General Description
Odorless white to light tan solid. Sinks and mixes slowly with water.
Reactivity Profile
SALICYLIC ACID(69-72-7) is a carboxylic acid. Carboxylic acids donate hydrogen ions if a base is present to accept them. They react in this way with all bases, both organic (for example, the amines) and inorganic. Their reactions with bases, called "neutralizations", are accompanied by the evolution of substantial amounts of heat. Neutralization between an acid and a base produces water plus a salt. Carboxylic acids with six or fewer carbon atoms are freely or moderately soluble in water; those with more than six carbons are slightly soluble in water. Soluble carboxylic acid dissociate to an extent in water to yield hydrogen ions. The pH of solutions of carboxylic acids is therefore less than 7.0. Many insoluble carboxylic acids react rapidly with aqueous solutions containing a chemical base and dissolve as the neutralization generates a soluble salt. Carboxylic acids in aqueous solution and liquid or molten carboxylic acids can react with active metals to form gaseous hydrogen and a metal salt. Such reactions occur in principle for solid carboxylic acids as well, but are slow if the solid acid remains dry. Even "insoluble" carboxylic acids may absorb enough water from the air and dissolve sufficiently in SALICYLIC ACID(69-72-7) to corrode or dissolve iron, steel, and aluminum parts and containers. Carboxylic acids, like other acids, react with cyanide salts to generate gaseous hydrogen cyanide. The reaction is slower for dry, solid carboxylic acids. Insoluble carboxylic acids react with solutions of cyanides to cause the release of gaseous hydrogen cyanide. Flammable and/or toxic gases and heat are generated by the reaction of carboxylic acids with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides. Carboxylic acids, especially in aqueous solution, also react with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Their reaction with carbonates and bicarbonates generates a harmless gas (carbon dioxide) but still heat. Like other organic compounds, carboxylic acids can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. A wide variety of products is possible. Like other acids, carboxylic acids may initiate polymerization reactions; like other acids, they often catalyze (increase the rate of) chemical reactions.
Air & Water Reactions
Sublimes and forms vapor or dust that may explode [USCG, 1999].
Hazard
Respiratory alkalosis, hyperkalemia,
hyperthermia, dehydration, convulsions, shock, res-
piratory paralysis, respiratory acidosis, lesions and
death from respiratory collapse; fetotoxic.
Health Hazard
Inhalation of dust irritates nose and throat. Vomiting may occur spontaneously if large amounts are swallowed. Contact with eyes causes irritation, marked pain, and corneal injury which should heal. Prolonged or repeated skin contact may cause marked irritation or even a mild burn.
Potential Exposure
Used as a topical keratolytic agent; in
manufacture of aspirin, salicylates, resins, as a dyestuff
intermediate; prevulcanization inhibitor; analytical reagent;
fungicide, antiseptic, and food preservative.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. Skin contact: remove
contaminated clothing and wash immediately with soap and
water. Seek medical attention immediately. If this chemical
has been inhaled, remove from exposure, begin rescue
breathing (using universal precautions, including resuscita-
tion mask) if breathing has stopped and CPR if heart action
has stopped. Transfer promptly to a medical facility. When
this chemical has been swallowed, get medical attention.
Give large quantities of water and induce vomiting. Do not
make an unconscious person vomit.
Incompatibilities
iron salts; lead acetate; iodine. Forms an
explosive mixture in air.
Description
Salicylic acid (from Latin salix, willow tree, from the bark of which the substance used to be obtained) is a mono hydroxy benzoic acid, a type of phenolic acid and a beta hydroxy acid. This colorless crystalline organic acid is widely used in organic synthesis and functions as a plant hormone. It is derived from the metabolism of salicin. In addition to being an important active metabolite of aspirin (acetylsalicylic acid), which acts in part as a prod rug to salicylic acid, it is probably best known for its use in anti-acne treatments. The salts and esters of salicylic acid are known as salicylates.
Chemical Properties
2-Hydroxybenzoic acid is odorless or has a slight phenolic odor with an acrid taste.
Chemical Properties
Also known as o-hydroxybenzoic acid,C6H4(OH)(COOH) is a white powder with an acrid taste that is stable in air but gradually discolored by light. Soluble in acetone, oil of turpentine, alcohol, ether,benzene; slightly soluble in water,and combustible. Derived by reacting a hot solution of sodium phenolate with carbon dioxide and acidifying the sodium salt thus formed. Used in the manufacture of aspirin and salicylates, resins, dyestuff intermediate, prevulcanization inhibitor, analytical reagent,and fungicide.
Chemical Properties
Salicylic acid has the formula C6H4(OH) COOH, where the OH group is ortho to the carboxyl group. It is also known as 2- hydroxybenzoic acid. It is poorly soluble in water (2 g / L at 20 °C). Aspirin (acetyl salicylic acid or ASA) can be prepared by the esterification of the phenolic hydroxyl group of salicylic acid with the acetyl group from acetic anhydride or acetyl chloride.
Chemical Properties
Salicylic acid is a white to tan crystalline
solid; needles.
Physical properties
Salicylic acid. Appearance: white crystalline powder. Solubility: Absolutely soluble
in ethanol, soluble in ether and chloroform, slightly soluble in water and anhydrous
ether. Stability: Stable at room temperature, discomposes into phenol and carbon
dioxide after rapidly heated. It’s partially acidic.
Aspirin. Appearance: white crystal and decomposes at 136–140? °C. Melting
point: 136?°C.?Aspirin is the acetyl derivative of salicylic acid with weak acidity. Its
acidity coefficient is 3.5 at 25?°C. Stability: Aspirin decomposes rapidly in ammonium acetate, alkali metal of acetate, carbonate, citrate or hydroxide solutions.
There are two crystal forms of aspirin including crystal form I and II.
Occurrence
Unripe fruits and vegetables are natural sources of salicylic acid, particularly blackberries, blueberries, cantaloupes, dates, raisins, kiwi fruits, guavas, apricots, green pepper, olives, tomatoes, radish and chicory; also mushrooms. Some herbs and spices contain quite high amounts, although meat, poultry, fish, eggs and dairy products all have little to no salicylates. Of the legumes, seeds, nuts, and cereals, only almonds, water chestnuts and peanuts have significant amounts.
History
The Greek physician Hippocrates wrote in the 5th century BC about a bitter powder extracted from willow bark that could ease aches and pains and reduce fevers . This remedy was also mentioned in texts from ancient Sumer , Lebanon , and As syria .
The active extract of the bark, called salicin, after the Latin name for the white willow (Salix alba), was isolated and named by the German chemist Johann Andreas Buchner in 1826. Raffaele Piria, an Italian chemist was able to convert the substance into a sugar and a second component, which on oxidation becomes salicylic acid.
Salicylic acid was also isolated from the herb meadowsweet (Filipendula ulmaria, formerly classified as Spiraea ulmaria) by German researchers in 1839. While their extract was somewhat effective, it also caused digestive problems such as gastric irritation, bleeding, diarrhea, and even death when consumed in high doses.
Definition
A crystalline
aromatic carboxylic acid. It is used in medicines, as an antiseptic, and in the manufacture of azo dyes. Its ethanoyl (acetyl)
ester is aspirin. See aspirin; methyl salicylate.
Definition
ChEBI: A monohydroxybenzoic acid that is benzoic acid with a hydroxy group at the ortho position. It is obtained from the bark of the white willow and wintergreen leaves.
Indications
Salicylic acid is a β-hydroxy acid that penetrates into the sebaceous gland
and has comedolytic and anti-inflammatory properties. It can be used as an
adjunctive therapy and is found in cleansers, toners, masks, and peels.
Salicylic acid is keratolytic and at concentrations between 3% and 6% causes softening
of the horny layers and shedding of scales. It produces this desquamation
by solubilizing the intercellular cement and enhances the shedding of corneocytes
by decreasing cell-to-cell cohesion. In concentrations >6%, it can be destructive to
tissue. Application of large amounts of the higher concentration of salicylic acid can
also result in systemic toxicity. Salicylic acid is used in the treatment of superficial
fungal infections, acne, psoriasis, seborrheic dermatitis, warts, and other scaling dermatoses.
When it is combined with sulfur, some believe that a synergistic keratolytic
effect is produced. Common preparations include a 3% and 6% ointment with
equal concentration of sulfur; 6% propylene glycol solution (Keralyt); 5% to 20%
with equal parts of lactic acid in flexible collodion for warts (Duofilm, Occlusal);
in a cream base at any concentration for keratolytic effects; as a 60% ointment for
plantar warts; and in a 40% plaster on velvet cloth for the treatment of calluses and
warts (40% salicylic acid plaster).
Preparation
Prepared by heating sodium phenolate with carbon dioxide under pressure
Production Methods
Salicylic acid is biosynthesized from the amino acid phenylalanine. In Arabidopsis thaliana it can also be synthesized via a phenylalanine - independent pathway.
Sodium salicylate is commercially prepared by treating sodium phenolate ( the sodium salt of phenol ) with carbon dioxide at high pressure (100 atm ) and high temperature (390K) -a method known as the Kolbe-Schmitt reaction. Acidification of the product with sulfuric acid gives salicylic acid :
It can also be prepared by the hydrolysis of aspirin (acetylsalicylic acid) or methyl salicylate (oil of winter green) with a strong acid or base.
Production Methods
Salicylic acid may be obtained (1) from oil of wintergreen, which contains methyl salicylate, or (2) by heating dry sodium phenate C6H5ONa plus carbon dioxide under pressure at 130 °C (266 °F) and recovering from the resulting sodium salicylate by adding dilute sulfuric acid.
Brand name
Advanced Pain Relief Callus Removers (Schering-Plough HealthCare); Advanced Pain Relief Corn Removers (Schering-Plough HealthCare); Clear Away Wart Remover (Schering-Plough HealthCare); Compound W (Whitehall-Robins); Dr. Scholl’s Callus Removers (Schering-Plough HealthCare); Dr. Scholl’s Corn Removers (Schering-Plough HealthCare); Dr. Scholl’s Wart Remover Kit (Schering-Plough HealthCare); Duofilm Wart Remover (Schering-Plough HealthCare); Duoplant (Stiefel); Freezone (Whitehall-Robins); Ionil (Galderma); Ionil-Plus (Galderma); Salicylic Acid Soap (Stiefel); Saligel (Stiefel); Stri-Dex (Sterling Health U.S.A.).
Biochem/physiol Actions
Salicylic acid (SA) plays a major role in the growth and development of plants. It also plays a role in endogenous signaling for plant disease resistance. SA is also involved in mediating thermogenesis and symptom development.
Mechanism of action
Salicylic acid has been shown to work through several different pathways. It produces its anti - inflammatory effects via suppressing the activity of cyclo oxygenase (COX), an enzyme which is responsible for the production of pro - inflammatory mediators such as the prostaglandins. Notably, it does this not by direct inhibition of COX, unlike most other non-steroidal anti-inflammatory drugs (NSAIDs), but instead by suppression of the expression of the enzyme (via a yet-un elucidated mechanism) . Salicylic acid has also been shown to activate adenosine monophosphate-activated protein kinase (AMPK), and it is thought that this action may play a role in the anticancer effects of the compound and its prod rugs aspirin and salsalate. In addition, the anti diabetic effects of salicylic acid are likely mediated by AMPK activation primarily through allosteric conformational change that increases levels of phosphorylation. Salicylic acid also uncouples oxidative phosphorylation which leads to increased ADP:ATP and AMP:ATP ratios in the cell. Consequently, salicylic acid may alter AMPK activity and subsequently exert its anti-diabetic properties through altered energy status of the cell. Even in AMPK knock - out mice, however, there is an anti-diabetic effect demonstrating that there is at least one additional, yet - unidentified action of the compound.
Pharmacology
Aspirin is a nonsteroidal anti-inflammatory drug (NSAID). The main pharmacological effect is to inhibit prostaglandin metabolism and thromboxane synthesis by
inhibiting prostaglandin metabolism-required cyclooxygenase, via irreversible acetylation of 530 serine residues in the hydroxyl of COX-1 polypeptide chain,
which results in COX-1 inactivation, blocks the conversion of arachidonic acid into
thromboxane A2 pathway and then inhibits the platelet aggregation.
Prostaglandin is a hormone produced locally in the body. It can pass the pain to
the brain, regulate body temperature in the hypothalamus and cause inflammation.
Inhibition of prostaglandin synthesis can have antipyretic, analgesic, antiinflammatory and antirheumatic effects. The adverse effects of aspirin are mainly
gastrointestinal symptoms such as nausea, vomiting, upper abdominal discomfort or
pain. It can also cause allergic reactions, cardiotoxicity, liver and kidney damage
and Wright’s syndrome. In addition, high doses of aspirin can cause salicylic acid
reactions such as headache, dizziness, tinnitus, hearing loss and other central nervous system symptoms.
Clinical Use
The clinical application of aspirin varies with the therapeutic dose. Low-dose aspirin (75–300?mg/day) has antiplatelet aggregation effect and can be used to prevent
and treat the coronary and cerebrovascular thrombosis and other postoperative
thrombosis. The middle dose of aspirin (0.5–3? g/day) has antipyretic analgesic
effects, so it is commonly used in the treatment of fever, headache, toothache, neuralgia, muscle pain and menstrual pain. High doses of aspirin (more than 4?g/day)
have anti-inflammatory and antirheumatic effects for the treatment of acute rheumatic fever and rheumatoid arthritis. In addition, aspirin is used for the treatment of
skin and mucous membrane lymphadenopathy (Kawasaki disease) in paediatric.
Side effects
Salicylic acid's side
effects include erythema and scaling.
Veterinary Drugs and Treatments
Often combined with sulfur, salicylic acid shampoos are often employed to treat patients with seborrheic disorders (seborrhea sicca and
oleosa) exhibiting mild to moderate scaling, with mild waxy and keratinous debris. In higher concentrations, topicals such as Kerasolv?
Gel (6.6% salicylic acid) can be used to remove localized excessive tissues associated with hyperkeratotic disorders, such as calluses and
idiopathic thickening of the planum nasale and footpads.
Salicylic acid has mildly antipruritic, antibacterial (bacteriostatic), keratoplastic and keratolytic actions. Lower concentrations are
primarily keratoplastic and higher concentrations, keratolytic. Salicylic acid lowers skin pH, increases corneocyte hydration and dissolves
the intercellular binder between corneocytes. Salicylic acid and sulfur are thought to be synergistic in their keratolytic actions.
storage
4°C, protect from light
Purification Methods
It has been purified by steam distillation, by recrystallisation from H2O (solubility is 0.22% at room temperature and 6.7% at 100o), absolute MeOH, or cyclohexane and by sublimation in a vacuum at 76o. The acid chloride (needles) has m 19-19.5o, b 92o/15mm, the amide has m 133o (yellow needles from H2O), the O-acetyl derivative has m 135o (rapid heating and the liquid resolidifies at 118o), and the O-benzoyl derivative has m 132o (aqueous EtOH). [IR: Hales et al. J Chem Soc 3145 1954, Bergmann et al. J Chem Soc 2351 1950]. [Beilstein 10 IV 125.]
Plant hormone
Salicylic acid (SA) is a phenolic phytohormone and is found in plants with roles in plant growth and development, photosynthesis, transpiration, ion uptake and transport. SA also induces specific changes in leaf anatomy and chloroplast structure. SA is involved in endogenous signaling, mediating in plant defense against pathogens. It plays a role in the resistance to pathogens by inducing the production of pathogenesis-related proteins . It is involved in the systemic acquired resistance (SAR) in which a pathogenic attack on one part of the plant induces resistance in other parts. The signal can also move to nearby plants by salicylic acid being converted to the volatile ester, methyl salicylate.
