It is better to analyze the synthesis here in more detail. To avoid work with sulfuric acid, it is better to find intermediate 1-methyl-1H-indazole-carboxylate (cas 43120-28-1). Then the first reaction, with which we will deal - it is an alkylation of an indazol derivative. Alkylation occurs in the polar aprotic solvent (THF, DMF) in the presence of a strong base (sodium hydride. sodium or potassium methylat, ethylate or butylate, etc). This reaction is very sensitive to water (fire hazard!). The main rule is ideally dry equipment and perfectly dry solvents. Equipment we can dry with a directional heat (construction dryer), solvents drain watering agents (calcium chloride, magnesium sulfate, etc). The room should not be with high humidity, it may be critical for self-ignition reaction. Any glass used, scoop, a spoon must be perfectly dry, not a single drop of water. The reaction itself should pass with strong cooling (Ice-Water bath) with the same purpose - to keep the reaction from burning. If it lights up, then it looks like a volcanic eruption. It is necessary to have a fire extinguisher near and the fire fabric to overlap the oxygen access to the flame. When we created ideal conditions (dried equipment, solvents, room) We are ready to start the reaction. I love to use DMF and sodium hydride in mineral oil. First, we prepare an 1-methyl-1H-indazole-carboxylate solution in DMF, after that, cool in ice-water bath. The volume of the flask depends on the scaling of the reaction. The shape of the flask we can use as a round bottom (if we have a tripod for holding the flasks), flat-bottomed or erlenmeyer, if she suddenly turned out to be at hand. In the round bottom flask, cooling is much more efficient for the entire volume. Without a tripod, we can cool and mix the mixture manually. After we cool the flask, we begin with small portions to sprinkle sodium hydride to the solution, thoroughly stirring after each addition, not removing from cooling. At 10 g 1-methyl-1H-indazole-carboxylate we need 2,4 g commercially available sodum hydride 60% in mineral oil. After adding the entire sodium hydride, we remove the ice-water bath and stirring at room temperature for an hour or more. We can mix both manually and with a magnetic stirrer. After this time, we cool the flask in the freshly prepared ice-water bath. Now we require 5-bromo-1-pentene, cas 1119-51-3 (12 g for 10 g indazole derivative). It must be added dropwise with constant stirring and cooling. To accomplish this, we can use a syringe (making all manually) or we can use a drip funnel, fixed on a tripod over the flask. After all the addition, remove the cooling and mix the night (on a magnetic stirrer or manually flask if there are no sitrrer). After time, we pour cold water into the flask. The amount of water is at least double the amount of DMF, better than 3-4 equivalents or more. The initial amount of DMF proceeds from what amount an indazole derivative can be dissolved. Optimally, it is 3 equivalent conditionally (30 ml at 10 g is minimal). Next, after mixing the reaction mixture with water, we are extracted with ethyl acetate. The number of ethyl acetate is at least 30% of the total volume of the mixture. As a result, the minimum amount of flasks for 10 g: 10 g indazole+30 ml DFM+10 ml pentene, 60 ml water, 30ml EtOAc = 150 ml volume of the flask is minimal for 10 g indazole derivative. Ethyl acetate can be washed with water, saturated with salt, dry magnesium sulfate from water residues, and evaporate the solvent, to obtain a derivative one as an oil. Regarding distillation and its variants will be created a separate topic. If you need any refinement for equipment for this stage, then I am waiting for questions.
I have brought many full set from china and got very unreliable.. thankyou for your time today
