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Author: Subject: 1-naphthoic acid from 1-acetylnaphthalene (chloroform reaction)
Fery
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[*] posted on 10-1-2025 at 09:45
1-naphthoic acid from 1-acetylnaphthalene (chloroform reaction)


I did the chloroform reaction with the 1-acetonaphthone which I synthesized from naphthalene and acetyl chloride catalyzed by AlCl3 (Friedel-Crafts) some time ago.

ideal reaction:
C10H7-CO-CH3 + 3 OCl- -> C10H7COO- + 2 OH- + CHCl3
(but in the experiment it was slightly different and required additional NaOH)

calculations:

50 mmol 1-acetonaphthone =170,2 g/mol * 0,05 mol = 8,5 g

0,15 mol NaOCl 74,44 g/mol * 0,15 mol = 11,2 g
using 12% NaOCl 11,2 / 0,12 = 93,3 g

0,050 mol NaOH (M = 40g/mol) = 2,0 g

these amounts were used:
8,5 g 1-acetonaphthone 50 mmol
100 ml NaOCl containing 24% chlorine
3,0 g NaOH in 5 ml H2O cooled to RT after dissolution (very exothermic) 75 mmol

procedure:
Into 250 ml RBF equipped with thermometer and reflux condenser was put 8,5 g 1-acetylnaphthalene, then 100 ml 12% NaOCl (3-5 years old, stored in +4 C in fridge) and 3,0 g NaOH dissolved in 5 ml of water and cooled down (exothermic). Reaction was magnetically stirred at high RPM (poor solubility of the substrate) and heated to +60 C. Smell of chloroform observed after 30 minutes from the top of condenser but later wanished and the substrate was still present and not fully reacted. After 1 hour 50 ml of NaOCl added, the substrate still present after some time. After another 1 hour 50 ml of NaOCl added with 3 g of NaOH in 5 ml water. Temperature was 65 C. T raised to 75 C and reaction was stirred for another 1 hour. Now the substrate was fully reacted, the mixture clear, all chloroform hydrolyzed with NaOH.
Reaction cooled to room temperature, 2 ml acetone added to destroy excess of NaOCl, gravity filtered, strongly alkaline reaction by universal pH indicator.

30 ml 35% HCl added dropwise while stirring, first 10 ml just neutralized excess of alkaline, next 10 ml precipitated the product, last 10 ml looked like just evolution of ClO2 from NaClO3 (old NaOCl used and disproportionation reaction by heating 3 NaOCl -> NaClO3 + 2 NaCl).

Cooled down on snow.
Vacuum filtered on Buchner funnel, washed with 50 ml of ice cold water.

Wet cake 80 g (!!! massive amount of water and some dissolved NaCl present !!!)

2x suspended in 200 ml water, magnetically stirred for 1 hour and filtered on Buchner funnel.

7,3 g air dried crude product.
C11H8O2 M=172,2 g.mol-1
50 mmol = 8,6 g (100%)
7,3 g = 85%

Crystallized from 85 %wt isopropanol 70 ml (product fully dissolved, maybe even less could be enough? and certainly more water present = less concentrated IPA), gravity filtered into clean flask on heating stove plate (to reduce loses by crystallization on cooling down in filtration funnel). Extra 10 ml of boiling solvent used for washing flask and little of crystals on filter paper (due to slight cooling down on filtering), on the other hand some solvent boiled out during the filtration as the flask was on heating plate and solvent boiling and heating the filtration funnel positioned above.
Supersaturation on cooling down observed, a little of solution was taken onto tip of glass rod, evaporated and the solution inoculated. Cooled down to 0 C.

Crystals vacuum filtered on sinter, washed with cca 10 ml of 85 % wt cold (0 C) IPA on sinter, air dried.
yield 3,0 g (1st crop)
m.p. 161-162 C, (lit 161 C)

Mother liquor boiled down to 15 ml for second crop crystallization
second crop 2,3 g
m.p. 160,5 - 161,5 C

total 3,0 + 2,3 = 5,3 g (yield 61%)

Water is not good for recryst, from 150 ml boiling water only 0,25 g of product obtained. 85 wt% isopropanol was just an attempt to find a suitable solvent, evidently less concentrated IPA could be better and should be tried.

cv2p0425.pdf
They recrystallized about 130 g of 1-naphthoic acid from 400 ml of toluene.

CV2P0428.pdf
they crystallized about 85 g of 2-naphthoic acid from 600 ml of 95% ethanol

Due to prolonged reaction time caused by poor solubility of organic reactant, all the chloforom hydrolyzed, its scent was present during early stages of reaction but was completely lost later.
note HCCl3 was destroyed by NaOH, no chloroform obtained as it hydrolyzed with excess of NaOH
HCCl3 + 4 NaOH -> HCOONa + 3 NaCl + 2 H2O

another side reaction when heating NaOCl:
3 NaOCl -> NaClO3 + 2 NaCl

partial reaction:
C10H7-CO-CH3 + 3 NaOCl -> C10H7COONa + 2 NaOH + CHCl3

total reaction:
C10H7-CO-CH3 + 3 NaOCl + 2 NaOH -> C10H7COONa + HCOONa + 3 NaCl + 2 H2O
= more NaOH had to be used since beginning of the reaction, not only 3,0 grams but rather more than 4,0 grams.

substances poorly water soluble or with high melting point (above +60 C) are dissolved in a little of methanol prior the reaction, then NaOCl reacts with methanol into methyl hypochlorite which is more organic friendly than water + NaOCl


https://orgsyn.org/demo.aspx?prep=cv2p0425
Attachment: cv2p0425.pdf (335kB)
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https://orgsyn.org/demo.aspx?prep=CV2P0428
Attachment: CV2P0428.pdf (335kB)
This file has been downloaded 38 times

https://sci-hub.se/10.1021/ja01359a506
Attachment: vanarendonk1931.pdf (183kB)
This file has been downloaded 33 times

https://chemlab.truman.edu/files/2015/07/Multi-1-Oxidation-o...
Attachment: Multi-1-Oxidation-of-Acetophenone-2017.pdf (83kB)
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https://www.studocu.com/en-us/document/colorado-state-univer...

solubility in 9 solvents, a nice graph at page 14:
https://sci-hub.se/10.1016/j.molliq.2018.09.114
Attachment: fan2019.pdf (1MB)
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Fery
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Posts: 1044
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline


[*] posted on 10-1-2025 at 10:05


reactants in apparatus

IMG_20241206_140305_1.jpg - 64kB



rapid magnetic stirring to overcome the poor solubility of the organic substrate in the solution of NaOCl

IMG_20241206_140504_0.jpg - 63kB



reaction heated to +60 C

IMG_20241206_145317_9.jpg - 57kB



extra 50 ml of NaOCl and more time for the reaction, still not done

IMG_20241206_161812_6.jpg - 48kB IMG_20241206_161907_0.jpg - 57kB



some time later, the reaction still not done, unreacted substrate floating on top after temporarily stopping stirring

IMG_20241206_183056_9.jpg - 77kB



extra 50 ml of NaOCl and extra NaOH added (the extra NaOH had to be added earlier = from the beginning of the reaction, but I did not know that all the chloroform hydrolyzed which required extra NaOH), magnetic stirring, an emulsion visible = the reaction not yet fully done

IMG_20241206_192855_6.jpg - 54kB



after 1 hour the reaction finally done, resulting clear solution, only microdroplets of impurities on the top

IMG_20241206_205032_9.jpg - 58kB



little of acetone added to destroy excess NaOCl, gravity filtered, impurities trapped on filter paper and clear solution obtained

IMG_20241206_213750_7.jpg - 52kB IMG_20241206_213759_3.jpg - 57kB



acidified with HCl and filtered on Buchner funnel

IMG_20241207_052135_3.jpg - 53kB



wet cake trapped a lot of water with dissolved NaCl, 2x suspended and stirred in water and filtered


recrystallization from 85 %wt isopropanol (I recommend less concentrated IPA, but can't estimate how much diluted IPA)

IMG_20250102_154912_3.jpg - 77kB IMG_20250102_161117_4.jpg - 58kB



vacuum filtered on sinter (1st crop)

IMG_20250107_153748_9.jpg - 43kB IMG_20250107_154548_2.jpg - 53kB



dried product, I do not know whether it should be yellowish or it is not pure enough, but m.p. seems like it is quite pure

IMG_20250108_102401_0.jpg - 115kB IMG_20250108_134024_2.jpg - 112kB
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