Replacement of chlorine

Golddll) chloride dissolves in hydrochloric acid to form tetra-chlorauric acid. HAUCI4. Here again, the gold(III) is 4-co-ordinate in the ion [AuCl4] . If alkali is added to this acid, successive replacement of chlorine atoms by hydroxyl groups occurs, forming finally the unstable tetrahydroxoaurate IlI) ion, [Au(OH)4] ... 

Antimony tnfluoride is a mild fluorinating reagent. However, it is much mote effective ia the Swarts reactions where its effectiveness as a fluorinating reagent is dramatically iacteased by addition of CI2, Bt2, or SbCl to the reaction mixture (2). Antimony tnfluotide can be used for the replacement of chlorine or bromine ia halocatbons, hydtohalocatbons, and nonmetal and metal haUdes. Typical reactions can be summarized as follows ... 

The compound is monoclinic at room temperature and has a transition to cubic at 46.9°C. It is prepared by replacement of chlorine in carbon... 

Replacement of Chlorine AEyl choride can be hydrolyzed to aEyl alcohol [107-18-6] under either alkaline or acidic conditions. Other simple replacements of Cl are by I, CN, SCN, NCS, SH, and others. 

In this reaction, three steps, ie, acylation, cyclization, and replacement of the chlorine atom by the hydroxyl group, take place simultaneously in concentrated sulfuric acid. In the course of cyclization 2,7-dichlorofluoran (31) may be formed as a by-product presumably through the carbonium ion (30) ihustrated as follows. The addition of boric acid suppresses this pathway and promotes the regular cyclization to form the anthraquinone stmcture. The stable boric acid ester formed also enables the complete replacement of chlorine atoms by the hydroxyl group. Hydrolysis of the boric acid ester of quinizarin is carried out by heating in dilute sulfuric acid. The purity of quinizarin thus obtained is around 90%. Highly pure product can be obtained by sublimation. 

When an acetylamino group is attached at an ortho position the replacement of chlorine is followed by cyclization. For example, 4-acetylamino-5-chloro-l-phenylpyridazin-6(lH)-one is converted with hydrogen sulfide in DMF to 2-methyl-6-phenylthiazolo[4,5- f]pyridazin-7(6//)-one (116). 

The vapor-phase catalytic replacement of chlorine by fluorine with hydrogen fluoride as the fluorine source has been the subject of a number of patents for the synthesis of Freons or Genetrons This topic has been carefully reviewed in the literature [2, p 97ff] One advantage of using a catalyst with hydrogen fluoride is to allow some degree of selectivity in the displacement of a specific chlorine from... 

With a difluoroethylene containing hydrogen and chlonne, where both groups can be replaced by lithium, a mixture of two organolithium compounds is formed in a 2 1 ratio, indicating a more facile replacement of chlorine [63] (equation 30)... 

In non-polar solvents, the reaction with piperidine is best represented by a two-term kinetic form indicating a mixed 2nd- and 3rd-order reaction. Also, base catalysis by tri-ri-butylamine was observed. This kinetic pattern is strongly reminiscent of the results obtained with nitro-activated benzenes.Another interesting result is that stepwise replacement of chlorine atoms by amino groups results in marked... 

Replacement of chlorine on the pendant benzoyl group by azide is apparently consistent with antiinflammatory activity. Acylation of indomethacin intermediate with p-nitrobenzoyl chloride leads to the corresponding amide (7). Saponification ( ) followed by reduction of the nitro group gives the amine 9. The diazonium salt (10) obtained on treatment with nitrous acid is then reacted with sodium azide there is thus obtained zidomethacin (11). 

C1 Nuclear quadrupole resonance (n.q.r.) studies on PhPCli and PhjPCIa indicated non-equivalence of the chlorine atoms. However, a more recent report states that the spectra of these compounds and PCI5 all contain two signals corresponding to apical and radial chlorine atoms and that replacement of chlorine by phenyl occurs in the radial position. 

Nucleophilic substitution reactions involving the replacement of chlorine (or bromine or fluorine) atoms on the phosphorus have been among the most well studied reactions of cyclophosphazenes... 

Although complete replacement of chlorine atoms can be accomplished with most kinds of amines, this becomes difficult in the reactions with sterically hindered amines. Thus in the reactions of N3P3C16 with cyclohexylamine (71) and adamantyl amine (72), the yields of fully substituted products are low. In the reactions of N3P3C16 with further sterically encumbered amines such as... 

A detailed examination of the kinetics of dimethylaminolysis of N3P3C16 by Krishnamurthy and co-workers has revealed that there is a gradual and subtle mechanistic change that occurs as the degree of replacement of chlorines increases (92). While the first chlorine replacement follows an Sn2 pathway involving the formation of a neutral five-coordinate intermediate [Fig. 8(A)], at the second stage the mechanism can be induced to follow a concerted path [Fig. 8(B)] by using acetonitrile as the solvent. The polar transition state of the concerted path reaction pathway is stabilized in acetonitrile. This postulate has sup-... 

The complete replacement of chlorine in the DDT molecule by fluorine gives (p-FCeH CHCFs, a compound with greatly decreased toxicity toward fruit flies and thrips and probably other species. This reduced activity is matched by the low activity of (p-ClCeH CHCFs which, when contrasted to the potency of DDT and DFDT, shows that the attenuation is caused by the replacement of the three chlorine atoms on the alkane bridge. The corresponding substitution of only one chlorine atom by fluorine gave a compound having as much activity as DDT against the chafer beetle. 

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. 

The diastereomerically pure chlorides 73a and 73b afforded the corresponding P-substitution products on reaction with nucleophiles. Thus 73a and 73b could be converted readily into the corresponding alkoxy-derivatives on treatment with an alcohol in the presence of triethylamine and into aryloxy-derivatives upon treatment with the sodium salt of the appropriate phenol at room temperature. Replacement of chlorine by an alkoxy- or aryloxy-group occurred with retention of configuration, e.g., 73a gave 74a, 75a, and 76a. Similarly, 74b and 75b could be obtained from 73b (Scheme 24) [32, 38, 54],... 

The selective replacement of chlorine in cyanuric chloride by the 3,7-dioxa-r-l-azabicyclo[3,3,0]oct-5-yl-methoxy group through the Williamson method has been described <06T7319>. The reactions of cyanuric chloride with some amine nucleophiles have been described under very mild conditions <06H807>. 

The replacement of chlorine by hydroxyl groups resulting in the formation of hydroxy metabolites, which are excreted or further transformed by conjugation with glucuronic acid... 

A-Acyloxy-A-alkoxyamidcs 20 are synthesised from A-chlorohydroxamic esters 22 by replacement of chlorine by a carboxyl group (Scheme 3). Initially we employed silver acetate in anhydrous ether to make A-acetoxy derivatives.47 However, most have been made using sodium carboxylates in dry acetone by analogy with Finkelstein chemistry.5,38 40>42,43,46,48,49,i05 reacti0ns can be monitored conveniently by thin layer chromatography and A-acyloxy-A-alkoxyamides generally... 

Figure 17. Effect of replacement of chlorine in 2,6-position of the phenyl ring by bromine and trifluoromethyl on blood pressure...

Recently, Johnson and Jonsson (185) as well as Jones and Cram (166) demonstrated that the replacement of chlorine in the optically active sulfonimidoyl chlorides 163 and 167 by phenoxy or dimethyl-amino groups occurs with inversion of configuration. The syntheses of both chlorides and displacement reactions are shown in Schemes 12 and 13 (see page 382). 

Photolytic. Photoproducts reported from the sunlight irradiation of propanil (200 mg/L) in distilled water were 3 -hydroxy-4 -chloropropionanilide, 3 -chloro-4 -hydroxypropionanilide, 3, 4 -di-hydroxypropionanilide, 3 -chloropropionanilide, 4 -chloropropionanilide, propionanilide, 3,4-di-chloroaniline, 3-chloroaniline, propionic acid, propionamide, 3,3, 4,4 -tetrachloroazobenzene, and a dark polymeric humic substance. These products formed by the reductive dechlorination, replacement of chlorine substituents by hydroxyl groups, formation of propionamide, hydrolysis... 

Spirocyclic product is formed as a result of replacement of both the chlorines on the same phosphorus atom, while the ansa product is formed as a result of the replacement of chlorines from two distinct phosphorus atoms within the same molecule. In open chain product only one end of the difunctional reagent is involved in reaction with the chlorocyclophosphazene. Finally, intermolecular bridged products result from the reaction of two chlorocyclophosphazene molecules with a difunctional reagent. This last reaction also is a model reaction for condensation polymerization involving phosphazenes. 

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