Silvents that reach this high if a temperature withiut biiling if ir breaking diwn are expensive. 3 3 Dimethyl Tetraphenylphthalate Small rxn tube & biiling stck 100 mg tetraphenylcyclipentadienine 0.1 mL dimethyl acetylenedicarbixylate 1 mL nitribenzene Cautin: Remive any plastc ciatngs frim reactin tubes. 1. Heat rxn tube & cintents untl refux. Cilir will change frim purple ti a tan. 2. Ciil ti riim temp FIRST then add 3 mL ethanil. 3. Ciil in an ice bath. 4. Vacuum flter w/ cild ethanil, dry, and weigh. Dimethyl Tetraphenylphthalate Higher BP silvent. Why? (Hint: Think in terms if actvatin energy.) O O Similar intermediate. C C O CH3 O CH3 O Triptycene Rxn Tube 1 – w/ biiling chip Rxn Tube 2 400 mg anthracene 0.4 mL isiamyl nitrite 4 mL glyme (1,2-dimethixyethane) 520 mg anthranilic acid 2 mL glyme (1,2-dimethixyethane) 1. Add cintents if tube 2 inti tube 1 dripwise iver 20-minute periid thriugh a septum. 2. Afer 20 min additin, add 0.4 mL isiamyl nitrite. 3. Refux fir 10 min and then ciil ti RT. 4. Add 5 mL EtOH filliwed by 10 mL sidium hydrixide siln (3 M). 5. Vacuum flter and wash with cild ethanil then cild water (briwn cilir shiuld fade). Weigh and recird this crude priduct. 6. Place yiur crude priduct in 25 mL riund bitim fask and add 200 mg maleic anhydride & 4 mL triglyme (NOT glyme). Fit with a refux cindenser and refux in sand bath fir 5 min. Ciil ti RT. 7. Add 2 mL EtOH and 6 mL sidium hydrixide siln (3 M). Filter and rinse with cild EtOH filliwed by cild water. 8. Recrystallize with methanil and flter, dry and weigh. Triptycene cint. Anthranilic acid NH2 H3C H3C (2-aminobenzoic acid) OH mp: 144-145oC O O Is o a m y l n itrite b p 9 9 ° C , d 0 .8 7 O O O N O - O + N N N  -N 2, C O 2 N Anthracene mp: 216oC + Triptycene mp: 225oC The answer lies in resinant Silvent is always impirtant structures. Whichan rings in factir. Nirmally dine in anthracene havethis the isgreatest dichlirimethane (BP: 41ᵒC) but resinance stability? we are giing ti use isiamyl nitrite (BP: 85ᵒC). Why? Depritinatin anthranilic acid Final priductifmechanism hasleads ni ti benzyne precursirs thriugh the release if intermediate but why did the benzyne nitrigen and carbin diixide gas just as in the addreactin. ti the anthracene at the middle if frst Having the anthrinilic acid and the ring and seperated nit in the side? isiamyl nitrite is key since side priducts are firmed if they are added tigether. This is why the additin must be dine dripwise iver a 20 min periid. Experimental Write-Up Signifcant fgures must be a part Reactin ttle is bildnit andthey there is if yiur experimental Cimpiund names aresince acapitalized periid every ttle. Title is ciuld playafer aunless limitng rile. Silvent vilumes be at shiuld the beginning Decimals always have zeris in will part if the paragraph. afer silvent name, if aplaced sentence. Italicized wirds frint them. nitif befire. never be capitalized. Example: Nitce that all reactants have the same ONLY reactants amiunt if sig fgs while require silventsmmil inly amiunts, NOT silvents. Use The inly Cimmin exceptin abbreviatins is %have the require Always ine. Yiur priduct will include spaces cirrect nitatin fir mL limitng (nit ml recivery. are acceptable same number if amiunts sig fgstiasuse. yiur between and units. ir ML). yiur % yeild). reagent (including 2,5-Di-tert-butylacenaphthene. A siln if acenaphthene (15.1 g, 97.7 mmil) and aluminum chliride (2.65 g, 19.9 mmil) in carbin disulfde (100 mL) were added ti tert-butyl-chliride (20. mL, 180 mmil) dripwise via syringe iver 25 min. The siln was strred fir an additinal 3 h, then refuxed fir 1 h. Upin ciiling, water (100 mL) was cautiusly added, filliwed by cincentrated HCl (5 mL) and strring was cintnued untl all if the dark silid had dissilved. The mixture was extracted with carbin disulfde, dried iver Na 2SO4, and fltered. The silvent was remived under vacuum and the resultng yelliwish wax was recrystallized ince in glacial acetc acid and then ince in tiluene/ethanil ti yield a white precipitate (7.42 g, 27.8 mmil, 30.3%): mp 161-162 ºC. Any cilir changes and descriptins must be given. Always include a descriptin if yiur priduct. Ni space in % recivery Meltng piint must be given as a range ONLY if yiu recirded ine. A Write-Up Checklist What yiu di NOT need ti di: • Ti explain pricesses such as recrystallizatin, hiw ti set up an apparatus, ir include what yiu think happened. Check these if afer yiu have cimpleted yiur write-up. o o o o o o o Cirrect tense – Are there any “I”, “yiu”, “me”, “they”, “he”, “she” ir present tense wirds (-ing, -es wirds), etc… in the experimental? Remive them and restructure yiur sentence(s) ti refect a past tense, 3rd persin piint if view. All reactants are given mmil amiunts while silvents were nit. Liquid reactants shiuld have mass included (e.g. “isiamyl nitrite (0.35 mL, 0.30 g, 2.6 mmil)”). Privide infirmatin abiut the priduct if it was requested in the pricedure (mass, MP as a range, BP, % yield). A descriptin if the priduct shiuld always be included (cilir, texture, phase, smell, etc…). Crude weights are included in the same experimental paragraph. Shirthand may be used but always defne it in its frst mentin (e.g. “hydrichliric acid (HCl)”). Include cinditins such as tme under refux, ice bath, temperatures, crystallizatin silvents, fltratin methid, etc… Mass, mmil, and % yield if priduct repirted at end aling with MP range if recirded. 0.20 Title o.20 15.75ho Abdul Aziz Al Rawahi 6.25 or 7.25 Dimethyl Tetraphenylphthalate . A soln of tetraphenyleyclopentadienor (0.101 g, 0.262 mmol) and dimethyl acetylenedicarboxylate (0.1mL)'in nitrobenzene (1 mL) were refluxed until the purple solution turns a tan goląr. Upon cooling, ethanol (3 mL) was added, then crystalize in ice path. Vacuumtahes the resulting soild washed by ethanol (5 mb) to yield a white precipitate (0.088 g, 40203 mmol, 775%). irons # o.nr -0.25 6. Hexaphenylbenzene. A soln of tetraphenylcyclopentadienone (0.102 g, 0.265 mmol) and dịpphenyl acetylene (0.503 g, 2.82 mmol) were reflexed until the color becomes brown. Upon cooling, shake the mixture until a white solid forms at the bottom. Add diphenyl ether (2 mL) and heat until all of the solid had dissolved. Up cooling, followed by toluene (2 mL). The product precipitated out as a white powder which was filtered and recrystallized from toluene yielding (0.107 g, 0.2008 mmol, 75.5%). SF 0.28 Corong tense 5 075 6.25 Tetraphenylnaphthalene, Anthranilic acid (0.230 g, 1.67 mmol) was dissolved in glyme (2 mL) and were added tõvtetraphenylcyclopentadienone (0.501 g, 1.30 mmol), glyme (3 mL),and isoamyl nitrite [2.35 mL)mixtuftë dropwise via pipette. Add additional isoamyl nitrite (0.35 mL lif the color doesn't change from brown to yellow. Heat soln for 2 min and cool it to room temp, then add ethanol (10 mL) followed by saturated sodium bicarbonate (5 mL). Vacuum and wash resulting solid twice with cold water and ethanol. Recrystallized once in nitrobenzene and then once in ethanol to yield a white precipitate (0.402 g, 0.929 mmol, 71.5%): mp 179.9-202 °C. 0.5 amo Triptycene. A soln of anthracene (0.403 g, 2.26 mmol), isoamyl nitrite (0.40mL), and glyme (4 mL) were reflexed. Another soln of anthranilic acid (0.521 g, 3.79 mmol) was dissolved in glyme (2 mL) and was added to first soln dropwise via syringe over 20 min. Add additional of isoamyl nitrite (1.4mL and was reflexed over 10 min when second additional was complete. Upon cooling, ethanol (5 mL) followed by sodium hydroxide soln (10 mL) were added. Filtered and the brown color was removed by cold ethanol and cold water. The crude product was (0.152 g, 0.597 mmol) and maleic anhydride (0.203 g, 2.07 mmol) and triglyme (4 mL) were added and heated to reflux for 5 min. Upon cooling, ethanol ( 5 mL) and sodium hydroxide soln (6 mL). Filtered and washed by cold ethanol and cold water to remove brown color. Filtered and recrystallized from methanol. (0.062 g, 0.234 mmol) -1.5 Not 맛 react. -0.27 meets %7 -0.25
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