Physical Data Ta$le! %ompond
&olar 'ei(ht
mmol
'ei(ht
+olme
*"1**
Densit y ()m* *")2
Boilin ( Point % +1"1
azards
2**
'rritant
*".ml
&eltin ( Point % 2122* 14+14) -.)
Tetraphenylcyclopentadienone
3)4"4)
nthranilic acid
13"14
*"2+** ) *"32)2
*"*4.
*"1
$
1,2-dimetho$yethane (!/0
*"12
4")1
*"434
*")+)3
'soamyl nitrite
11"2
*"44)
*"*.2.
*").
*"*+
-
-
/ethanol
32"*4
4"3
1".)2
*"1
2m
-"+
+4"
1,2,3,4tetraphenylnaphthalene
432".
"1)2
*"*g
4)+"1
$
12*1
4)+"1
$
).
'rritant
armful if inhaled, irritant, flammabl e To$ic if contact sin, flammabl e 'rritant 'rritant
Procedre!
Reaction Mixture bout *"1213g of Tetraphenylcyclopentadienone, *"*4)g of nthranilic cid, and *1"2m of 1,2-dimetho$yethane (!/0 5ere added to a .m conical &ia" magnetic spin &ane 5as also included" cleaned and dried 5ater-6aceted condenser 5as then attached to the top of the conical &ial" bout *"*+m of 'soamyl nitrite 5as transferred to a 3m conical &ial" The &ial 5as capped to pre&ent e&aporation 5hile in route bet5een fume hoods" This 'soamyl nitrite 5as dissol&ed 5ith about *".*ml of 1,2-dimetho$yethane" Running the Mixture The .m conical &ial mi$ture 5as heated on an aluminum bloc set to around 14* degrees 7elsius" 8hen the solution began to boil, the 3m conical &ial solution 5as added from the top of 5ater the condenser 5ith the use of a clean 9asteur pipette, reaching as close to the boiling solution as possible" The 3m conical &ial 5as then rinsed 5ith a fe5 drops (about 1* 1,2-dimetho$yethane and added to the reaction mi$ture being heated" The mi$ture 5as left to boil until color changed from deep purple(tetra to a yello5 orange solution" The color had not changed after 1. minutes of heating, so 1 drop of 'soamyl nitrite 5as added to the heating mi$ture" The color changed to an off peach- being color" solation o! "rude #etraphenylcyclopentadienone fter the color change, the mi$ture 5as remo&ed from heat, separated from the app aratus, and allo5ed to cool in the conical &ial" :nce cooled, a clean 9asteur pipette 5as used to transfer this solution to a clean beaer containing a mi$ture of about .ml of 5ater and 2ml of methanol"
This ne5 mi$ture 5as then s5irled and stirred 5ith a glass rod to brea do5n any solid formed" The solid 5as of a light beige color s5imming in yello5 tinted solution" This solid 5as then collected o&er irsch funnel" 'ce-cooled methanol(1*m 5as used to rinse the beaer and poured o&er the solid in the funnel" :nce filtering and drying 5as concluded, this crude product 5as 5eighed (*"+.+3 g" "rystallization o! #etraphenylcyclopentadienone The crude product 5as then purified by crystallization from hot 2-propanol in order to remo&e any impurities" The crude material 5as placed in a 2.m flas and placed on a hot plate alongside a flas containing about 12ml of 2-propanol as 5ell" s the 2-propanol became 5arm, a 9asteur pipette 5as used to transfer it into the flas containing the crude material until it dissol&ed" !ue to time constraints, the lab 5as continued on day t5o at this step of the procedure (dissol&ing the crude material 5ith hot sol&ent" spatula 5as used 5hilst heating to brea do5n any thic solid pieces and to #uicen the dissol&ing process" :nce the crude product had been dissol&ed, the flas 5as remo&ed from heat and allo5ed to cool to room temp" fter about 3 minutes of cooling to room temperature, the flas 5as placed in an ice bath for about 2* minutes 5ith the sides of the flas being scratched 5ith a glass rod to induce crystallization" fter the cooling process, crystallization could be seen inside the flas and this flas contents 5ere run through a irsch funnel under &acuum suction" The flas 5as rinsed 5ith ice-cold 2-propanol" The cold sol&ent 5as also used to 5ash the pure product in the funnel" The solid product 5as allo5ed to dry completely, 5eighed (*"*g" Melting $oint Determination :nce the solid 5as completely dry, the melting point 5as determined" The melting point 5as taen t5ice as the pure form of 1,2,3,4-tetraphenylnaphthalene e$ists in t5o forms, each 5ith t5o different melting points (1-2** and 2*4-2*." Spectroscopy n ' spectrum 5as obtained of the pure sample" The solid 5as dissol&ed in a test tube 5ith about *"*.g of solid and about . drops of dichloromethane" This solution 5as placed on clean salt plates 5hich 5ere used to get a reading on the ' spectrum" Reslts and .$ser/ations! .$ser/ation! The mi$ture of isoamyl nitrite and anthranilic acid in the 3m conical &ial resulted in a bright blood-red colored solution" 8hile being transferred don into the 5ater condenser, some drops 5ere left trailing the inside of the condenser of maing it into the solution" :nce added to the heating solution, the mi$ture faded orange and finally ended up 5ith pale yello5 and peach tints" The entire color changing process too appro$imately 2* minutes 5ith the need of an additional isoamyl nitrite drop to help change the color and mo&e the reaction for5ards" The the suctioning created by pressing do5n 5ith the palm of the hand 5ored far better than lea&ing it to gra&ity alone, ho5e&er, the glo&ed palm 5ould be co&ered in the solution trying to be filtered, hence, much product 5as lost in this process" The crude product 5as of a peach beige color and &ery dull" fter adding 2-proponal and heating mildly for 2 minutes and 5ith the aid of scratching flas 5all and placing into ice-5ater bath, the crystallization 5as pretty efficient and small 5hite shiny crystals 5ere obtained &ia &acuum filtration"
Data!
Theoretical ;ield 0112(
ctual ;ield 00(
< ;ield 05
/elting 9oint ange 1-200% 6 204 -20%
ppearance 'hite, shiny crystals 7ithot apparent odor
%alclations!
%imiting Reagent 1" Since there 5ere more mmoles of isoamyl nitrite (*"2+*) than those of anthranilic acid(*"44)g, anthranilic acid 5as the limiting reagent during benzyne formation" 2" =or more mmoles of benzyne 5as obtained, Tetraphenylcyclopentadienone 5as the limiting reagent for !iels-lder reaction" For the !ormation o! &enzyne: nthranilic acid > (*"*4.g?13"14g@mol A 1*B3 > 03282mmoles 'soamyl nitrite > ((*"*+mC*").g@m ?11"14g@mol A1*B3>*"44)mmoles Therefore, anthranilic acid 5as the limiting reagent" For the Diels-Alder reaction !orming 1'2'(')-tetraphenylnaphthalene Tetraphenylcyclopentadienone > (*"1**g?3)4"4)g@mol A1*B3>02901mmoles 03282mmoles of Anthranilic acid Tetraphenylcyclopentadienone mmole amount 5as less than that of Denzyne" Thus, the limiting reagent 5as Tetraphenylcyclopentadienone Theoretical /ass ;ield% *"***2+**)molC432"..g@mol>0112( 1,2,3,4-Tetraphenylnaphthalene ctual ;ield% *"*g < ;ield% (*"*g @ *"112g $ 1**< > 05 ' Spectrum% The only real peas on the spectrum 5as that of sp3-7(3*.4 cm-1 bonds and sp2-7(2)+ cm-1 bonds" There 5as another pea in the double bond zone at 23*. cm-1 indicati&e of a 7>7" ll other peas 5ere to 5ea and randomized to be indicati&e of anything substanti&e" Data Analysis! The purpose of this lab 5as to produce the product 1,2,3,4-tetraphenylnaphthalene and then be able to pro&e that our product is in fact this" =irst, the melting point tells the purity of the pure sample obtained" The results from this e$periment 5ere 1-2** and 2*4-2*. in degrees of 7elsius" The literature &alue is 1+-1 and 2*3-2*. degrees of 7elsius" T5o melting point ranges presented because 1,2,3,4-tetraphenylnaphthalene crystals had t5o forms of different crystalline (allotropes 5ith t5o melting point ranges" The higher melting point range 5as
obtained after solidification" 8ell, the fact that my data 5as not too mange digits and &alues a5ay from the literature &alue speas to the high purity le&el of the product that 5as obtained" o5e&er, the shift in the first melting point indicates the presence if impurities" This can be due to the unfortunate malfunctioning of the fume h ood &acuum system in aiding the filtration process" s stated before, 5hen ' used the palm suction method to help &acuum the solution, much of the solution 5ould suc up5ards as 5ell, and spill out of the funnel" Eot only 5as there a significate amount of product lost right there, but it speas to the inade#uate filtering step, allo5ing for impurities to pass through" =urther, the percent yield 5as calculated as *".<" That is a fair assessment to the performance of these lab procedures and general laboratory error" 'n general, most of this percent error loss is due to loss of material &ia transfer bet5een &essels and purification apparatuses" This could also be due to incomplete reaction and reagents that did not complete into products, leading to unreacti&e impurities in the final product" =urther, the ' spectra that 5as obtained for this sample does not offer much assistance in determining the purity of the product" /any people had been dropping the salt plates on the ground and or lea&ing the sol&ent bottles open, 5hich could ha&e led to inaccurate ' spectra readings" /oreo&er, for better data results ne$t time, a &acuum system is a must as 5ell as ha&ing careful mi$ture and transfer techni#ues" This 5ill result in less loss of product could contribute to a more p urified product" :&erall, this 5as a successful e$periment 5as in 5hich Tetraphenylcyclopentadienone reacted 5ith benzyne intermediate formed, gi&ing a fairly pure 1,2,3,4-tetraphenylnaphthalene product and reasonable yield" 7areful analysis using the melting point determination confirmed the purity and identity of desired naphthalene, 1,2,3,4tetraphenylnaphthalene" %onclsion! The purified product of 1,2,3,4-Tetraphenylnaphthalene 5as identified 5ith a melting point range of 1-2** and 2*4-2*. in degrees 7elsius and a percent yield of *".<"
Post *a$ :estions
1- Denzyne is not a stable intermediate, 5hat is the dri&ing force for the formation of that unstable intermediateF a" The formation of benzyne intermediate 5as a e 7hatelier e#uilibrium reaction" Dased on e 7hatelierGs principle, e#uilibrium 5ould be dri&en to product side if the reagent 5as added or the product 5as remo&ed" 'n this e#uilibrium, the products, carbon dio$ide and nitrogen gas, 5ere both gases" s soon as they 5ere generated, they directly escaped from the solution" Thus, this 5as a natural Hproduct remo&ingI process and the e#uilibrium 5as constantly dri&en to the benzyne formation direction" 2- 8hat is the dri&ing force for the !iels-lder reactionF a" =or the same reason, during the !iels-lder reaction bet5een benzyne and Tetraphenylcyclopentadienone, the generation and escaping of carbon mono$ide during aromatization contributed to dri&ing force of 1,2,3,4-tetraphenylnaphthalene formation" b" 'n general, the electron deficient nature of the dienophile and the relati&e electron‐ rich nature of the diene are the cause of action for the progress of the reaction" 'f you mae one electron‐deficient and one electron‐rich, there becomes more of a dri&ing force for the reaction" 3- 8hat is the dri&ing force for loss of carbon mono$ideF a" Denzyne 5as immediately trapped by Tetraphenylcyclopentadienone in !iels- lder reaction path5ay, forming an acti&e intermediate" earrangement and aromatization of the ring for intermediate 5as accomplished 5hen carbon mono$ide 5as lost" The desired naphthalene product 5as finally gi&en" This reaction 5as performed in situ because benzyne 5as &ery unstable intermediate b" !uring the !iels-lder reaction, 5hen the diene and the dienophile react and a ne5 bond are being created, the bridge pushed up5ards containing the 7>: bonds actually lea&es as J7: due to arro5 pushing and to mae bonds bet5een diene and dienophile" ence, the ne5 c-c bond causes the 7>: to be pushed out of the structure and form the loss of carbon mono$ide" 4- 7alculate the percent yield using your crude product" a" (*"*).+3 g 7rude @ *"112g Theo $ 1** > +".< .- 7alculate the percent yield using your purified product" a" (*"*g 9ure @ *"122g Theo $ 1** > *".< +- o5 is the ' of the product different from anthranilic acid the starting materialF a" The most ob&ious difference seen bet5een the t5o spectrums is the 7:: pea" The anthranilic acid structure contains this functional group so 5e see a 5ide dipped pea at around 3.**-2.** cm-1" The final product of 1,2,3,4-Tetraphenylnaphthalene does
not contain such a functional group so there is an apparent absence of it on its ' spectra" 'nstead, 5e see sp3-7 and sp2-7 bo nds, 7>7 bonds"
