3.7- Dichloro-10- -phenothiazine

Brominations mth S Br and PBr. The cyclization of 4,4 -dichlorodiphenylamine (57) with S2Br2 to l,9-dibromo-3,7-dichloro-phenothiazine (59) was already mentioned in Section V,A,l,a. In this reaction cyclization probably takes place before bromination. 

Continuous polymerization in a staged series of reactors is a variation of this process (82). In one example, a mixture of chloroprene, 2,3-dichloro-l,3-butadiene, dodecyl mercaptan, and phenothiazine (15 ppm) is fed to the first of a cascade of 7 reactors together with a water solution containing disproportionated potassium abietate, potassium hydroxide, and formamidine sulfinic acid catalyst. Residence time in each reactor is 25 min at 45°C for a total conversion of 66%. Potassium ion is used in place of sodium to minimize coagulum formation. In other examples, it was judged best to feed catalyst to each reactor in the cascade (83). 

Pechmann reaction, 3, 802 Phenolsulfonephthaleins dyes, 6, 782 Phenosafranine applications, 3, 196 Phenothiazine, 3,7-dichloro-synthesis, 3, 1012 Phenothiazine, 5-ethyl-carbazoles from, 4, 152-153 Phenothiazine, 1-methyl-synthesis, 3, 1033 Phenothiazine, 10-phenyl-synthesis, 3, 1012 Phenothiazine, 10-sulfonyl-rearrangement, 3, 1012 Phenothiazines... 

A-Substituted diphenylamines also yielded phenothiazines on treatment with SOCl2. Thus, A-acetyldiphenylamine (5a) was quantitatively converted into tetrachlorophenothiazine (2a) while A-phenyldiphenylamine (triphenylamine) (5b) gave 3,7-dichloro-lO-(4 -chlorophenyl)phenothiazine (6b) in 91% yield. In the first case... 

As phenothiazine is a good electron donor, there are many papers on the interaction of this compound with various acceptors (see Sections III,A,1, and IV,H,1). In most cases, authentical charge-transfer complexes are obtained however, with very strong acceptors, e.g., 2,3-dichloro-5,6-dicyano-p-benzoquinone, (DDQ), there is total transfer of one electron, leading to It is possible that the same... 

It is now established that the orientation of the reductive halogenation is controlled by nitrogen positions 3 and 7 are occupied first, then 1 and 9. Thus Schmalz and Burger obtained 3-chloro-lO-methyl-phenothiazine (45) from lO-methylphenothiazine-5-oxide (44) and hydrochloric acid, and 3,7-dichloro-lO-methyl-phenothiazine (47)... 

Triphenylsilyllithium converted 2-, 3-, and 4-halogeno-lO-ethyl-phenothiazines into the corresponding triphenylsilyl derivatives, and, in the same way, impure bistriphenylsilyl derivatives have been obtained from 3,7-dichloro- and 3,7-dibromo-lO-ethylphenothiazines. 

H-Phenothiazine l,7-Dichloro-3-oxo- E9a, 525f. (4-C1 —2-SH — anilin + 2,6-Cl2 —1,4-benzoqui-none)... 

Moreover, the operation can also be accelerated by employing a catalyst (cuprous chloride) in solution in an organic solvent (such as a-picoline), and by raising the temperature. Above 160 0, however, large amounts of by-products are formed 1-chloro butadiene, hydrochloric acid and especially polymers. Thus, to prevent these side reactions it is preferable to maintain a low thermal level, 105 to 125°C, and distill under partial vacuum (about 20 kPa absolute), in the presence of an inhibitor intended to prevent polymerizations from developing (phenothiazine). For a once-through conversion of 1,4-dichloro 2-butenes of about 80 per cent, molar selectivity of the 3,4-isomer exceeds 75 per cen t. 

The nature of the products when using zinc thiolates depends on the solvent polarity. For instance, the condensation of zinc salts of substituted 2-amino-benzenethiols 92 with 2,3-dichloro-1,4-naphthoquinones 90 in alcohol, toluene or trichloropropane leads to substituted 6-chloro-5H-benzo[a]phenothiazin-5-ones 93 (88MI1, 93PS(80)23) (Scheme 43). 

Aminobenzenethiols and their salts react with anthraquinones yielding nap-hthophenothiazines. A number of substituted e Jo-12,17-o-phenylene-12,17-dihy-dro-naphtho[2,3-u]-l,4-benzothiazino[3,2 -c]phenothiazines and substituted endo-i, 13-o-phenylene-8,13-dihydro-6-chloro-7H-naphtho[2,3-a]phenothiazin-7-ones have been synthesized (83PS(17)85, 82IJC(B)695) by the condensation of endo-9, 0-o-phenylene-2,3-dichloro-9,l0-dihydro-1,4-anthraquinone with substituted 2-amino-thiophenol and their zinc mercaptides, respectively. 

N-substituted diphenylamines also yielded phenothiazines on treatment with SOCI2 (33GEP562268). In this way, A-acetyldiphenylamine was quantitatively converted into tetrachlorophenothiazine, while A-phenyldiphenylamine (triphenyla-mine) gave 3,7-dichloro-10-(4 -chlorophenyl)-phenothiazine in 91% yield. In the first case, the chlorine atoms in positions 1 and 9 promote the removal of the acyl group from position 10 in the second case, the bulky N-substituent prevents the replacements of hydrogen from positions 1 and 9 by chlorine. The behavior of A-methyl-diphenylamine is intermediate in this respect 3,7-dichloro-lO-methylphenothiazine was isolated in 7% yield, along with tetrachlorophenothiazine (68AHC325). 

Among the most frequently used organic solvents is chloroform, used for the determination of many analytes in various samples free cyanide and thiocyanate ions in human saliva chlorophenols in urine and Bi(III), ethambutol hydrochloride, diclofenac, phenothiazine derivatives, imipramine, warfarin, flufenamic acid, and ethylmorphine in pharmaceutical preparations. Another proposed solvent is dichloro-ethane, used for the determination of bromhexine in serum and imipramine, ambroxol, berberine, bromhexine, neostigmine, 8-chlorotheophylline, and diphenhydramine in pharmaceutical samples. 

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