Homologues, preparation

Fig. 3. (A) Sequence alignment of five MscL homologues prepared by the program...

Fittig s Reaction.—The most important reaction of the benzene halogen substitution products is what is known as Fittig s reaction, by means of which a paraffin chain may be substituted in the benzene ring, and benzene homologues prepared. 

COFj POLYMERS AND HOMOLOGUES PREPARED BY OXIDATION OF CjFg [1872]... 

These findings confirm the model of polydisperse systems of homogeneous spheres by exact fits of the static light scattering curves, the expected M a3 dependence for PEC homologues prepared at different polymer concentrations, and the asymptotic q 4 behavior of compact spheres. The quantitative information obtained shows that the concentration of the component solutions does not affect the internal structure of the PECs remarkably but controls their level of aggregation to a great extent. 

The necessity to replace materials based on dwindling fossil resources by homologues prepared from renewable counterparts has become an urgent matter for environmental and economical reasons. Within this context, starch... 

The acidity and strength distribution of acid sites of a ZSM-5 prepared by hydrothermal synthesis, and zinc and gallium incorporated ZSM-5 catalysts prepared by incipient wet impregnation were compared to those of homologues prepared by a co-synthesis method. Ammonia adsorption microcalorimetry showed that samples prepared by co-synthesis exhibited lower acidity values when compared to the others [191]. 

It has been mentioned ( 4.4.2) that nitronium tetraffuoroborate reaets with pyridine to give i-nitropyridinium tetraffuoroborate. This compound and several of its derivatives have been used to effect what is called the transfer nitration ofbenzeneandtoluene. i-Nitropyridinium tetraffuoroborate is only sparingly soluble in acetonitrile, but its homologues are quite soluble and ean be used without isolation from the solution in which they are prepared. i-Nitropyridinium tetra-fluoroborate did nitrate toluene in boiling aeetonitrile slowly, but not at 25 In eontrast, i-nitro-2-pieolinium tetraffuoroborate readily... 

Homologues in principle can also be prepared from RCH(Br)-C(8r)=CH2 but for the synthesis of these starting compounds three steps have to be carried out. The dehalogenation procedure has also been used in the preparation of di- and tri-fluoroal1enes. ... 

Tosylates of pentaerythritol and the higher homologues can be converted to their corresponding tetra-, hexa-, or octaazides by direct reaction of sodium azide (36), and azidobenzoates of trimethyl olpropane and dipentaerythritol are prepared by reaction of azidobenzoyl chloride and the alcohols in pyridine medium (37). 

Petfluotoalkanesulfonic acids also show high acidity. The parent trifluoromethanesulfonic acid (triflic acid), CF SO H, is commercially prepared by electrochemical fluorination of methanesulfonic acid (214). It has an value of —14.1 (215,216). The higher homologues show slightly decreasing acidities. 

Diacetylphloroglucinol and its homologues have been prepared and found to be inhibitors of the herpes vims (188). Syzygiol (50), a skin tumor promotion inhibitor, has been prepared from phloroglucinol (189). The first natural morphogen (cell-differentiation agent) (51) has also been identified as a phloroglucinol derivative (190). 

Trichloromethanesulfenyl chloride has also been used for the preparation of lubricant additives (see Lubrication and lubricants). Some higher homologues and analogues of trichloromethanesulfenyl chloride have been reported, ie, trichlorovinylsulfenyl chloride [19411-15-5] 1,1,2,2-tetrachloroethanesulfenyl chloride [1185-09-7] 1,2,2,2-tetrachloroethanesulfenyl chloride [920-62-7] and pentachloroethanesulfenyl chloride [5940-94-3] (70—74). A commercial fungicide, Captafol [2425-06-17, is the reaction product of 1,1,2,2-tetrachloroethanesulfenyl chloride with tetrahydrophthalimide (75). 

Molecular modifications of the morphine skeleton have produced numerous derivatives with antitussive properties, some of which have become commercially significant. Ethyknorphine [76-58-4] (29), a simple homologue of codeine, is prepared by ethylating morphine. It is pharmacologically similar to codeine but is seldom used clinically. Pholcodine [509-67-1] (30), the morpholinoethyl derivative of morphine, is used as an antitussive in a number of European countries. It is about one and a half times as potent as codeine, has Htde or no analgesic activity, and produces minimal physical dependence. The compound is prepared by the amino alkylation of morphine (48). 

The present method is applicable with slight modifications to the preparation of both the ortho and para aminonaphthols and to many homologues, benzologues, and heterocyclic isologues of these substances. The chief feature of novelty is in the use of stannous chloride as an antioxidant in preparing and crystallizing the amine hydrochlorides. 

When just a trace of dark impurity is present, as in some of the commercial preparations, a completely pure product is easily obtained by vacuum distillation, but the ordinary crude reaction product is likely to decompose when treated in this manner. The ether method introduced in the present procedure has the advantage of being simple and efficient. It is equally applicable to the purification of the homologues of a-naphthoquinone. 

A number of homologues of codeine have been prepared by the alkylation of morphine for example, ethylmorphine, which is used in medicine... 

Quaternary salts of the substances represented by tliese formulae have been prepared by Kogl, Veldstra and van der Laan as well as of the next lower homologues, the substituted butyraldehydes, and the methyl ethers of both series. Their pharmacological activities were negligible in comparison with that of muscarine, but as six stereoisomeric forms may be produced in each synthesis, the inactivity may be due to stereoisomerism, just as in the case of threonine (a-amino-)3-hydroxy-butyric acid) where West and Carter found that only the d —) form is... 

Whereas access to fluoromethylene ylides is easy, higher homologues are more difficult to prepare because ot the facile (1-elimination of fluorine However hexafluoroisoprapylidene ylides may be prepared in situ from tetrakisftnfluoro-methyl)-l,3-dithietane and tnphenylphosphme [54 (equation 51) or 2,2-dichloro-hexafluoropropane and tnphenylphosphme [55, 56, 57 (equation 52) (Table 21) Pcrfluoro-2-buteiie reacts with tnbutylphosphine to cleanly form a solution of a fluonnated ylide [5/ ] (equation 53)... 

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