Medical Uses of Copper in Antiquity
Copper Applications in Health
The first recorded medical use of copper is found in the Smith
Papyrus, one of the oldest books known. The Papyrus is an Egyptian
medical text, written between 2600 and 2200 B.C., which records
the use of copper to sterilize chest wounds and to sterilize
drinking water. Other early reports of copper's medicinal uses are
found in the Ebers Papyrus, written around 1500 B.C. The Ebers
Papyrus documents medicine practiced in ancient Egypt and in other
cultures that flourished many centuries earlier. Copper compounds
were recommended for headaches, "trembling of the limbs" (perhaps
referring to epilepsy or St. Vitus' Dance), burn wounds, itching
and certain growths in the neck, some of which were probably
boils. Forms of copper used for the treatment of disease ranged
from metallic copper splinters and shavings to various naturally
occurring copper salts and oxides. A "green pigment" is spoken of
which was probably the mineral, malachite, a form of copper
carbonate. It could also have been chrysocolla, a copper silicate,
or even copper chloride, which forms on copper exposed to
seawater. In the first century A.D., Dioscorides, in his book De
Materia Medica, described a method of making another green pigment
known as verdigris by exposing metallic copper to the vapors of
boiling vinegar. In this process, blue-green copper acetate forms
on the copper surface. Verdigris and blue vitriol (copper sulfate)
were used, among other things, in remedies for eye ailments such
as bloodshot eyes, inflamed or "bleary" eyes, "fat in the eyes"
(trachoma?), and cataracts.
In the Hippocratic Collection (named for, although not entirely
written by, the Greek physician Hippocrates, 460 to 380 B.C.),
copper is recommended for the treatment of leg ulcers associated
with varicose veins. To prevent infection of fresh wounds, the
Greeks sprinkled a dry powder composed of copper oxide and copper
sulfate on the wound. Another antiseptic wound treatment at the
time was a boiled mixture of honey and red copper oxide. The
Greeks had easy access to copper since the metal was readily
available on the island of Kypros (Cyprus) from which the Latin
name for copper, cuprum, is derived.
By the time the Roman physician Aulus Cornelius Celsus began
practicing medicine, during the reign of Tiberius (14 to 37 A.D.),
copper and its derivatives had been firmly established as an
important drug in the medical practitioner's pharmacopoeia. In
Celsus' series, De Medicina, books one through six list many
purposes for which copper was used together with the preparation
and the form of copper most effective for each ailment. For the
treatment of venereal disease, for example, Celsus prescribed a
remedy consisting of pepper, myrrh, saffron, cooked antimony
sulfide, and copper oxide. These were first pounded together in
dry wine and when dry, once again pounded together in raisin wine
and heated until dry. For a non-healing chronic ulcer, treatment
consisted of copper oxide and other ingredients including enough
rose oil to give a soft consistency.
Pliny (23 to 79 A.D.) described a number of remedies involving
copper. Black copper oxide was given with honey to remove
intestinal worms. Diluted and injected as drops into nostrils, it
cleared the head and, when taken with honey or honey water, it
purged the stomach. It was given for "eye roughness," "eye pain
and mistiness," and ulceration of the mouth. It was blown into the
ears to relieve ear problems.
In the New World the Aztecs also used copper for medical purposes.
Don Francisco de Mendoza commissioned two learned Aztec Indian
physicians to record the pharmacological treatments known by the
Aztecs at the time of the Conquest. For the treatment of "Faucium
Calor" (literally, heat of the throat, or, sore throat) they
prescribed gargling with a mixture of ingredients containing
Copper was also employed in ancient India and Persia to treat lung
diseases. The tenth century book, Liber Fundamentorum
Pharmacologiae describes the use of copper compounds for medicinal
purposes in ancient Persia. Powdered malachite was sprinkled on
boils, copper acetate as well as and copper oxide were used for
diseases of the eye and for the elimination of "yellow bile."
Nomadic Mongolian tribes treated and healed ulcers of venereal
origin with orally administered copper sulfate.
Turning to more modern times, the first observation of copper's
role in the immune system was published in 1867 when it was
reported that, during the cholera epidemics in Paris of 1832, 1849
and 1852, copper workers were immune to the disease. More recently
copper's role in the immune system has been supported by
observations that individuals suffering from Menke's disease (an
inherited disease in which there is defective copper absorption
and metabolism) generally die of immune system-related phenomena
and other infections. Further, animals deficient in copper have
been shown to have increased susceptibility to bacterial pathogens
such as Salmonella and Listeria. Evidence such as this has led
researchers to suggest strongly that copper compounds not only
cure disease but also aid in the prevention of disease.
In 1885, the French physician, Luton, reported on using copper
acetate in his practice to treat arthritic patients. For external
application he made a salve of hog's lard and 30% neutral copper
acetate. For internal treatment, he used pills containing 10 mg.
of copper acetate. In 1895, Kobert published his review of the
pharmacological actions of copper compounds. Copper arsenate had
been used to treat acute and chronic diarrhea as well as dysentery
and cholera. A variety of inorganic copper preparations were found
to be effective in treating chronic adenitis, eczema, impetigo,
scorphulosis, tubercular infections, lupus, syphilis, anemias,
chorea and facial neuralgia. An organic complex of copper
developed by Bayer was shown to have curative powers in the
treatment of tuberculosis. Copper treatment for tuberculosis
continued until the 1940s, and various physicians reported on
their success in using copper preparations in intravenous
In 1939, the German physician, Werner Hangarter, noticed that
Finnish copper miners were unaffected by arthritis as long as they
worked in the mining industry. This was particularly striking
since rheumatism was a widespread disease in Finland, and workers
in other industries and other towns had more rheumatic diseases
than did the copper miners. This observation led Finnish medical
researchers plus the Germans, Hangarter and Lübke, to begin their
now classic clinical trials using an aqueous mixture of copper
chloride and sodium salicylate. They successfully treated patients
suffering from rheumatic fever, rheumatoid arthritis, neck and
back problems, as well as sciatica.
Until recently, just as in Pliny's time, the medical profession
used copper sulfate as a means to clinically induce vomiting. This
is based on the fact that one of the body's natural physiological
responses to prevent copper intoxication is vomiting. A Manual of
Pharmacology and its Applications to Therapeutics and Toxicology,
published by W. B. Saunders Company in 1957 recommends the use of
0.5 gram of copper sulfate, dissolved in a glass of water, in a
single dose, or three doses of 0.25 gram fifteen minutes apart,
for this purpose.
Since 1934, it has been known that individuals suffering from such
diseases as scarlet fever, diphtheria, tuberculosis, arthritis,
malignant tumors and lymphogranulomas exhibit an elevation of
copper in their blood plasma. Since then, the list of maladies
bringing about such elevation has been extended to fever, wounds,
ulcers, pain, seizures, cancers, carcinogenesis, diabetes,
cerebrovascular and cardiovascular diseases, and irradiation and
tissue stresses, including restricted blood flow. This suggests
that this redistribution of copper in the body has a general role
in responding to physiological, disease, or injury stress. On the
other hand, the elevation of copper in the affected organ has led
some to postulate that it was this excess of copper that caused
the disease. Nonetheless, this elevation of copper in diseased
states is suggested to account for the natural synthesis of
copper-dependent regulatory proteins and enzymes in the body
required for biochemical responses to stress. It may be that these
natural copper complexes expedite the relief of stress and the
repair of tissues. Thus, it appears that in addition to the
anti-bacterial and anti-fungal activity of inorganic copper
compounds as recognized by the ancients, metallo-organic complexes
of copper have medicinal capabilities that are fundamental to the
healing process itself.
Copper is known to be an essential element in human metabolism.
However, copper does not exist in the body in measurable amounts
in ionic form. All measurable amounts of copper in the body exist
in tissues as complexes with the organic compounds of proteins and
enzymes. Therefore, it has been concluded that copper becomes and
remains intimately involved in body processes. Some copper
complexes serve to store copper, others to transport it, and yet
others play important roles in key cellular and metabolic
processes. Studies into the roles that these copper complexes play
and the mechanisms of these roles have further confirmed that
copper enters into the prevention and control of a number of
disease states in the body. As will be discussed below, the key to
the effective use of copper-based pharmaceuticals is not the use
of inorganic compounds of copper, as used by the ancients, but
rather the use of metallo-organic complexes or chelates of copper.
The process of chelating metals allows them to be smuggled in the
transport process across the intestinal wall and thereby enter
into the mainstream of nutrient flow and usage in the body.
The first modern research on the subject of copper medicinal
substances was by Professor John R. J. Sorenson, of the University
of Arkansas for Medical Sciences, College of Pharmacy, who, in
1966, demonstrated that copper complexes have therapeutic efficacy
in the treatment of inflammatory diseases using doses that are
nontoxic. Since then, copper metallo-organic complexes have been
used to successfully treat patients with arthritic and other
chronic degenerative diseases. More than 140 copper complexes of
non-steroidal anti-inflammatory agents (aspirin and ibuprofen, for
example) have been shown to be more active than their parent
compounds. Copper aspirinate has been shown not only to be more
effective in the treatment of rheumatoid arthritis than aspirin
alone, but it has been shown to prevent or even cure the
ulceration of the stomach often associated with aspirin therapy.
Based on these experiences, the work of Professor Sorenson and
other researchers around the world has progressed into the
medicinal benefits of organic complexes of copper in a number of
disease states. This work, thus far mainly based on animal
research, has opened a whole new vista both into the understanding
of copper's many-fold role in the body and in the practicality of
using supplementary copper in the treatment of wound healing and
inflammation-related disease states. Some of these potential
Ulcer and Wound-Healing
Activities of Copper Complexes
It has been demonstrated that copper complexes such as copper
aspirinate and copper tryptophanate, markedly increase healing
rate of ulcers and wounds. For example, copper complexes heal
gastric ulcers five days sooner than other reagents. Further, it
has been shown that, whereas non-steroidal anti-inflammatory
drugs, such as ibuprofen and enefenamic acid suppress wound
healing, copper complexes of these drugs promote normal wound
healing while at the same time retaining anti-inflammatory
Anticonvulsant Activities of
The brain contains more copper than any other organ of the body
except the liver, where copper is stored for use elsewhere. This
fact suggests that copper plays a role in brain functions. With
reports of seizures in animals and humans following the protracted
consumption of copper-deficient diets, it was reasoned that copper
has a role to play in the prevention of seizures. It was
subsequently discovered that organic compounds that are not
themselves anti-convulsants exhibit anticonvulsant activity when
complexed with copper. Further, it was found that copper complexes
of all anti-epileptic drugs are more effective and less toxic than
their parent drugs.
Anticancer Activities of Copper
As early as 1912, patients in Germany were treated for facial
epithelioma with a mixture of copper chloride and lecithin.
Success of such treatment suggested that copper compounds have
anticancer activity. Work at the University of Liverpool in 1913
demonstrated that subcutaneous and intravenous injections of a
copper salt or colloidal copper softened and degenerated
carcinomas transplanted into mice. In 1930, work in France
indicated that injections of colloidal copper mobilized and
expelled tumor tissue. Recent work with mice in the USA has shown
that, indeed, treatment of solid tumors with non-toxic doses of
various organic complexes of copper markedly decreased tumor
growth and metastasis and thus increased survival rate. These
copper complexes did not kill cancer cells but caused them to
revert to normal cells.
Anticarcinogenic Activity of
Based on work in the treatment of cancers using copper complexes,
researchers have found that these same complexes may prevent or
retard the development of cancers in mice under conditions where
cancers are expected to be induced.
Radiation Protection and
Radiation Recovery of Copper Complexes
Ionizing radiation, such as that used in the treatment of cancer,
has been shown to induce massive systemic inflammation. Ideally,
such radiation-induced injury might be prevented or ameliorated by
chemical repair mechanisms in the body. Thus, pharmacological
approaches to the repair of radiation-damaged tissue are needed.
As early as 1984, copper metallo-organic complexes have been shown
to have radiation protection and radiation recovery activities.
They are capable of causing rapid recovery of immunocompetence and
recovery from radiation induced tissue changes. The mechanism of
this activity appears to be tied to the ability of certain copper
complexes to deactivate the superoxide, or "free," radicals
liberated by ionizing radiation. In addition, since radiation has
the capability of breaking the bonds of natural copper enzymes in
the body, supplementing these with non-toxic doses of
pharmaceutical copper complexes restores the lost tissue-repair
capability. Since these complexes may also have anticarcinogenic
activity, it is suggested that there would be merit in using
copper complexes in the treatment of cancer and in particular,
treating patients undergoing ionizing radiation therapy for their
cancer, accidental exposure to radiation, and astronauts
undertaking space travel.
Heart Disease and Copper
Numerous studies have drawn attention to the relationship between
copper deficiency and heart disease. First observed in rats in
1936, this effect has now been traced to both a deficiency in
copper and an imbalance in the copper-to-zinc ratio in the body.
Work by Dr. L.M. Klevay at the U.S. Department of Agriculture,
Human Nutrition Research Center in 1973 has led to the postulation
that copper has a direct effect on the control of cholesterol. In
continuing work published in 1975, he theorized that a metabolic
imbalance between zinc and copper - with more emphasis on copper
deficiency than zinc excess - is a major contributing factor to
the etiology of coronary heart disease. Subsequent work by other
investigators has shown that copper complexes also can have a
valuable role in the minimization of damage to the aorta and heart
muscle as oxygenated blood reperfuses into tissues following
myocardial infarction. This action is based on the
anti-inflammatory action of copper complexes. These and other
studies suggest the use of copper dietary supplements as a means
of preventing and controlling such diseases as atherosclerosis (a
form of arteriosclerosis), coronary heart disease, aortic
aneurysms and myocardial infarction. It has been speculated that
the reason that the heart attack rate in France is lower than in
the rest of Europe is because of the French practice of drinking
red wine. Red wine has a higher copper content than white wine
because it is prepared with the skin of the grape intact. The
copper originates in the wine from the copper fungicides used on
the grapes in the field.
Based on an abundance of historical data such as the foregoing,
many researchers anticipate that copper will become an
increasingly important component of tomorrow's medical treatments.
The historical part of this paper is based on H.H.A. Dollwet and
J.R.J. Sorenson, Historic uses of copper compounds in medicine,
Trace Elements in Medicine, Vol. 2, No. 2, 1985, pp 80 - 87.
IUPAC name -- dicopper 2-acetyloxybenzoate
Other names --
tetrakis-µ-acetylsalicylato-dicopper(II), copper(II) aspirinate,
cupric acetylsalicylate, cupric aspirinate, cupric aspirin complex
CAS number -- 23642-01-5 YesY
PubChem -- 92244
Copper(II) aspirinate is an aspirin chelate of copper(II) cations
(Cu2+). It is used to treat rheumatoid arthritis.
Molecular formula C36H28Cu2O16
Molar mass 843.69g/mol
Appearance Bright blue crystalline solid.
Melting point 248-255 °C (decomp.)
Related compounds -- Aspirin ; Other cations -- Zinc
aspirinate, Aluminium aspirinate
Except where noted otherwise, data are given for materials in
their standard state (at 25 °C, 100 kPa)
Copper aspirinate can be prepared by several methods. In one route
of preparation, an excess of acetylsalicylic acid is dissolved in
aqueous sodium carbonate. Sodium hydroxide is not suitable for
this purpose, because it will hydrolyse acetylsalicylic acid (ASA)
into salicylic acid and sodium acetate.
2 HC9H7O4 + Na2CO3 ? 2 NaC9H7O4 + CO2? + H2O
The resulting solution is then filtered to remove any undissolved
acetylsalicylic acid and is mixed with a solution containing Cu2+
cations (copper(II) sulfate is suitable), precipitating bright
blue crystals of copper aspirinate immediately. The crystals can
then be filtered from solution, washed, and dried. An excess of
acetylsalicylic acid is used in the first step, because it
eliminates the possibility of unreacted carbonate anions
precipitating the copper in this step.
4 NaC9H7O4 + 2 CuSO4 ? C36H28Cu2O16? + 2 Na2SO4
Copper aspirinate has been proven effective as a treatment for rheumatoid arthritis
studies on animal models suggest that copper aspirinate is very
promising in treating against thrombotic
and it has all the prospects of success in
becoming an antithrombotic drug that prevents and treats
thrombotic diseases in humans.
The use of copper aspirinate as a pigment in PVC and Polystyrene
has also been investigated.
1. ^ "Rheumatoid Arthritis (RA)". Copper Development Association.
2. ^ Weiping Liu,corresponding author1 Huizhou Xiong, Yikun Yang
Ling Li, Zhiqiang Shen, and Zhihe Chen (1998). "Potential
Application of Copper Aspirinate in Preventing and Treating
Thromboembolic Diseases". Met Based Drugs. (Hindawi Publishing
Corporation) 5 (3): 123–126. doi:10.1155/MBD.1998.123. PMC
2365110. PMID 18475833.
3. ^ Allan, J R; A Renton, W E Smith, D L Gerrard, J Birnie
(1991). "A Study of the Performance of Bis(acetylsalicylate)
Copper(II) and the Cobalt(II), Nickel(II) and Copper(II) Complexes
of Pyridine-3,4-dicarboxylic Acid as Colouring Materials for
Poly(vinyl chloride) and Polystyrene". Eur. Polym. J. 27 (7):
Copper Aspirinate Synthesis
is a summary of the procedure I used to make copper aspirinate. I
offer it here for informational purposes to show that copper
aspirinate can be made with commonly available materials and
equipment. A similar procedure is typically done by second-year
college chemistry students as a laboratory exercise in a setting
supervised by a professional instructor. I do NOT recommend that
people do this at home. Some aspects of these procedures are
hazardous, and the typical home kitchen simply has too many
distractions and interruptions for a student to carry out these
procedures safely. Your wife ( or mom) will also be furious if you
get copper sulfate stains on her kitchen counter!
Copper Aspirinate synthesis
Equipment and Materials required
1. Saturated copper acetate solution. See procedure below.
2. Pure aspirin crystals. See procedure below.
3. Ethanol (95%; liquor store ethanol like Everclear (190
proof, UPC 088352100036) is what was used here.
4. Vacuum filtration facilities (Büchner funnel, coarse and medium
porosity filter paper, aspirator, filter flask, seals, tubing,
clamps, stand, etc. These common lab tools are not absolutely
necessary, but can speed things up considerably.)
5. Containers for liquid such as Rubbermaid 24 fl. oz. servin'
saver tm (used here as a "beaker").
1. Add 1 fl. oz. of saturated copper acetate solution to a beaker.
2. Dissolve 1 tsp (teaspoon) pure aspirin crystals in about 1 fl.
oz. of ethanol (95%) in another beaker
3. Pour the aspirin solution into the copper acetate solution.
4. Dark blue crystals will gradually form on the sides and bottom
of the beaker. The initial layer will form immediately if the
beaker has been freshly cleaned and scoured. The layer will
gradually thicken and become bluer and darker. This process may
take several hours. The endpoint is reached when the liquid has
turned a light blue and no more blue crystals are forming on the
walls of the beaker. (You can verify the endpoint by siphoning the
clear liquid, evaporating it in a separate container, and checking
the residue. The residue should be mostly aspirin crystals.)
This procedure requires no heating. If you heat the liquid to
increase the reaction rate, be aware that aspirin can hydrolyze
into acetic and salicylic acids in a moist or liquid environment.
If that happens, the liquid will turn dark green, and the yield
of copper aspirinate will be greatly reduced.
5. Cool the mixture in a refrigerator.
6. Scrape the crystals off the sides and bottom of the beaker.
Then vacuum filter the whole mixture. (Save the first filtrate in
a separate container if you do ethanol solvent recycling.)
7. Wash the blue powder on the filter with cold distilled water.
8. Dry the powder and filter paper in an oven at about 120F. Store
the dry powder in a small dark bottle with a label identifying the
contents and the date of creation.
Substitute isopropanol (99%) for the ethanol in step #2 and
use 1/2 teaspoon, instead of 1 teaspoon, of aspirin crystals and
1/2 fl. oz. isopropanol instead of 1 fl. oz of ethanol. After
several hours of initial crystallization, add 1/2 fl. oz. of
distilled water and place the beaker in the refrigerator and wait
a few more hours for more crystals. This variation gives about the
same results as the ethanol procedure. Its advantages are that it
uses less excess aspirin and a less expensive alcohol.
Aspirin purification (kitchen
Equipment and Materials required
1. One bottle of 1000 commercial aspirin tablets (preferably the
2. A pint or two of isopropyl alcohol (99%). This is usually
available from a hardware store. Sometimes it can be found in a
drugstore (UPC: 341226909730 ) Isopropanol is extremely flammable,
so be very careful not to expose vapors to hidden or unexpected
3. A couple of gallons of deionized or distilled water.
4. Three, 24 fl. oz. wide-mouthed polypropylene containers
with covers, such as Rubbermaid servin' saver tm.
5. Oven thermometer (easily read dial type is best)
6. Modified turkey baster (see construction procedure below)
7. One kitchen (with sink, refrigerator, oven, etc)
1. Dump a few hundred aspirin tablets into a wide-mouthed
2. Add distilled water to the container and stir. This will break
up the aspirin tablets and dissolve the hydroxypropyl
methycelluose coating that is usually used to coat aspirin
tablets. Let the mixture settle for an hour or so in the
3. Siphon most of the water out with a modified turkey baster.
4. Repeat steps #2 and #3 a total of three to five
times. This will largely get rid of the methycellulose
coating, which tends to clog filters. You might not need to repeat
these steps if you use uncoated aspirin.
5. Vacuum filter the mixture from #4 and dry the powder in air.
(Caution: aspirin tends to decompose when heated in a moist
6. Add the powder to a quart container. Add about a half-cup of
isopropyl alcohol (99%). Stir. This will dissolve part, but not
all, of the aspirin. Let the mixture settle.
7. Vacuum filter the above mixture using medium porosity filter
paper. Pour the filtrate into a clear glass container for
inspection. If the filtrate is not clear, re-establish vacuum on
the filter, and filter it again. (Sometimes simply letting the
mixture settle and then siphoning the clear liquid with a turkey
baster is more effective than filtration; the latter, however, may
8. Pour the clear filtrate containing the dissolved aspirin into
the second container, cover it, and place it in the freezer
(about 5 F or so). After an hour or so the aspirin will
crystallize out of solution. Return the powder on the filter to
its original quart container.
9. After the aspirin crystals have formed, remove the
container from the freezer. Carefully decant the liquid back into
the first container that contains the impure aspirin powder. Then
scrape out the pure aspirin crystals into a third container.
10. Cover this first container (impure aspirin powder and
recovered isopropanol) and let it warm to room temperature.
Agitate it occasionally so that more aspirin will again dissolve.
11. Repeat steps 7 through 10 until you have recovered all the
aspirin, and the filter paper has only a thin layer of the
excipients (typically calcium phosphate, starch, talc, etc. These
impurities are added to the tablets to help them break up in
water). Discard the filter paper. Dump the isopropanol down the
drain, and wash it down with some tap water.
12. Using new filter paper (medium porosity), filter
any remaining isopropanol from the recovered aspirin crystals
(third container). Rinse the third container with distilled
water and wipe it dry. Dump the filtered crystals back into the
third container and cover them with cold distilled water.
Re-establish vacuum on the filter and filter the crystals again.
This will rinse off any remaining isopropanol. Discard the liquid.
(Repeat the procedure if you can still smell isopropanol on the
13. Finally, gently dry the aspirin crystals. (I dried mine in an
oven at 120 F. If you do this, BE SURE you have rinsed the
crystals well enough so that there are no isopropanol vapors
present. Isopropanol forms explosive vapors with air, and allowing
these to accumulate in a confined space is a recipe for serious
trouble. Also, aspirin tends to decompose when heated, especially
in hot water, so I use only a warm temperature setting. )
Copper acetate synthesis
Equipment and Materials required
1. Copper sulfate pentahydrate 99%. This is usually available from
a hardware store in the form of a product used to kill tree roots
in sewers and septic tanks, such as Roebic K-77.
2. Arm and Hammer Baking soda (sodium bicarbonate).
3. A couple of quarts of distilled vinegar (5% acetic acid).
4. A Pyrex casserole dish (22 x 11 x 6 cm or similar)
5. Vacuum filtration facilities.
6. Various clean, quart containers.
Preparation of filtered copper
1. Dissolve 3/4 cupful of copper sulfate crystals in about a quart
of warm distilled water.
2. Vacuum filter the solution through coarse porosity filter
paper. This will filter out suspended solids (metal flecks,
"dirt", etc.). Pour the filtrate off into a clear inspection
container. Vacuum filter the solution again with medium porosity
paper until it is clear blue. Note that the filtrate may still
contain significant impurities (lead, arsenic, cadmium, etc.) at
this point. Remember that this product is normally used in sewers.
3. Save the clear blue solution for later use.
(4. If you want higher purity copper sulfate, you can
re-crystallize it at this point.)
Preparation of sodium carbonate
1. Pour a cup full of sodium bicarbonate into a Pyrex casserole
dish. Add distilled water sufficient to dissolve it.
2. Heat the solution in an oven to about 200F. This will cause the
bicarbonate to decompose into the carbonate with the evolution of
carbon dioxide. The end result will be a solution of sodium
3. Let the solution cool to room temperature. Carbonates are
somewhat less soluble than bicarbonates; add more distilled water
if necessary to keep the material in solution.
Preparation of copper carbonate
1. In a large container, gradually combine the copper sulfate
solution with the sodium carbonate solution. A blue-green
precipitate will immediately form along with the vigorous release
of carbon dioxide. Let the precipitate settle out.
2. At this point the liquid portion will have either an excess of
sodium carbonate or of copper sulfate. If you add a drop of sodium
carbonate and see some precipitate form, then the bulk mixture
needs more sodium carbonate solution added. Likewise, if you add a
drop of copper sulfate and see a precipitate, then the bulk
mixture needs more copper sulfate solution added. Make these
adjustments as necessary until there is no longer an unambiguous
formation of the blue-green precipitate.
3. Vacuum filter the mixture with a coarse porosity paper filter.
Discard the liquid. Wash with cold distilled water and then
refilter. This will wash out any excess sodium carbonate or copper
Preparation of copper acetate
4. To a quart container, add the still moist copper carbonate
powder from the previous step. Then slowly pour vinegar into the
container. Carbon dioxide will evolve and copper acetate will
form. The solution will gradually become a deep blue color. A
blue-green precipitate may also settle to the bottom of the
5. Let the solution settle out. If there is a substantial amount
of blue-green precipitate at the bottom of the container, add more
vinegar. Try to dissolve most, but not all, of this precipitate.
An excess of vinegar is harder to remove than a little of the
6. Using coarse paper, vacuum filter the resulting copper acetate
solution. Repeat until clear. Discard the paper. Save the blue
7. Slowly evaporate the blue filtrate in a Pyrex casserole dish in
an oven (150F) for several hours. Periodically scrape down the
sides of the dish to prevent a build up of crystals. Continue the
evaporation until some blue-black crystals of copper acetate begin
to form (and do not redissolve). The mixture may also have some
blue-green "pond scum" in it too.
8. Cool and filter the dark blue solution. Store it in a clear
glass container for observation (a one quart vinegar bottle works
fine). This is the saturated copper acetate solution that will be
used to make copper aspirinate.
9. If you want to make copper acetate crystals, continue the
evaporation process until blue-black crystals form. This will
require evaporating most, but not all, of the solution. Impurities
(and excess vinegar) tend to remain in solution instead of
crystallizing out. Hence, it is necessary to discard a small
portion of the original solution. Collect the crystals on the
vacuum filter and discard the leftover liquid. Wash the blue-black
crystals with a little bit of cold distilled water. Then dry and
store them in a labeled container.
Conversion of Aspirin to
Salicylic acid (kitchen method)
1. Put about 4 tsp of pure aspirin crystals (see above) and 1/2
cup distilled water into a small, clean jar (such as one
used for canning pickles or olives).
2. Place jar on a hot pad in a shallow pan in an oven set to about
225F. Let the aspirin hydrolyze into acetic and
salicylic acids for an hour or two. (Add a little more water if
all the crystals have not dissolved in the hot liquid.)
3. Cool the liquid in the refrigerator. You should see needle-like
4. Vacuum filter and wash the crystals with cold distilled water.
This will remove acetic acid residue.
5. Dump the crystals out of the filter and air dry them. (they
usually come out as a mat of fine needles). Store in a properly
Conversion of Salicylic acid to
Phenol (carbolic acid) is an important disinfectant and germicide,
as well as an important organic reagent.
According to the Merck Index (10th ed.), salicylic acid sublimes
at 76 C, melts at 159 C, and will decompose into phenol and
carbon dioxide when rapidly heated at atmospheric pressure.
Copper Salicylate Synthesis
1. In a small custard dish, dissolve 1/4 tsp of sodium bicarbonate
(baking soda) in a few of teaspoons of distilled water.
2. Add about 1/2 tsp of the salicylic acid crystals recovered from
the conversion described above. Mixture will fizz a little. Stir
until all the crystals dissolve.
3. Test the pH. Add more salicylic acid or bicarbonate to get pH
of about 6 (slightly acid). This is now a solution of sodium
4. Add copper sulfate solution drop by drop. An ugly green
precipitate (copper salicylate) will form.
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