Organic Chemistry 4 Lab Questions And Reports paper

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please answer each chapter question with lab report for 4 chapters:

1/ Nitration of methyl benzene

2/ Grignard synthesis of triphenylmethanol and benzoic acid

3/ Nitric acid oxidation of benzoin

4/ Borohydride reduction of a ketone

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Hydrocarbons Do Not Dissolve In Concentrated Sulfuric Acid, But Methyl Benzoate Does. Explain this differences and write an equation showing the ions that are produced.

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Chapter 28 Nitration of Methyl Benzoate 405 Cleaning Up. Dilute the filtrate from the reaction with water, neutralize with sodium carbonate, and flush down the drain. The methanol from the crystalliza- tion should be placed in the organic solvents waste container. QUESTIONS 1. Hydrocarbons do not dissolve in concentrated sulfuric acid, but methyl ben- zoate does. Explain this difference and write an equation showing the ions that are produced. 2. What would you expect the structure of the dinitro ester to be? Consider the directing effects of the ester and the first nitro group upon the addition of the second nitro group. 3. Draw resonance structures to show in which position nitrobenzene will nitrate to form dinitrobenzene. 4. Assign the peaks at 3101 cm-?, 1709 cm!, and 1390 cm-1 in the IR spectrum of methyl 3-nitrobenzoate (Fig. 28.3). Microns (um) FIG. 28.3 3.0 4.0 2.5 3,0 3,5 5,0 6.0 The IR spectrum of methyl 3-nitrobenzoate. The broad peak at 3400 cm-1 comes from water in the KBr disk. i 10 15 20 MN (%) อวบ 1599 cm-1 Chapter 38 - Grignard Synthesis of Triphenylmethanol and Benzoic Acid 505 8. BENZOIC ACID Video: Macroscale Crystallization Wipe the frost from a piece of dry ice, transfer the ice to a cloth towel, and crush it with a hammer. Without delay (so moisture will not condense on the cold solid), trans- fer about 10 g of dry ice to a 250-ml beaker. Cautiously pour one-half of the solution of phenylmagnesium bromide prepared in Experiment 1 onto the dry ice. A vigorous reaction will ensue. Allow the mixture to warm up, and stir it until the dry ice has evaporated. To the beaker, add 20 mL of 3 M hydrochloric acid; then heat the mixture over a steam bath in the hood to boil off the ether. Cool the beaker thoroughly in an ice bath, and collect the solid product by vacuum filtration on a Büchner funnel. Transfer the solid back to the beaker and dissolve it in a minimum quantity of saturated sodium bicarbonate solution (2.8 M). Note that a small quantity of a byproduct remains suspended and floating on the surface of the solution. Note the odor of the mixture. Transfer it to a separatory funnel and shake it briefly with about 15 mL of ether. Discard the ether layer, place the clear aqueous layer in the beaker, and heat it briefly to drive off dissolved ether. Carefully add 3 M hydrochlo- ric acid to the mixture until the solution tests acidic to pH paper. Cool the mixture in ice and collect the product on a Büchner funnel. Recrystallize it from a minimum quantity of hot water and isolate it in the usual manner. Determine the melting point and the weight of the benzoic acid; calculate its yield based on the weight of magnesium used to prepare the Grignard reagent. Cleaning Up. Combine all aqueous layers, dilute with a large quantity of water, and flush the slightly acidic solution down the drain. The ether-hexanes mother liquor from the recrystallization goes in the organic solvents waste container. The TLC developer, which contains dichloromethane, is placed in the halogenated organic waste container. Calcium chloride from the drying tube should be dis- solved in water and flushed down the drain. QUESTIONS 1. Triphenylmethanol can also be prepared by reacting ethyl benzoate with phenylmagnesium bromide, and by reacting diethylcarbonate with phenylmag- nesium bromide. Write stepwise reaction mechanisms for these two reactions. O C,H,OCOC2H5 2. If the ethyl benzoate used to prepare triphenylmethanol is wet, what byprod- uct is formed? 3. Exactly what weight of dry ice is needed to react with 2 mmol of phenylmag- nesium bromide? Would an excess of dry ice be harmful? 4. In the synthesis of benzoic acid, benzene is often detected as an impurity. How does this come about? 5. In Experiment 3, the benzoic acid could have been extracted from the ether layer using sodium bicarbonate solution. Write equations showing how this might be done and how the benzoic acid would be regenerated. What practical reason makes this extraction method less desirable than sodium hydroxide extraction? Chapter 54 - Nitric Acid Oxidation; Preparation of Benzil from Benzoin 667 FIG. 54.6 יחי The 'H NMR spectrum of benzil (250 MHz). יזיז wheth 8.0 7.6 7.4 7.8 PPM (8) ОО C-C 7.0 3.0 6.0 2.0 9.0 1.0 8.0 0 5.0 4.0 PPM (8) quiz QUESTIONS 1. Assign the peak at 1646 cm- in the IR spectrum of benzil (Fig. 54.5). 2. Assign the peaks at 3410 cm-1 and 1664 cm-l in the IR spectrum of benzoin (Fig. 54.2). WAS UP, sodium borohydride (large excess). C00 and the yellow color disappears in 2-3 minutes. After a total of 10 minutes add 5 mL of water, heat to the boiling point, filter in case the solution is not clear dilute to the point of saturation with more water (10 mL), and set the solution aside to sodium chloride to the filtrate until no more of the salt will dissolve. Collect the the yield is about 0.35 g. A second crop of material can be obtained by adding solid crop of crystals via filtration and wash the crystals with water. second Cleaning Up. Dilute the aqueous filtrate with water, neutralize it with acetic acid (to destroy the borohydride), and flush the mixture down the drain. NS 1. Using the R,S system of nomenclature, draw and name all of the isomers of hydrobenzoin. 2. Calculate the theoretical weight of sodium borohydride needed to reduce 50 mg of benzil. _rning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part
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Explanation & Answer


Nitric Acid Oxidation of Benzoin to Benzil
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Purpose: The purpose of this experiment is to oxidize benzoin into benzil in an acidic
A compound which has two ketone bunches quickly adjoining each other is alluded to a diketone. In this investigation we will incorporate the -diketone benzil by oxidizing benzoin.
Since this is an oxidation, a liquor aggregate is being changed over to a ketone bunch in the
response. By and large, optional alcohols are oxidized with sodium dichromate in a corrosive
arrangement. For benzoin, be that as it may, the yield is lower utilizing dichromate since a great
part of the material is changed over into benzaldehyde by cleavage of the security between two
oxidized carbon particles, and actuated by both phenyl gatherings. Having a carbonyl in a
position vicinal to the liquor, with two phenyl bunches accessible to settle moderate
carbocations, makes the carbon-carbon security powerless to cleavage. Utilizing chromic
corrosive likewise creates a generous measure of lethal and destructive waste, and is unsafe to
manage in substantial amounts. So also, hydrobenzoin, on oxidation with dichromate or
permanganate, yields predominantly benzaldehyde and just a hint of benzil. Benzoin can be
oxidized to the -diketone, benzil, in all respects proficiently by nitric corrosive or by copper
(II) sulfate in pyridine. To keep away from cleavage of the atom, the milder oxidizing operator
nitric corrosive functions admirably. The change from the second middle of the road to the third
is an interior corrosive/base response, where a proton exchanges starting with one oxygen then
onto the next.
Chemical Equations:
Table of Physical Constants:

Mol Formula








Nitric Acid



























1. Place 0.500 g of benzoin and 1.75 mL of HNO3 in a small Erlenmeyer flask.
2. Heat the mixture in a boiling water bath for 11 min. (Caution: produces nitrogen oxides.).
(Be sure all of the benzoin is washed down inside the flask and is oxidized).
3. Add 10 mL of water to the mixture, cool to room temperature, and stir the mixture for 1-2
min to coagulate the precipitated product.
4. Cool the flask in an ice-bath and collect the product by vacuum filtration.
5. Scrape the benzil onto a piece of filter paper, squeeze out excess solvent, and allow the
solid to dry.
6. Weigh the product and calculate the percent yield.

Observations: When adding HNO3 to the flask that contains 0.500 g of benzoin, the response
turned a splendid yellow shading. At the point when the blend was set in the hot shower, it
initially turned an orange shading then inside a moment turned a darker orange shading and
started to deliver dark colored vapor. At the point when the blend was removed from the
warming shower and left to cool it by and by turned a splendid yellow shading like it had in the
start of the examination. Following three minutes, a yellow encourage started to frame. The
accelerate was seen to be a yellow, round bunch. When gauging the item after filtration, the
benzil was seen to weigh 0.47 g.
Data and Calculations:

Moles of limiting reagent
(0.500 𝑔 𝐵𝑒𝑛𝑧𝑜𝑖𝑛) 𝑥

1 𝑚𝑜𝑙𝑒 𝐵𝑒𝑛𝑧𝑜𝑖𝑛
= 0.00235 𝑚𝑜𝑙

𝑻𝒉𝒆𝒐𝒓𝒆𝒕𝒊𝒄𝒂𝒍 𝒚𝒊𝒆𝒍𝒅
(0.00235 𝑚𝑜𝑙 𝐵𝑒𝑛𝑧𝑜𝑖𝑛) 𝑥

1 𝑚𝑜𝑙𝑒 𝐵𝑒𝑛𝑧𝑜𝑖𝑛 210.23 𝑔 𝐵𝑒𝑛𝑧𝑖𝑙
1 𝑚𝑜𝑙 𝐵𝑒𝑛𝑧𝑖𝑙
1 𝑚𝑜𝑙 𝐵𝑒𝑛𝑧𝑖𝑙

= 0.49524 𝑔 𝐵𝑒𝑛𝑧𝑖𝑙

𝑷𝒆𝒓𝒄𝒆𝒏𝒕 𝒚𝒊𝒆𝒍𝒅

0.48 𝑔
𝑥 100 = 97%
0.50 𝑔
There are some conceivable mistakes that may have been in charge of the loss of 3% of the
beginning material. One wellspring of mistake may have happened through the way toward
exchanging the strong benzil from the cup to a channel paper for gauging. As the benzil set, it
was difficult to totally assemble all encourage for exchange, which brought about the departure
of a part of the strong. A way that this analysis could be improved is include a second trail so as
to keep away from earlier mistakes made in the primary preliminary.
Conclusion: The objective of the experiment was met as we were able to oxidize benzoin into
benzil in an acidic environment. Although there may have been possible sources of error, the
experiment was a success as we were able to obtain 97% of the product.


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