Substitution in the pyrazole series. Halogen derivatives of 3,5-dimethylpyrazole was written by Morgan, G. T.;Ackerman, Isidore. And the article was included in Journal of the Chemical Society, Transactions in 1923.Name: 4-Chloro-3,5-dimethyl-1H-pyrazole This article mentions the following:
The diazo derivatives have been studied as a means of preparing the substitution derivatives of 3,5-dimethylpyrazole (I), but the results showed that the yields were less than by direct halogenation. Iodination occurs much more readily than in the C6H6 series. The 4-NO2 derivative is best prepared by adding 6 cc. HNO3 (d. 1.42) to 10 cc. concentrated H2SO4 containing 5 g. I at 0鎺? adding 20 cc. additional H2SO4, allowing to stand overnight and then heating 3-4 hrs. at 100鎺? The reduction to the 4-NH2 derivative is best carried out in moist Et2O with Al-Hg, the yield being 85%. Benzylidene derivative, m. 139-40鎺? o-Nitrobenzylidene derivative, greenish yellow turning reddish brown on exposure to light and air, m. 101鎺? m-isomer, light yellow, m. 236鎺? p-isomer, golden yellow, m. 198鎺? Aqueous HCHO gives the complex [HOCH2N.N:CMe.C(N:CH2):CMe]x, does not m. 300鎺? The diazonium chloride condenses with 灏?diketones and 灏?keto esters in the presence of aqueous AcONa. 4-Azoacetylacetone derivative, golden yellow, m. 184鎺?(decomposition). 4-Azobenzoylacetone derivative, light yellow, m. 169-70鎺?(decomposition). Et 3,5-dimethylpyrazole-4-azoacetoacetate, orange-yellow, m. 157鎺? These derivatives gave red Na salts which developed intense red colors with FeCl3. 4-Iodo-3,5-dimethylpyrazole (II), m. 137鎺? is obtained in 60% yield from boiling aqueous KI and the diazonium chloride, or in quant. yield by heating I, I in KI, AcONa and H2O. Ac derivative, m. 62.5-3.5鎺? Bz derivative, m. 82鎺? Chloroaurate, orange-yellow, m. 174鎺? Chloroplatinate, light orange, m. 215-20鎺? Dichloride, yellow, m. 85-88鎺? by passing dry Cl into II in CHCl3; it is very volatile at the ordinary temperature and the vapor is lachrymatory. The action of dilute aqueous NaOH is complicated and destructive and an iodoso derivative could not be isolated. Dibromide, brick-red, m. 78-81鎺? this also is volatile and lachrymatory. Iodochloride hydrochloride, yellow, m. 111鎺?(decomposition), from ICl.HCl and I in concentrated HCl; it is hydrolyzed by H2O, liberates I from KI and S from aqueous Na2S2O3, 10% NaOH decomposes it quant. into II. Dilute EtOH transforms it into the HCl salt of II, m. 195鎺? II with alk. KMnO4 gives 4-iodopyrazolecarboxylic acid, amorphous, decompose above 70鎺? Ag salt; and 4-iodo-3-(5)-methylpyrazole, m. 185-7鎺? chloroaurate, orange-yellow; chloroplatinate, orangeyellow. With neutral KMnO4 the product is 4-iodo-3-(5)-methylpyrazolecarboxylic acid, amorphous, m. 237鎺?Ag salt. 4-Bromo-3,5-dimethylpyrazole, m. 118鎺?chloroaurate, orange-red, m. 126-8鎺? Ac derivative, m. 38鎺? Bz derivative, m. 48-9鎺? Perbromide, by adding Br to I in concentrated HCl, orange-red, m. 142-4鎺? On warming with EtOH, the HBr salt, m. 174鎺? results. 4-Chloro-3,5-dimethylpyrazole, m. 95鎺? results by passing Cl into aqueous I. It is less basic than the Br or I derivatives and does not yield Ac or Bz derivatives I, warmed with fuming H2SO4 (20% SO3) on the H2O bath for 6 hrs., gives the 4-SO3H acid, containing 1.5 H2O, m. 287-8鎺? the H2O is lost at 115鎺? Chloride, m. 100鎺? In the experiment, the researchers used many compounds, for example, 4-Chloro-3,5-dimethyl-1H-pyrazole (cas: 15953-73-8Name: 4-Chloro-3,5-dimethyl-1H-pyrazole).
4-Chloro-3,5-dimethyl-1H-pyrazole (cas: 15953-73-8) belongs to pyrazole derivatives. Pyrazoles, a five-membered heterocycle containing two adjacent nitrogen atoms, are the core structures found in a number of molecules that possess a wide range of pharmaceutical and agricultural activities. Pyrazole rings have been used as core components of several leading non-steroidal anti-inflammatory drugs (NSAIDs) and antihypertensive drugs. It has also been found to be useful as a bifunctional ligand for metal catalysis.Name: 4-Chloro-3,5-dimethyl-1H-pyrazole
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics