8-Vinyl chlorins

Aspartic Acid Derivative of Chlorineb (Npe6) Alkyl Ether Derivatives of Pyropheophorbide a Alkyl Ether Analogs of Purpurinimides Benzoporphyrin Derivatives from Pyropheophorbide A and Purpurinimides vic-Dihydroxy-and Ketobacteriochlorins Bacteriochlorins Derived from 8-Vinyl Chlorins Bacteriochlorins from Bacteriochlorophyll... 

As with both terminal and cyclic olefins containing vinylic chlorine or bromine, acyclic counterparts partly lose the halogen first and then undergo dihydrogenation to the tetrahydro dcnvative [54] (equation 44) When the reachon IS earned out in the hquid phase in the presence of base, yields of tetrahydro product are enhanced [55] (equation 44)... 

Flame resistance The underwriters ruling on the use of self-extinguishing plastics for contact-carrying members and many other components introduces critical material selection problems. All TSs are basically self-extinguishing. Nylon, polyphenylene oxide, polysulfone, polycarbonate, vinyl, chlorinated polyether, chlorotrifluoroethy-lene, vinylidene fluoride, and fluorocarbon are examples of TPs that may be suitable for applications requiring self-extinguishing properties. Cellulose acetate and ABS are also available with these properties. Glass reinforcement improves these materials considerably. 

Continuing this trend, vinylic bromine can be much more easily hydrogenolyzed than vinylic chlorine over a palladium catalyst.437... 

Scheme 160 Cathodic removal of a vinylic chlorine atom.

This stereochemical outcome of the Fritsch-Buttenberg-Wiechell rearrangement is well compatible with the crystal structure of the carbenoid 3 (Figure 1, Scheme 4). The aryl moiety trans to the vinylic chlorine atom is bent towards Cl (C1-C2-C9 116.5°). Thus, migration of the fraw -aryl group with simultaneous liberation of lithium chloride becomes evident. The free vinylidene carbene can be ruled out as the intermediate. 

The fluorination of polyfluorocyclohexenes with antimony(V) fluoride proceeds under much more severe temperature conditions ( 150 C) than with vanadium(V) fluoride (see Section 12.4.2). In these reactions antimony(V) fluoride effects both the oxidative addition of fluorine and the substitution of vinyl chlorine atoms by fluorine.48... 

The presence of a strong activating a-group always controls the substitution course, e.g. compound (21) loses only the chlorine /J to the carbonyl group (McBee et al., 1962b) while (22) loses the vinylic chlorine atom rather than fluorine (Scherer et al., 1966). 

Pyrethroid insecticides. Continued interest in and research into this important class of insecticides has resulted in a number of important discoveries, one of which involved replacement of the vinylic chlorine of traditional pyrethroids with trifluoromethyl to give X-cyhalothrin (Cyhalon , Grenade ) (ICI/Zeneca) [171], in... 

If one further regards the highly effective and rapidly acting lindane as a better fit to the same target that is affected by dieldrin, then the two vinylic chlorines and the syn-Cl of the... 

In the molecule SBD, the reduction in toxicity effected by replacement of the syn-chlorine of dieldrin to give SD appears to be offset by an increase (compare BD) effected by further replacement of the vinylic chlorines, so that SBD is similar to dieldrin in toxicity In contrast, AD and ABD, which retain the syn chlorine, are poor toxicants In this series there was no appreciable synergism with the MFO inhibitor sesamex, indicating that when increased LD50s were seen, these were not the result of enhanced MFO attack consequent upon the progressive replacement of chlorine ... 

This yet incomplete study shows that in all series for which information is available, the bridge anti-Cl(A) is indeed more important than the syn-C1 (s) for toxicity, but replacement of the vinylic chlorines does not necessarily confer the toxicity increase found in the dieldrin series ... 

The clue to the reaction is the polarity of the double bond. The lowest electron density is at the carbon linked to hydrogen, and is due to the strong inductive effect of the difluoromethylene groups and a slight effect of the vinylic chlorine. The attacking species, ethoxide anion, which is in an equilibrium with hydroxide ion in alcoholic potassium hydroxide, reacts in an SN2 reaction by joining the carbon bonded to hydrogen. The subsequent shift of the double bond facilitates ejection of fluorine as an anion and leads to an ether, compound O [77]. 

The bridgehead chlorines in 1,2,3,4-tetrachloronorbornene (90) are not removed, although they are allylic in the hydrogenation over Raney Ni in methanol in the presence of potassium hydroxide, only the vinylic chlorines are lost to give 1,4-dichloronorbornane (eq. 13.124).224... 

Similarly, 1,2,3,4,7,7-hexachloronorbornene (91, X = Cl) and l,2,3,4-tetrachloro-7,7-dimethoxynorbornene (91, X = OMe) are hydrogenated without losing the allylic chlorines in the hydrogenation over Pd-C in ethanol in the presence of triethylamine only the vinylic chlorines are removed (eq. 13.125).225 The 7,7 bridge chlorines of the product may be further reduced to 1,4-dichloronorbornane by diphenyltin dihydride in diglyme at 110-120°C. 

Reaction of perfluoro-1,2-dichlorocycloaik-l-enes 16 with sulfur-containing nucleophiles or copper thioiates leads to substitution of the vinylic chlorine atoms. 

The usually greater reactivity of vinylic fluorine than vinylic chlorine is demonstrated in methanolyses of halonitrostyrenes [44] (Table 5.6), providing support for the two-step process with a rate-limiting addition stage outlined above. 

The stoichiometric reaction of CFC-113 with metallic zinc to produce chlorotrifluoroethylene is a well-known process. Catalytic approaches to this synthesis are also available. Charcoal (47) as well as supported nickel, iron, cobalt, and chromium operating at elevated temperature (48) give chlorotrifluoroethylene yields in excess of 90%. The selective replacement of the vinylic chlorine by hydrogen while still maintaining the olefinic linkage provides still another entry into trifluoroethylene. 

Selective replacement of the vinylic chlorines t es place in the hydrogenation of chlorinated norbor-nenes (equations 7 and 8), which suffer saturation of the double bonds as well as hydrogenolysis of the chlorines. ... 

Vinylic chlorine is replaced by hydrogen in l-chloro-3,4-dihydro-2-naphthaldehyde during catalytic hydrogenation, which saturates the double bond, but leaves the aldehyde group intact (equation 9). ... 

Replacement by hydrogen of vinylic chlorine without reduction of the double bond can be accomplished by complex hydrides. The effrcacy of lithium aluminum hydride is increased by titanium tetra-... 

Reduction with metals such as sodium, lithium and zinc leaves the double bonds intact, with rare exceptions. In (5), both allylic and vinylic chlorine atoms are replaced by hydrogen using sodium or lithium in r-butyl alcohol. While sodium does not reduce the double bond, lithium affords a mixture of (6) and (7) (equation 12). ... 

Zinc in acetic acid hydrogenolyzes vinylic chlorine in phenyl (Z)-p-chlorostyryl sulfone (equation 14). ... 

Vinylic bromine can be replaced fairly easily without reduction of the double bond. This is a characteristic difference from hydrogenolysis of vinylic chlorine and especially fluorine. Catalytic hydrogenation of ethyl a-methyl-3-bromocrotonate resulted in replacement of bromine and formation of ethyl a-methylcrotonate (equation 15). In 14-bromocodeinone (9), replacement of bromine occurs with a double bond shift to give neopinone (10 equation 16).4... 

In another version of this reaction, fluorine atoms were replaced by chlorine atoms. Thus, the 1,3-dithiole 542 was prepared in the reaction of the pentachlorobutadiene 541 with benzene-1,2-dithiol 538 according to the general scheme, previously referred to in CHEC-11(1996), involving an exchange of the vinyl chlorine atom by the thiolate sulfur (Equation 67) <1997PS79, 2002PS2529>. 

Synonyms Chlorethene Chlorethylene Chlor-oethene Chloroethylene Ethene, chloro- Ethylene monochloride Ethylene, chloro- Monochlor-oethene Monochloroethylene Monovinyl chloride Trovidur VC VCM Vinyl C monomer Vinyl chloride monomer Vinyl chlorine Related Compounds Vinyl bromide (CAS 593-60-2) Vinyl fluoride (CAS 72-02-5) Vinylidene chloride (CAS 75-35-4) 1,2-Dichloroethene (CAS 540-59-0) Elexachlorobutadiene (CAS 87-68-3)... 

On the other hand, sterically crowded allylamine 21 was cyclopropanated giving 22 in spite of the two vinylic chlorine atoms which deactivate the double bond to the attack of dichlorocarbene (see also Houben-Weyl, Vol. E19b, pl555). 

The meta photocycloaddition of ( )-l,2-dichloroethene with benzonitrile, toluonitriles, benzene, phenol, cresols, fluorobenzene, chlorobenzene, trifluoromethylbenzene and 3-trifluoro-methylbenzonitrile shows not only the influence of the aromatic substituents on the direction of the alkene attack, but also a control of the cyclopropane closure by the vinyl chlorine to give exclusively the exo-(>, ent/o-7-dichloro adduct isomer 5 which was, in the most favorable cases, isolated in gram quantities. ... 

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