2-Quinolone

{{Use dmy dates|date=December 2021}}

{{Chembox

| ImageFile = 2-Quinolone.svg

| ImageSize = 180px

| ImageAlt =

| PIN = Quinolin-2(1H)-one

| OtherNames = {{bulletedlist|Carbostyril|1,2-Dihydro-2-oxoquinoline|1H-Quinolin-2-one}}

|Section1={{Chembox Identifiers

| CASNo = 59-31-4

| PubChem = 6038

| ChemSpiderID = 5816

| EINECS = 200-420-6

| UNII = 803BHY7QWU

| ChEMBL = CHEMBL186422

| ChEBI = 16365

| KEGG = C06338

| StdInChI = 1S/C9H7NO/c11-9-6-5-7-3-1-2-4-8(7)10-9/h1-6H,(H,10,11)

| StdInChIKey = LISFMEBWQUVKPJ-UHFFFAOYSA-N

| SMILES = C1=CC=C2C(=C1)C=CC(=O)N2 }}

|Section2={{Chembox Properties

| C=9|H=7|N=1|O=1

| MolarMass =

| Appearance = solid

| Density =

| MeltingPtC = 199.5

| BoilingPt =

| Solubility = }}

|Section3={{Chembox Hazards

| MainHazards =

| FlashPt =

| AutoignitionPt = }}

}}

2-Quinolone is an organic compound related structurally to quinoline. It is the majority tautomer in equilibrium with 2-quinolinol. The compound can be classified as a cyclic amide, and as such is used as an isostere for peptides and other pharmaceutically inspired targets.{{cite journal|title=The structural use of carbostyril in physiologically active substances|author=Tashima, Toshihiko|journal= Bioorganic & Medicinal Chemistry Letters|year=2015|volume=25|issue=17|pages=3415–3419|pmid=26112444| doi=10.1016/j.bmcl.2015.06.027}}{{cite web|url=https://webbook.nist.gov/cgi/cbook.cgi?ID=59-31-4&Units=SI|title=2(1H)-Quinolinone|website=NIST|access-date=August 16, 2023}} The 4-methyl-2-quinolone can be prepared by dehydration of acetoacetanilide.{{cite journal |doi=10.15227/orgsyn.024.0068 |title=4-Methylcarbostyril |journal=Organic Syntheses |date=1944 |volume=24 |page=68|first1=W. M.|last1=Lauer|first2=C. E.|last2=Kaslow }}

File:2-qionoloneEquilibrium.png 2-hydroxyquinoline (left)]]{{clear left}}

The isomer 4-quinolone is the parent of a large class of antibiotics called quinolone antibiotics. A prominent example is ciprofloxacin, a broad spectrum antibiotic commonly used for treatment of various infections such as urinary tract infections (UTIs), typhoid, meningitis, gonorrhoea, syphilis,{{Cite web |date=2023-06-20 |title=Ciprofloxacin For The Treatment Of STDs: What You Need To Know {{!}} Allo Health |url=https://www.allohealth.care/healthfeed/stds/ciprofloxacin-for-std |access-date=2024-02-08 |website=www.allohealth.care |language=en-GB}} and skin infections.{{Cite web |date=2022-12-14 |title=About ciprofloxacin |url=https://www.nhs.uk/medicines/ciprofloxacin/about-ciprofloxacin/ |access-date=2024-02-08 |website=nhs.uk |language=en}}