The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit in the United States of 5 mg/m3 (time-weighted average). In 1989, the Occupational Safety and Health Administration (OSHA) set a legal permissible exposure limit for aspirin of 5 mg/m3, but this was vacated by the AFL-CIO v. OSHA decision in 1993. Synthesis
The synthesis of aspirin is classified as an esterification reaction. Salicylic acid is treated with acetic anhydride, an acid derivative, causing a chemical reaction that turns salicylic acids hydroxyl group into an ester group (R-OH → R-OCOCH3). This process yields aspirin and acetic acid, which is considered a byproduct of this reaction. Small amounts of sulfuric acid (and occasionally phosphoric acid) are almost always used as a catalyst. This method is commonly demonstrated in undergraduate teaching labs. Reaction mechanism
Formulations containing high concentrations of aspirin often smell like vinegar because aspirin can decompose through hydrolysis in moist conditions, yielding salicylic and acetic acids. Physical properties
Aspirin, an acetyl derivative of salicylic acid, is a white, crystalline, weakly acidic substance, with a melting point of 136 °C (277 °F), and a boiling point of 140 °C (284 °F). Its acid dissociation constant (pKa) is 3.5 at 25 °C (77 °F). Polymorphism
Polymorphism, or the ability of a substance to form more than one crystal structure, is important in the development of pharmaceutical ingredients. Many drugs receive regulatory approval for only a single crystal form or polymorph. For a long time, only one crystal structure for aspirin was known.
The affected children have deletions on chromosome 11 as well as some extra genetic material from another chromosome.Ring chromosome 11- in this case genetic material from both long and short arm of the chromosome get deleted, and the remaining part joins and forms a ring like structure. Here the affected person would have symptoms associated with both 11q and 11p deletion. Genetics
If de novo deletion occurs then both the parents have normal chromosomes, and chances that another child will have the deletion decline. Very few cases have been found in which the deletion has been present in mosaic form (where some of the cells have deletion on chromosome 11 and some do not, and the symptoms are less severe) in one of the parents, which increases the risk of having another child with Jacobsen syndrome. When the childs chromosomal abnormality occurs due to one of the parents balanced translocation, the chances of another child having the abnormality is high. Diagnosis
Diagnosing Jacobsen syndrome can be difficult in some cases because it is a rare chromosomal disorder. There are a variety of tests that can be carried out, like karyotypes, cardiac echocardiograms, a renal sonogram, a platelet count, blood counts, a brain imaging study. Genetic testing can be carried out for diagnosis. Here chromosomes are stained to give a barcode like appearance and studied under the microscope, which reveals the broken and deleted genes. The condition can also be diagnosed early in the prenatal stage if there are any abnormalities seen in the ultrasound.