1-acetylnaphthalene = 1-acetonaphthone = alpha-naphthyl methyl ketone
Friedel-Crafts acylation of naphthalene with acetyl chloride catalyzed by anhydrous AlCl3.
Calculations:
AlCl3 M=133,34 g/mol
CH3COCl M=78,49 g/mol
C10H8 M=128,17 g/mol
0,50 mol:
66,67 g AlCl3 but excess was used which never hurts and is always good for such very hygroscopic chemical
39,25 g CH3COCl
64,01 g C10H8
Synthesis:
In 1 L 2-neck RBF equipped with thermometer and stir bar was added 80 g anhydrous AlCl3 (excess) quickly through wide funnel and then 100 ml of
dichlormethane. Flask was quickly stoppered to prevent air moisture entering, cooled in snow-water bath and swirled to dissolve AlCl3 (a brownish-grey
solution obtained, AlCl3 seems to be technical ??? quality, the rest of reagents were analytical grade).
Then 40,0 g acetyl chloride was quickly added at once into the cold mixture and flask again stoppered and content mixed and cooled.
The flask was put outside in winter time with a hope to perform the reaction at colder temperature than inside.
Inside lab 64,0 g naphthalene was dissolved in 100 ml dry dichloromethane in a 250 ml beaker. This dissolution was endothermic and it was necessary to
close the beaker with plastic foil and rubber gum and slightly warm the beaker. It was then transferred into pressure equalized dropping funnel.
The funnel was mounted into the neck of the reaction flask outside of lab in winter time at outside temperature 0 C. Unhappily the naphthalene started
to crystallize very soon in the cold so nothing dropped from the funnel into the reaction. This setup should be OK when doing the reaction inside lab
at 20 C, but failed in such a cold. Dropping funnel was detached and flask stoppered.
The content from dropping funnel was warmed inside lab and transferred back into the beaker.
The flask outside was magnetically stirred and small filtration glass funnel (without filter paper) was inserted into its neck to allow addition of a
solution of naphthalene and reduce air entering the reaction (prevent moisture) unlike widely opened neck without filter funnel. Solution of
naphthalene was added in small portions through the filtration funnel during 15 minutes. Significant amounts of HCl evolved which made effective
clouds of fog with air moisture. T was initially +3 C and at the end +20 C. The flask was then stoppered and stirred for 60 minutes, T fell to +5 C.
Photos of this unexpected change on the fly was not made due to stress of the chemist and all hands employed into completing the reaction. No empty
hand either time was available for making photos at this stage.
Into 1 L beaker was put 500 g of melting snow of temperature +0 C onto which was dripped 20 ml of 35% HCl and then onto the snow was slowly poured the
content from the reaction flask while stirring with magnetic stirrer and glass rod (very exothermic!).
Bottom organic layer was separated using separatory funnel and upper aqueous discarded.
It was washed with 250 ml of water and water phase again discarded, its pH was still acidic.
It was again washed with 250 ml of water and water phase again discarded, now pH of aqueous phase was almost neutral (something like 5 - 6 using
universal pH indicator paper).
It was dried with anhydrous Na2SO4 overnight in a beaker closed with plastic foil and rubber strip. The dried solution was carefully decanted into
distillation flask and the dichloromethane was distilled out.
The crude product put into lazy vacuum distillation apparatus without condenser attached to weak vacuum by water aspirator pump. Only a little of
forerun was expected to collect which could easily condense on the cold glass so messing a condenser would be contra productive. This removed
unreacted naphthalene as forerun (less than 1 gram) and the predistillation was stopped once liquid distilled which started to dissolve the crystals
of naphthalene (circa 2 ml of liquid collected).
Then it was distilled using stronger vacuum by cheap chinese 2-stage oil rotary vane vacuum pump and regular distillation setup. Fraction collected
135-142 C.
Yield 51,2 g of yellowish product.
useful info from internet:
https://www.alfa.com/en/catalog/A12918/
Formula C12H10O
Formula Weight 170.21
Melting point 9-11°
Boiling Point 302°
Density 1.120
Refractive Index 1.6280
http://www.thegoodscentscompany.com/data/rw1008371.html
alpha-naphthyl methyl ketone
oranger liquid (Givaudan)
Specific Gravity: 1.11000 to 1.11600 @ 25.00 °C.
Refractive Index: 1.62000 to 1.63000 @ 20.00 °C.
Melting Point: 33.00 to 34.00 °C. @ 760.00 mm Hg !!! this is wrong !!!
Boiling Point: 297.00 to 299.00 °C. @ 760.00 mm Hg
Odor Type: floral
sweet neroli orangeflower powdery
Thoughts and ideas.
Maybe more dichloromethane should be used which would allow the naphthalene to stay dissolved even at cold winter temperatures. When recalculating
there should be used 150 + 150 ml of dichloromethane instead of 100 + 100 ml.
Excess of AlCl3 does not hurt, in one reference they used 2-fold excess and the same yield.
The order of addition does not matter, in one reference they tried both (addition of naphthalene into complex of AlCl3 with acetyl chloride in
dichloromethane as well addition of solution of naphthalene into the complex of AlCl3 with acetyl chloride in dichloromethane) with the same results.
It seems to be more friendly not to mess dropping funnel with AlCl3 so have the AlCl3 in the flask.
Also all my few packages of analogue acetophenone are yellowish just somewhat paler, no matter new fresh chemical directly from chem supplier, the
same color as 30 years old well stored acetophenone from disassembled old labs.
The recovered dichloromethane was successfully used to dissolve the asphalt-like residue (color as well consistency) in thle distillation flask after
cooling it below b.p. of dichloromethane. Circa 50 ml of the recovered dichloromethane dissolved it in 2 hours while occasionally swirling the loosely
stoppered flask.
References:
https://shareok.org/bitstream/handle/11244/32989/Thesis-1976...
| Quote: | page 20
The acetylation reaction in dichloromethane produced alfa and beta in a 97:3 ratio.
A 500-ml, 3-necked, round-bottomed flask was equipped with a
Teflon paddle stirrer, a gas vent tube and an addition funnel which
had been modified so the added solution would drop directly into the
solution rather than down the side of the flask. The apparatus was
cooled in ice water, and a methylene chloride (100 ml) suspension of
aluminum chloride (75 g) in the flask was continuously stirred while
acetyl chloride (40.5 g) was added over a period of 5 minutes. The
addition funnel was rinsed with 10 ml of CH2cl2.
A solution of naphthalene (34 g) in CH2c12 (100 ml) was added over
a period of 15 minutes, during which the reaction mixture changed from
opaque white to yellow. The temperature was increased to 27°C, and the
mixture was stirred for 30 minutes, the color deepening to orange. The reaction mixture was worked up to yield GK-IV in 93% yield.
(!!! my note - the amount of naphthalene seems to be a mistake and should be doubled) |
https://patentimages.storage.googleapis.com/57/50/ce/95ee2bd...
| Quote: | Example 1
8 parts of acetyl chloride and 14 parts of aluminium chloride are added to 38 parts of ethylene dichloride and the mixture is stirred until the
aluminium chloride is dissolved. The solution is then added to a solution of 13 parts of naphthalene in 38 parts of ethylene dichloride, stirred at 35
C. and the mixture is stirred until no more solid separates. It is then poured into dilute hydrochloric acid and the oily layer is separated, washed
with water and distilled. 16 parts of methyl-l-naphthyl ketone of B. P. 163 C./15 mm., M. P. 9-10 C. are obtained. |
https://sci-hub.wf/10.1039/JR9490000S99
| Quote: | (2) A solution of acetyl chloride (8 g. ; 1 mol.) and aluminium chloride (14 g. ; 1 mol.) in ethylene
chloride (30 c.c.) was gradually added to a solution of naphthalene (13 g.) in ethylene chloride (30 c.c.)
at 35". A ready reaction occurred, and a solid separated. The mixture was decomposed with dilute
hydrochloric acid, and the product provided a fraction (16 g. ; b. p. 163"/15 mm. ; m. p. 9.0" and mixed
m. p. 9.5" with pure a-naphthyl methyl ketone) which was almost pure a-naphthyl methyl ketone.
Picrate analysis indicated 98% of a-ketone. A similar result was obtained when the solution of naphthalene
was gradually added to the solution of acetyl and aluminium chlorides.
(3) .Experiment (2) was repeated, using acetyl chloride (16 g. ; 2 mols.), and the product provided
a fraction (13 g. ; b. p. 165'115 mm. ; m. p. 20.0") which contained 40.5% of 8-ketone (60.5% of a-ketone
by picrate analysis).
(4) 'The above experiment was repeated with aluminium chloride (28 g.; 2 mols.). The product
provided a fraction (16 g.) which was almost pure a-ketone, m. p. 9.0" and mixed m. p. 9.5". Picrate
analysis indicated 98% of a-ketone. |
apparatus, would work if the temperature was 20 C, failed outside at 0 C, or maybe would work if more dichloromethane used for dissolving naphthalene
reagents
anhydrous AlCl3 was added into flask, then dichloromethane, dissolved, then acetyl chloride added and dissolved
   
apparatus was put outside to temperature 0 C and bath filled with snow-water, T = +3 C made naphthalene crystallize and clogged the addition funnel
(maybe using more dichloromethane would be OK and keep naphthalene dissolved or warmer environment?), so the dropping funnel was detached and glass
filtration funnel inserted through which the solution of naphthalene was added in portions using a beaker (which was not photographed due to
unexpected stress, no available hand, no available time), T of the reaction raised to 20 C during the addition and then fell to +5 C during 1 hour of
stirring
 
reaction was stopped by pouring into big beaker with 500 g of snow acidified with 20 ml of conc HCl while stirring with magnetic stirrer and glass rod
bottom organic layer was separated using separatory funnel and washed twice with 250 ml of water, pH of water from final washing was almost neutral
organic phase was dried with anhydrous Na2SO4
dichloromethane was distilled out
a forerun was removed by a predistillation in lazy setup (without condenser) using weaker vacuum given by water aspirator pump, initially a little of
naphthalene distilled (less than circa 1 g), then circa 2 ml of liquid collected which started to dissolve the layer of crystals of naphthalene
    
then the main fraction was distilled using regular vacuum distillation setup and 2-stage rotary vane oil vacuum pump, fraction collected 135-142 C
       
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
