14-hydroxy chlorination

It has been pointed out that there is a torsional-angle (t) dependence of 3-SCS (cf. 40) (104). This angular dependence can be adequately described by multiplying the second term in eq. [15] by cos t (0° t 90°) for the appropriate fragment (104). By that treatment the 3-SCS values of methyl, hydroxy, chlorine, and nitro substituents in bomane (93,104,146,152-154) and twistane derivatives (104,155), which cannot be predicted by the simple eq. [15], become understandable. As expected, such an angular dependence does not exist if t is larger (90° < t < 180°) (156). 

H- l-Benzazepine-2,5-dione, 3-amino-4-methyl-ring contraction, 7, 527 1H-1 -Benzazepine-2,5-dione, 3-hydroxy-chlorination, 7, 517... 

Dibenzofuran, I- and 2-hydroxy-chlorination, 59, 251 chloro-dehydroxylation, 59, 251 Dibenzofuran, methoxy-, dimethoxy-, bromination, 59, 252 Dibenzo[/, /i]quinazoline-2,4-dione, 1,3-dimethyl-, 55, 226... 

To explain the effect of water on the location of chlorine at the surface of the catalyst, a combined time-of-flight-secondary ion mass spectrometry and X-ray photoelectron spectroscopy study has been carried out fresh and used LaMn03+5 catalysts [60]. Both techniques indicated that the presence of chlorine on the tested catalysts increased by exposure of the catalyst to the reactive mixture in dry synthetic air. Chlorine was present as both chloride ion and covalent chlorine on perovskite, while organic chlorinated residues were absent. The lanthanum excess as oxide (hydroxide) partially covering the perovskite mainly transforms into LaOCl and to a minor extent into Lads. Water delays the surface degradation extent of the perovskite into related (oxy) (hydroxy) chlorinated inorganic phases by less molecular chlorine and related chlorine species on the catalyst surface. Equations (17.4)-(17.6) describe the reaction scheme of Cl removal over the investigated perovskite and the role of water. 

The nitrochlorobenzenes are valuable dyestufTs intermediates. The presence of the nitro-groups makes the chlorine atom very reactive and easily replaceable. Treatment with ammonia or dilute alkalis substitutes an amino- or hydroxy-group for the chlorine atom and gives a series of nilroanilines and nilrophenols. 

When unsubstituted, C-5 reacts with electrophilic reagents. Thus phosphorus pentachloride chlorinates the ring (36, 235). A hydroxy group in the 2-position activates the ring towards this reaction. 4-Methylthiazole does not react with bromine in chloroform (201, 236), whereas under the same conditions the 2-hydroxy analog reacts (55. 237-239. 557). Activation of C-5 works also for sulfonation (201. 236), nitration (201. 236. 237), Friede 1-Crafts reactions (201, 236, 237, 240-242), and acylation (243). However, iodination fails (201. 236). and the Gatterman or Reimer-Tieman reactions yield only small amounts of 4-methyl-5-carboxy-A-4-thiazoline-2-one. Recent kinetic investigations show that 2-thiazolones are nitrated via a free base mechanism. A 2-oxo substituent increases the rate of nitration at the 5-position by a factor of 9 log... 

Reactions of the Aromatic Ring. The aromatic ring of hydroxybenzaldehydes participates in several typical aromatic electrophilic reactions. Ha.logena.tlon, Chlorination and bromination yield mono- and dihalo derivatives, depending on reaction conditions. Bromination of / -hydroxy-benzaldehyde in chloroform yields 65—75% of the product shown (39). 

The reactive intermediate, (C2H3)2NCH2CH2C1 HCl, which is used to produce cationic starch, is made by the reaction of (C2H3)2NCH2CH20H with thionyl chloride. A synthetic sweetener (qv), sucralose [56038-13-2] is made by the reaction of sucrose or an acetate thereof with thionyl chloride to replace three hydroxy groups by chlorines (187,188). 

Formation of bound chlorine by reaction of epichl orohydrin with hydroxy groups in the polymer backbones ... 

H-Azepinium perchlorate, 6,7-dihydro-formation, 7, 512 Azepinoindoles synthesis, 7, 537 Azepin-2-one, hexahydro-chlorination, 7, 517 synthesis, 7, 530 Azepin-2-one, 3-hydroxy-methylation, 7, 518... 

H- 3-Benzazepin-2-one, 1 -benzyltetrahydro-chlorination, 7, 518 3H-3-Benzazepin-2-one, 5-hydroxy-synthesis, 7, 528... 

Benzisothiazole, 3-hydroxy-acylation, 6, 159 alkylation, 6, 159 chlorination, 6, 160 organophosphorus compounds, 6, 159... 

Pteridine-6,7-dione, 4-amino-2-chloro-chlorination, 3, 296 Pteridine-6,7-dione, 2,4-dichloro-synthesis, 3, 291 Pteridine-6,7-dione, 5-hydroxy-synthesis, 3, 316 Pteridine-6,7-dione, 8-methyl-reduction, 3, 298 Pteridine-2,6-diones structure, 3, 272 Pteridine-4,6-diones structure, 3, 272 synthesis, 3, 310 Pteridine-6,7-diones reduction, 3, 298 synthesis, 3, 316... 

E rido[2,3-b]pyrazine, 2,3-dihydroxy-chlorination, 3, 251 Pyrido[2,3-b]pyrazine, 6-hydroxy-formation, 3, 251... 

The properties of chlorine azide resemble those of bromine azide. Pon-sold has taken advantage of the stronger carbon-chlorine bond, i.e., the resistance to elimination, in the chloro azide adducts and thus synthesized several steroidal aziridines. 5a-Chloro-6 -azidocholestan-3 -ol (101) can be converted into 5, 6 -iminocholestan-3l -ol (102) in almost quantitative yield with lithium aluminum hydride. It is noteworthy that this aziridine cannot be synthesized by the more general mesyloxyazide route. Addition of chlorine azide to testosterone followed by acetylation gives both a cis- and a trans-2iddMct from which 4/S-chloro-17/S-hydroxy-5a-azidoandrostan-3-one acetate (104) is obtained by fractional crystallization. In this case, sodium borohydride is used for the stereoselective reduction of the 3-ketone... 

Although 16-methylene-17a-hydroxy-20-ketopregnanes can be brominated at C-21 in excellent yield in chloroform containing a small amount of methanol,with A -17a-hydroxy-20-ketopregnanes the use of ethanol alone (containing hydrogen chloride) is far superior. Isolated double bonds (e.g., A, A ) may also be protected prior to bromination by the addition of chlorine. 

Direct bromination readily yields the 6-bromo derivative (111), just as with uracil. Analogous chlorination and iodination requires the presence of alkalies and even then proceeds in low yield. The 6-chloro derivative (113) was also obtained by partial hydrolysis of the postulated 3,5,6-trichloro-l,2,4-triazine (e.g.. Section II,B,6). The 6-bromo derivative (5-bromo-6-azauracil) served as the starting substance for several other derivatives. It was converted to the amino derivative (114) by ammonium acetate which, by means of sodium nitrite in hydrochloric acid, yielded a mixture of 6-chloro and 6-hydroxy derivatives. A modified Schiemann reaction was not suitable for preparing the 6-fluoro derivative. The 6-hydroxy derivative (115) (an isomer of cyanuric acid and the most acidic substance of this group, pKa — 2.95) was more conveniently prepared by alkaline hydrolysis of the 6-amino derivative. Further the bromo derivative was reacted with ethanolamine to prepare the 6-(2-hydroxyethyl) derivative however, this could not be converted to the corresponding 2-chloroethyl derivative. Similarly, the dimethylamino, morpholino, and hydrazino derivatives were prepared from the 6-bromo com-pound. ... 

Chloroquinazoline can be isolated, at best in 40% yield, by boiling 2-hydroxyquinazoline with phosphorus pentachloride in phosphorus oxychloride for 45 min, and attempts to improve this yield have proved fruitless. The yields are much higher when an aryl group is in position 4 w hich suggests an attack of the 3,4-double bond in 2-hydroxy- and 2-chloro-quinazolines by the chlorinating agent. 

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