Pyrimidine series intermediates
Pyrimidine, also known as 1,3-diazepine, is a heterocyclic compound with the chemical formula C4H4N2. Pyrimidine is formed by replacing 2 carbons in the meta-position of benzene with 2 nitrogen atoms, and is a diazine. Like pyridine, pyrimidine retains its aromaticity.
Introduction
Name: Pyrimidine
Molecular formula: C4H4N2
Molar mass: 80.09 g/mol
Density: 1.016 g/ml
Melting point: 20 - 22 °C
Boiling point: 123 - 124 °C
CAS Number: 289-95-2
EINECS Number: 206-026-0
SMILES: C1=NC=NC=C1
Application
(1) Anticancer drugs. In the selection of anticancer substances, it is crucial that there are significant differences between tumor tissues and normal tissues, that is, they have a certain ability to recognize target cells. Porphyrin compounds have special affinity for cancer cells due to their unique structures, and they can selectively stay in cancer tissues. The research of it as a localizing agent and a drug for diagnosis and treatment of cancer has already aroused great interest of chemists, medical scientists and biologists. 5-Fluorouracil is a widely used anti-metabolite and anti-tumor drug in clinic. It has inhibitory effect on various tumors. It has good clinical effect in the treatment of colorectal cancer, gastric cancer, breast cancer and other cancers. Polyesters, polyester hydrocarbons, polyester amides, deoxyribonucleic acid, furans, 5-fluorouracil derivatives linked to nitroxide radicals all have antitumor effects.
(2) Anti-AIDS drugs. Viral diseases have become one of the most harmful diseases to human beings, especially the spread of AIDS, which has aroused widespread concern. There are many kinds of anti-AIDS drugs that have been approved by the US Food Administration (FDA), many of which are nucleoside compounds. In order to reduce the toxicity of drugs and improve their efficacy, scientists have begun to turn their attention to the study of non-nucleoside compounds, and such compounds have become the focus of antiviral drug research.
Synthetic method
Pyrimidines and various substituted pyrimidines are synthesized in a variety of ways. For example, barbituric acid (2,4,6-trihydroxypyrimidine) can be obtained by the condensation of urea and diethyl malonate under the action of sodium alkoxide. Barbituric acid and phosphorus oxychloride are heated together to obtain 2,4,6-trichloropyrimidine, which reacts with sodium methoxide to obtain trimethoxypyrimidine. Chloropyrimidines react with ammonia or primary and secondary amines to generate the corresponding aminopyrimidines. The derivatives of pyrimidine, cytosine, uracil and thymine, are the constituent parts of nucleic acid and deoxynucleic acid, and the pyrimidine part in the vitamin B1 molecule is a 4-amino-2-methyl-5-pyrimidine methyl group. Many oral long-acting sulfa drugs are derivatives of pyrimidine and its isomers.
The 2,4-dichloropyrimidine is prepared by reduction reaction in the presence of palladium, magnesium oxide and activated carbon.
Pyrimidine Series Intermediates,2-Chloro-5-Methylpyrimidine,5-Bromo-2-chloropyrimidine,2 4-Dichloro-5-Methylpyrimidine Shenyang TYSChem Co., Ltd. , https://www.custchemvip.com
In the case where the pump suction pipe is air, the negative pressure (vacuum) formed during operation of the pump is used to press the water pressure lower than the suction port under the action of the atmospheric pressure, and then discharged from the discharge end of the pump. This process does not require the addition of "water diversion (guided water)". That is to say, a micro-pump with such a self-priming ability is called a "micro self-priming pump." Abbreviation: "Miniature self-priming pump" works like a miniature vacuum pump.
Micro self-priming pump features:
Micro-pumps with self-priming capability are called "micro self-priming pumps". In many cases, they are called "micro-suction pumps" for short. The meaning of self-priming is: Before the pump is pumped, the pump can automatically suck up the water without filling the pipe with water.
Micro self-priming pump parameters:
Mini Self-priming pump | Self-priming pump | Suction pump | Mini pump | High-flow micro pump | Mini pump | Low-noise micro pump self-priming, super suction, large flow, almost no noise - BSP-S series Model: BSP27250S Flow: 25L/Min Suction: 5m Pressure: 2.7 kg 1. Comprehensive advantages of self-priming pump and chemical pump, using a variety of imported corrosion-resistant materials, with acid, alkali, corrosion resistance and other properties; 2. Self-priming speed is very fast (about 1 second), strong suction power, suction stroke up to 5 meters, basically no noise. 3. Exquisite workmanship, not only self-priming, but also large flow (up to 25 liters / minute), high pressure (up to 2.7 kg), stable performance, easy installation.
pay attention:
Although some micro-pumps have self-priming ability, their maximum self-absorption height actually means that the height of the water can be lifted after adding water, which is not the same as true self-priming. For example, the target self-priming suction process is 2 meters, actually only 0.5 meters; while the miniature self-absorbing pump BSP27250S is different, its self-priming height is 5 meters, and under the condition of no diversion, it can be lower than 5 meters below the pumping end. The water is pumped up. And the volume is very small, is a true "micro self-priming pump."
Miniature self-priming pump principle: