Dichloro compound

By side-chain chlorination of the hydrocarbon (Section IV,23), followed by hydrolysis of the dichloro compound, say, with water at 95-100° in the presfflKe of iron as a catalyst, for example ... 

DichlorobenzotrifIuoride. This dichloro compound is produced from 2,4-dichloroben2otrichloride and hydrogen fluoride. One commercial appHcation is the manufacture of the pre-emergent herbicide, dinitramine [29091 -05-2]. 

Direct chlorination of 3,6-dichloropyridazine with phosphorus pentachloride affords 3,4,5,6-tetrachloropyridazine. The halogen is usually introduced next to the activating oxo group. Thus, 1,3-disubstituted pyridazin-6(l//)-ones give the corresponding 5-chloro derivatives, frequently accompanied by 4,5-dichloro compounds as by-products on treatment with chlorine, phosphorus pentachloride or phosphoryl chloride-phosphorus pentachloride. 

Selective substitutions have been most studied in the pyrido[3,4-tf]pyridazine field. The 1,4-dichloro derivative (334) was more reactive than 1,4-dichlorophthalazine, and was expected from MO calculations to show a more reactive 4-chlorine group. In practice, however, almost equal amounts of monosubstitution products were observed on hydrolysis, although slight differences in the use of alkaline and acid conditions, or on hydrazination, have been reported (69CPB2266). Reaction of this 1,4-dichloro compound, or substituted... 

The Phillips Corporation have recently introduced interesting copolymers related to PPS. In addition to the use of p-dichlorobenzene and Na2S, a second aromatic dichloro compound is used. For the marketed material PAS-2 this is 4,4 -dichlorodiphenylsulphone whilst for the developmental products PAS-1 and PAS-B the compounds are 4,4 -dichlorodiphenyl and 4,4 -dichlorodiphenyl-ketone. Each of these copolymers is amorphous, so that a high heat deformation resistance requires a high value for. ... 

B. HI, — 48-4° B. Mel, — 46-6°. A process for the preparation of this substance has been patented in which morphine is warmed at 60° with concentrated hydrochloric acid and the resulting dichloro-compound... 

The limited data available for 2,4-dichloroquinoline (Table X, line 9) show a substantially greater rate of methoxylation than for the 2- and 4-chloro analogs (Table X, line 6 and Table XI, line 2), as a result of activation (lowering of E ) by the additional chlorine substituent. Unequal mutual activation (cf. Section III, B, 2) by these substituents is indicated by the rate ratio of 1.9 1 for 4- to 2-substi-tution in the dichloro compound and of 25 1 for the two mono-chloro compounds. 

Dichloroquinoline with ethanolic potassium hydroxide (80°, 2 hr) gave equal amounts (31 and 32% yields) of 4- and 2-ethoxy-lation. In an earlier paper, only the 2-ethoxy product, in unspecifled yield,was reported. The reaction of the dichloro compound with... 

Finally, the quinoline ring can be methylated at the 3 position with retention of biologic activity. The starting quinoline is prepared by the same scheme as that used for the desmethyl compound by substituting the methylated oxosuccinate ester, S6, in the sequence. The initial quinoline carboxylate (87) is taken on to the dichloro compound (88) by the standard reactions. Condensation with the ubiquitous diamine (76) affords sontoquine (89)... 

A derivative of an isomeric azapurine ring system interestingly exhibits bronchodilator activity, possibly indicating interaction with a target for theophylline. The starting pyridazine 97 is available from dichloro compound 96 by sequential replacement of the halogens. Treatment of 97 with formic acid supplies the missing carbon and cyclizes the intermediate formamide with consequent formation of zindotrine (98) [16]. 

The more halogens on a single carbon, the greater the ease of hydrogenol ysis, a fact that makes stepwise dehydrohalogenation an easy process, since each loss increases the resistance to further loss (4,13,21,24,29,71). Reduction of the dichloro compound 17 over palladium black gave 18 in 98% yield (8). 

Amino-5-methoxy pyrimidine is obtained having a melting point of about 300°C by condensation of methoxymalonic acid ester with guanidine carbonate in the presence of sodium ethylate. The resultant reaction product is then converted to 2-amino-5-methoxy-4,6-di-chloropyrimidine (melting point 216°C to 217°C) by heating this reaction product with phosphorus oxychloride. The dichloro compound is then suspended in water with zinc dust and... 

Figure 17.2 is an example of a mass spectrum of an aromatic dichloro compound. The intensity of the molecular ion indicates that an aromatic compound is present. The isotope pattern is that of two chlorines, and subtracting 70 mass units from the molecular ion gives the formula QHj. (See Example 2.3 in Chapter 2 for another example of isotope abundances in the molecular ion region.)... 

Since nitrobenzene is a much stronger base than alkyl halides, the concentration of RCI.AICI3 will be small and hence k i will be large and, therefore, much greater than k 2. Equation (180), therefore, reduces to a third-order expression which includes the equilibrium constant k jk i) of the first step and this accounts for the lower rates with 4-nitrobenzyl chloride since it is a poorer base than the 3,4-dichloro compound. 

Unfortunately, the method is only suitable for fluorinated systems such as DFDPS. Using chloro monomers generally affords low molecular weight, because a weak base like KF or CsF is needed and DCDPS is not reactive enough under these reaction conditions. However, the activated dichloro compounds can be successfully polymerized in NMP in the presence of equimolar amounts of K2C0371. 

Many of these cobalt complexes will catalyze the reduction of organic compounds by borohydride, hydrazine, thiols, etc. Cobalt cyanide complexes will catalyze the reduction of a,j8-unsaturated acids by borohydride (105) DMG complexes the reduction of butadiene and isoprene by borohydride, but not by H2 (124) Co(II) salen, the reduction of CHCI3 and CH3CCI3 to the dichloro compounds by borohydride (116) and cyanocobalamin, the selective reduction of -CCI2- by borohydride to -CHCl- in compounds such as aldrin, isodrin, dieldrin, and endrin without... 

The silylation-amination of 5,10-dihydroxy-l,4-dioxo-l,2,3,4-tetrahydroben-zo[g]phthalazine 281 for 27 h at 170 °C with excess N(2-aminoethyl)piperidine 282 and HMDS 2 proceeds with catalytic amounts of Ts0H-H20 to afford, via the activated persilylated intermediate in which the sensitive phenolic hydroxy groups are protected, the 1,4-bis-amine 283 in 67% yield. All conventional efforts with POCI3, PCI5, or SOCI2 to convert 281 into the corresponding 1,4-dichloro compound, to be followed by amination, resulted in failure [86] (Scheme 4.35). 

The ynthesis of alkyl(phenyl)trimethylsilylphosphines (59a, b) and the results of an n.m.r. study of their inversion have been reported. The inversion of these compounds has a AG barrier of 19 kcal mol, and a comparison of this value with that of methylphenyl-t-butylphosphine (60), which is known to be about 33 kcal mol at 130 °C, has been made. These data have been discussed in terms of a facilitation of inversion by the react with the dichloro-compounds (61) in which the central atom varies, as shown below. 

In acetic acid, both 1-pentyne and 1-hexyne give the syn addition product. With 2-butyne and 3-hexyne, the major products are p-chlorovinyl acetates of //-configuration.154 Some of the dichloro compounds are also formed, with more of the E- than the Z-isomer being observed. 

The reaction of triphenylphosphine with the geminal dichloro compound (68 R = Cl) in the presence of water leads to the formation of (68 R = H). However, in the absence of water, the... 

In addition to the expected o-aldehyde (68), it is also possible to isolate the unhydrolysed dichloro compound (69). Attack by CC12 at the p-position in (67c) yields the intermediate (70) which, unlike the intermediate for o-attack, has no H atom that can be lost, as H , to allow the ring to re-aromatise (70) thus just acquires a proton, on final acidification, to yield (69). The dichloro compound (69) owes its resistance to hydrolysis partly to its insolubility in the aqueous base medium, but also to the sterically hindered, neopentyl-type environment (cf. p. 86) of the chlorine atoms. 

This polyazide (82.3% N) explodes on impact, shock or rapid heating to 170-180°C [1]. When preparing 2,4-diazido-6-dimethylamino-l,3,5-triazine from the 2,4-dichloro compound and sodium azide, there is the possibility of forming the triazido derivative, which detonates violently when touched. Reactions involving organic chlorides and excess sodium azide are extremely dangerous [2]. 

A mixture of the (highly activated) dichloro compound with potassium fluoride in the solvent was heated to reflux to effect replacement of chlorine by fluorine. The reaction accelerated out of control and exploded, leaving much carbonised residue. Analogous reactions had been effected uneventfully on many previous occasions. See Dimethyl sulfoxide Acyl halides, etc. 

This is probably an intermediate in the preparation of the 1,6-dichloro compound from 2,4-hexadiyne-l,6-diol and thionyl chloride in DMF. The reaction mixture must be kept at a low temperature to avoid vigorous decomposition and charring. This may be due to interaction with the solvent. 

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