Trichloro production

The striking feature with many of these fluorinations is that the chlorine is displaced to some extent (elemental chlorine has been obtained54 from the products of fluorination) it then enters into the fluorinating agent in some way so that chlorination takes place as well as fluorination, for example, a dichloro starting material can lead to some trichloro products. 

Next, A must be capable of giving 1,2,2-trichloropropane (the product from C). This is not possible for the 1,1-isomer since it already has two chlorines on carbon-1. Therefore, A must be 1,2-dichloropropane it can give the 1,2,2-trichloro product (as well as 1,1,2- and 1,2,3-). By elimination, B is CH3CH2CHCI2. 

The SCF calculations (Section 4.06.2) predict the sequence of electrophilic attack in benzimidazole as 7 > 6 > 5 > 4, although positions 4 and 7, and 5 and 6 are tautomerically equivalent in iV-unsubstituted benzimidazoles. Substitution appears to occur with greatest facility in the 5- (or 6-) positions. Bromination in acetic acid of 2-amino-l-methylben-zimidazole occurs at C-6. It can be seen from Table 5 (Section 4.07.1.4.5) that aqueous bromination of benzimidazole itself occurs most readily at C-5, followed by C-7, as it does in the 1- and 2-methyl analogues (78JCS(P2)865). Some of the experimental results are summarized in Scheme 93. Chlorination of both benzimidazole and 2-methylbenzimidazole give the 4,5,6-trichloro product. Nitration and sulfonation, too, occur most readily at position 5 with either sulfuric or chlorsulfonic acids being effective in the latter reaction. 

In both imidazoles and their /V-substituted derivatives, halogenation occurs preferentially in the 4(5)-positions there is a slight preference for 5-substitution in 1-substituted substrates. Although the 2-position is much less reactive, it is difficult to prevent substitution at that site. Indeed, polyhalogenation is so facile that it is seldom feasible to make monohalogenated imidazoles directly. Both sodium hypochlorite and NCS convert imidazole into its 4,5-dichloro derivative contaminated by the 2,4,5-trichloro product. Even very mild conditions are unlikely to promote monochlorination, and bromination and iodination arc similar. Mechanisms can vary, however, from substrate to substrate. It is likely that C-2 halogenations are the result of addition-elimination [1]. 

CgHjClaOj. M.p. 155°C. Used as a selective herbicide. It is made from 2,4,5-trichloro-pheno) and sodium chloroacetate. Ester sprays and combined ester sprays with 2,4-D are available. 2,4,5-T products are of particular value in that they control many woody species, and eradicate perennial weeds such as nettles in pastures. 

The most common use of 2-(2, 4 -dichlorophenoxy)-5-chlorophenol (2,4,4 -trichloro 2 -phenoxyphenol) is in the personal care products market, where it is commonly known as triclosan and is the active antibacterial in underarm deodorants. It has also found some acceptance as an antibacterial component of plastic mattress covers. 

The kinetics of /V-ch1orination of CA iu basic media have been studied by stopdow spectrophotometry (21). The A/-chloro derivatives are the most important commercial products derived from CA. Their av CI2 and other values appear iu Table 2. Trichloroisocyanuric acid [87-90-17, TCCA, or l,3,5-trichloro-j -tria2iQe-2,4,6(lJT,3JT,5J-i)-trione, is obtained iu - 90% yield by cblorination of aqueous trisodium cyanurate, prepared from CA and NaOH iu a 1 3 molar ratio (22). 

Organic Derivatives. Although numerous mono-, di-, and trisubstituted organic derivatives of cyanuric and isocyanuric acids appear in the hterature, many are not accessible via cyanuric acid. Cyanuric chloride 2,4,6-trichloro-j -triazine [108-77-0], is generally employed as the intermediate to most cyanurates. Trisubstituted isocyanurates can also be produced by trimerization of either aUphatic or aromatic isocyanates with appropriate catalysts (46) (see Isocyanates, organic). Alkylation of CA generally produces trisubstituted isocyanurates even when a deUberate attempt is made to produce mono- or disubstituted derivatives. There are exceptions, as in the production of mono-2-aminoethyl isocyanurate [18503-66-7] in nearly quantitative yield by reaction of CA and azitidine in DMF (47). 

The main product of the alkylation of pentafluorobenzene with 1,1,2-trichloro-tnfluoroethane in the presence of antimony pentafluoride is (i chlorononafluo roethyl benzene [159] (equation 1J6)... 

In a search for fluorocarbons having anesthetic properties, l,2-dichloro-l,l-difluoropropane was subjected to photochemical chlorination. Two isomeric products were obtained, one of which was identified as l,2,3-trichloro-l,l-difluoropropane. What is the structure of the second compound ... 

In a later paper Speziale and Smith 109) investigated the reaction of trivalent phosphorus compounds with N-monosubstituted a-trichloro-acetamides and a-trichloroacetamide. The products were imidoyl chlorides (129) and dichloroacetonitrile (130), respectively. The intermediacy of enamines (131) was assumed. For the monosubstituted amides the enamine... 

Trichloro-l,2,4-triazine was reacted with menthanol and subsequently crystallized from w ater to yield 5-chloro-6-azauracil. A chloro-dimethoxy derivative appears to be an intermediate product, this being further cleaved by hydrogen chloride. No 2,4-dimethoxy derivatives have been prepared so far. 

Trichloro-s-triazine also reacts readily with carbon or phosphorus nucleophiles. Diethylmalonate anion forms a mono-derivative under mild conditions and the tri-substitution product (327) under vigorous conditions with excess nucleophile. Nucleophilic attack by the 7r-electrons of ketene diethylacetal to give 254 and of dimethylaniline to give 253 has been mentioned earlier. Two... 

Reaction of 2,4,7-trichloroquinoline with sodium methoxide (65°, 30 min) yielded an equal mixture of 2,7-dichloro-4-methoxy- (40%) and 4,7-dichloro-2-methoxy-derivatives (31%). The activating effect of the chloro groups is evident from the inertness of 4-chloro-quinoUne to methoxide ion at 65°. Alteration of the relative reactivity by cationization of the azine ring is again noted here in the acid-catalyzed hydrolysis (dilute HCl, 100°, 1.5 hr) of the trichloro compound to give 72% of the 2-hydroxylation product.Similarly, acid-hydrolysis of the alkoxy group proceeds much more readily in 2-ethoxy-4-chloro- than in 4-ethoxy-2-chloro-quinoline. ... 

A mixture of 2.3 parts of 2-(4-methoxyphenyl)ethyl methanesulfonate, 4.9 parts of 1-[(4-fluorophenyOmethyl] -N-(4-piperidinyl)-1H-benzimidazol-2-amine dihydrobromide, 3.2 parts of sodium carbonate, 0.1 part of potassium iodide and 90 parts of N,N-dimethylformamide is stirred overnight at 70°C. The reaction mixture is poured onto water. The product is extracted with methylbenzene. The extract is washed with water,dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloro-methane and methanol (98 2 by volume) as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from 2,2 -oxybispropane, yielding 2.2 parts (48%) of 1 -(4-fluorophenvlmethyl)-N-[1 - [2-(4-methoxvphenyl)ethvl] -4-piperidinyl] -1H-benzlmidazol-2-amine MP 149.1°C. 

Although interesting from a mechanistic point of view, alkane halogenation is a poor synthetic method for preparing alkyl halides because mixtures of products invariably result. For example, chlorination of methane does not stop cleanly at the monochlorinated stage but continues to give a mixture of dichloro, trichloro, and even tetrachloro products. 

A related reaction is the addition of l,l,2-trichloro-2-nitrosoethene to the oxepin/benzene oxide mixture. The primary adduct cannot be isolated but the rearrangement product 9-(tri-chlorovinyl)-tra . -3,6-dioxa-9-azatetracyclo[6.1.0.0z,4.05,7]nonane (6) is obtained in 17% yield.221... 

Addition of cyclopentene to trifluoro-1,2,4-triazine gave products arising from addition of a second molecule of olefin. This was in contrast to trichloro-l,2,4-triazine where the eventual products were predominantly pyridine derivatives [82JCS(P1)1245]. 

Brief reaction of 3-aminodibenzofuran with chlorine in carbon tetrachloride at room temperature gave the 4-chloro product. After 5 min, a 1 0.4 ratio of 3-amino-4-chloro and 3-amino-1,2,4-trichloro derivatives had formed. Subsequent diazotization and reaction with Cu(I)37 Cl gave products with a labeled chlorine in the 3-position (90SC2501). 2-Methoxydibenzofuran was brominated to give the 3-bromo (33%) and a little of the 1-bromo derivative [39JA1365 84AHC(35)2],... 

Chlorination. Electrophilic chlorination of quinoline (66) in neutral medium showed a positional selectivity order of 3 > 6 > 8. The 5- and 8-positions should be sterically hindered to some extent. Hammett cr+ values predict an order for electrophilic substitution of 5 > 8 = 6 > 3. Treatment with chlorine at 160-190°C converted quinoline into a mixture of 3-chloro-, 3,4-dichloro-, 3,4,6- and 3,4,8-trichloro-, 3,4,6,8-tetrachloro-, and 3,4,6,7,8-pentachloro-quinolines. At lower temperatures ( 100°C) the major product was 3-chloroquinoline, albeit in low yield. The 4-substituted species may have arisen from an addition-elimination or radical process (70JHC171). 

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