IUPAC Name: (2S)-2-[[4-[(2,4-Diaminopteridin-6-yl)methyl-methylamino]benzoyl]amino]pentanedioicacid
Following is the structure of Methotrexate (CAS NO.59-05-2):
                          
Empirical Formula: C₂₀H₂₂N₈O₅ 
Molecular Weight: 454.44 g/mol 
EINECS: 200-413-8
Index of Refraction: 1.737
Molar Refractivity: 118.97 cm³
Molar Volume: 295.6 cm³
Density: 1.536 g/cm³
Melting point: 195 °C 
storage temp.: −20 °C
Polarizability: 47.16 10^-24cm³
Surface Tension: 96.4 dyne/cm 
Water solubility: Insoluble. <0.1 g/100 mL at 19 °C
Appearance of Methotrexate (CAS NO.59-05-2): Yellow Crystaline Powder
Stability: Stable, but light sensitive and hygroscopic. Incompatible with strong acids, strong oxidizing agents. Store at -15C or below.
Product Categories: Aromatic Esters; Antibiotics for Research and Experimental Use; Antitumors for Research and Experimental Use; Biochemistry; Others (Antibiotics for Research and Experimental Use);Intermediates & Fine Chemicals; Pharmaceuticals; API's; Antitumour
Canonical SMILES: CN(CC1=CN=C2C(=N1)C(=NC(=N2)N)N)C3=CC=C(C=C3)C(=O)NC(CCC(=O)O)C(=O)O
Isomeric SMILES: CN(CC1=CN=C2C(=N1)C(=NC(=N2)N)N)C3=CC=C(C=C3)C(=O)N[C@@H](CCC(=O)O)C(=O)O
InChI: InChI=1S/C20H22N8O5/c1-28(9-11-8-23-17-15(24-11)16(21)26-20(22)27-17)12-4-2-10(3-5-12)18(31)25-13(19(32)33)6-7-14(29)30/h2-5,8,13H,6-7,9H2,1H3,(H,25,31)(H,29,30)(H,32,33)(H4,21,22,23,26,27)/t13-/m0/s1
InChIKey: FBOZXECLQNJBKD-ZDUSSCGKSA-N

  Methotrexate originated in the 1940s when Dr. Sidney Farber at Children's Hospital Boston was testing the effects of folic acid on acute leukemic (severe blood cancer) children.

Dr. Subbarao, who also happened to be the head of the team which had earlier synthesized folic acid (1946) readily synthesized this anti-folate and handed it over to Dr. Farber, who in turn administered it to a small group of very ill leukemic children.

The remarkable clinical improvement that was observed in these patients heralded the era of cancer chemotherapy in modern medicine. This was reported by Dr. S. Farber in the June 3rd, 1948 issue of NEJM.

In 1950 Dr. Farber founded in Boston the world's first Cancer Research Center. Methotrexate gained Food and Drug Administration (FDA) approval as an oncology drug in 1953.

 Methotrexate (CAS NO.59-05-2) was originally used as part of combination chemotherapy regimens to treat many kinds of cancers. It is commonly used (generally in combination with misoprostol) to terminate early pregnancies (i.e. as an abortifacient). It is also used to treat ectopic pregnancies. It has come into use as a treatment for some autoimmune diseases, including polymyositis, dermatomyositis, inclusion body myositis, ankylosing spondylitis, Crohn's disease, psoriasis, pustular psoriasis, psoriatic arthritis, rheumatoid arthritis, and scleroderma (see disease-modifying antirheumatic drugs). It also can be used as a antineoplastic and antirheumatic.Or can be used as a folic Acid antagonist.

IARC Cancer Review: Group 3 IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 7 ,1987,p. 241.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Animal Inadequate Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 26 ,1981,p. 267.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) ; Human Inadequate Evidence IMEMDT    IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man . 26 ,1981,p. 267.(World Health Organization, Internation Agency for Research on Cancer,Lyon, France.: ) (Single copies can be ordered from WHO Publications Centre U.S.A., 49 Sheridan Avenue, Albany, NY 12210) . NCI Carcinogenesis Studies (ipr); No Evidence: mouse, rat CANCAR    Cancer. 40 (1977),1935. . Reported in EPA TSCA Inventory.

A human poison by intraspinal route. Poison experimentally by ingestion, intravenous, subcutaneous, and intraperitoneal routes. Human teratogenic effects by ingestion: developmental abnormalities of the craniofacial area and the musculoskeletal system. Human systemic effects by multiple routes: thrombocytopenia (decrease in the number of blood platelets), bone marrow changes, other blood changes, cerebral spinal fluid effects, eye effects, blood pressure lowering, cough, dyspnea, fibrosis (pneumoconiosis), cyanosis, gastrointestinal effects, fatty liver degeneration, hepatitis, impairment of liver function tests, other liver changes, fever, effects on inflammation or mediation of inflammation, leukopenia. Human mutation data reported. Experimental reproductive effects. A human eye irritant. Questionable human carcinogen producing leukemia, Hodgkin's disease, and skin tumors. An FDA proprietary drug. A chemotherapeutic agent. When heated to decomposition it emits toxic fumes including NOx.
Hazard Codes: T
Risk Statements: 61-25-36/38-46 
R61: May cause harm to the unborn child. 
R25: Toxic if swallowed. 
R36/38: Irritating to eyes and skin. 
R46: May cause heritable genetic damage.
Safety Statements: 53-26-36/37-45-36/37/39
S53: Avoid exposure - obtain special instructions before use. 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36/37: Wear suitable protective clothing and gloves. 
S45: In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) 
S36/37/39: Wear suitable protective clothing, gloves and eye/face protection.
RIDADR: UN 2811 6.1/PG 3
WGK Germany: 3
RTECS: MA1225000
F: 3-8-10
HazardClass: 6.1(b)
PackingGroup: III

 Methotrexate , its cas register number 59-05-2. It also can be called  4-Amino-10-methylfolic acid ; 4-Amino-N(sup 10)-methylpteroylglutamic acid ; 4-Aminomethylpteroylglutamic acid ; A-Methopterin ; A-Methpterin ; Abitrexate ; Amethopterin ; Amethopterin L- ; Antifolan ; Brimexate ; Emtexate ; Emthexat ; Emthexate ; Farmitrexat ; Fauldexato ; Folex ; Folex PFS ; Folex-Pfs ; Kyselina 4-amino-N(sup 10)-methylpteroylglutamova ; Kyselina 4-amino-N(sup 10)-methylpteroylglutamova [Czech] ; Kyselina N-(p-((2,4-diamino-6-pteridinylmethyl)methylamino)benzoyl)-L-glutamova ; Kyselina N-(p-((2,4-diamino-6-pteridinylmethyl)methylamino)benzoyl)-L-glutamova [Czech] ; L-(+)-N-(p-(((2,4-Diamino-6-pteridinyl)methyl)methylamino)benzoyl)glutamic acid ; L-Glutamic acid, N-(4-(((2,4-diamino-6-pteridinyl)methyl) ethylamino)benzoyl)- ; Lantarel ; Ledertrexate ; Lumexon ; Maxtrex ; Metatrexan ; Methoblastin ; Methotrexat-Ebewe ; Methotrexate ; Methotrexate LPF ; Methotrexate, L- ; Methotrexatum ; Methotrexatum [INN-Latin] ; Methylaminopterin ; Methylaminopterinum ; Metotressato ; Metotressato [DCIT] ; Metotrexato ; Metotrexato [INN-Spanish] ; Metrotex ; Mexate ; Mexate-AQ ; N-(4-(((2,4-Diamino-6-pteridinyl)methyl)methylamino)benzoyl)-L-glutamicacid ; N-(p-(((2,4-Diamino-6-pteridinyl)methyl)methylamino)benzoyl)-L-(+)-glutamic acid ; N-(p-(((2,4-Diamino-6-pteridyl)methyl)methylamino)benzoyl)glutamic acid ; N-Bismethylpteroylglutamic acid ; Novatrex ; Rheumatrex ; Texate ; Tremetex ; Trexeron ; Trixilem ; UNII-YL5FZ2Y5U1 ; and alpha-Methopterin . 
Its classification code are Abortifacient Agents; Abortifacient agents, nonsteroidal; Agricultural Chemical; Antimetabolites; Antimetabolites, antineoplastic; Antineoplastic; Antineoplastic Agents; Antirheumatic agents; Dermatologic agents; Drug / Therapeutic Agent; Enzyme inhibitors; Folic acid antagonists; Human Data; Immunologic Factors; Immunosuppressive agents; Insecticide; Mutation data; Noxae; Nucleic acid synthesis inhibitors; Reproductive Control Agents; Reproductive Effect; Skin / Eye Irritant and Tumor data.