Iodine complex alcohol effects

PuUy hydroly2ed poly(vinyl alcohol) and iodine form a complex that exhibits a characteristic blue color similar to that formed by iodine and starch (171—173). The color of the complex can be enhanced by the addition of boric acid to the solution consisting of iodine and potassium iodide. This affords a good calorimetric method for the deterrnination of poly(vinyl alcohol). Color intensity of the complex is effected by molecular weight, degree of... 

The formation of the starch-iodine complex is affected by alcohols. This effect is interpreted as the result of the isolation of polyiodide chains inside the amylose helices as molecules of alcohol also occupy their interior.119198... 

By the reaction of iodine and small amounts of liquid ammonia at -75° a black brown solid is formed. A tensimetric deammonation shows that this solid is an addition compound of iodine and ammonia with 2 moles of ammonia per mole of iodine. Further deammonation effects formation of a compound Ij.NH finally, I remains. Ammonolysis of iodine takes place only to a small extent. These brown addition compounds of iodine correspond to the well known brown addition compounds of iodine and ether, alcohol, pyridine or liquid hydrogen sulfide respectively and are looked upon as charge-transfer complexes with iodine as electron acceptor and the solvents as electron donors. This view was proved by the measurement of the charge transfer band of iodine-ammonia in heptane at 229 m i (2). 

Such reactions are also possible in vitro, as several mild oxidizing agents are at hand nowadays. Thus, the Dess-Martin periodinane (DMP) [50] has been proven to be a versatile and powerful reagent for the mild oxidation of alcohols to the corresponding carbonyl compounds. In this way, a series of new iodine(V)-mediated reactions has been developed which go far beyond simple alcohol oxidation [51], Ni-colaou and coworkers have developed an effective DM P-mediated domino polycy-clization reaction for converting simple aryl amides, urethanes and ureas to complex phenoxazine-containing polycycles. For example, reaction of the o-hydroxy anilide 7-101 with DMP (2 equiv.) in refluxing benzene under exposure to air led to polycycle 7-103 via 7-102 in a yield of 35 % (Scheme 7.28) [52]. 

It is widely employed as a disinfectant in medicine (Povidone-iodine) because of its mildness, low toxicity, and water solubility. According to the U.S. Pharmacopeia, l ovidone-iodme is a free-flowing, brown powder dial contains from 9-12% available iodine. 11 is soluble in water and lower alcohols. When dissolved in water, the uncomplexed free iodine level is very low however, tine complexed iodine acts as a reservoir and by equilibrium replenishes the free iodine lo the equilibrium level. This prevents free iodine from being deactivated because the free form is continually available at effective biocidal levels from this large reservoir. PVP will interact with other small anions and resembles serum albumin and other proteins in this regard. It can be salted in with anions such as NaSC.N or out with NasSOa much like water-soluble proteins. 

ROH - RI,1 Reaction of I2 (1 equiv.) with BH3 QHsNfCjHsJj provides a diiodoborane amine complex in situ that converts alcohols into alkyl iodides in 62-86% yield. It also effects reductive iodination of carbonyl compounds. 

The fact that cinnamyl methyl ether underwent cyclopropanation under similar conditions to afford the corresponding cyclopropane as an almost racemic mixture indicates that the free hydroxy group is necessary for producing an effective chiral environment. This can presumably take place through complexation as a zinc alkoxide. The authors propose that a trinuclear zinc complex 89, in which both the oxygen atom of a zinc alkoxide and iodine atom of iodo-methylzinc contribute to the Lewis character, must be close to the transition structure of the reaction. This might account also for the distinct enantioselectivity between the allylic alcohol and its methyl ether. 

Iodine has different medical uses. The antiseptic tincture of iodine (3% iodine and 2.5% potassium iodide in alcohol) has been known since 1828. PVPI is a modern disinfectant with 1-3% iodine, bound in a complex way to polyvinylpyrroHdone. It is ap-pHed to the skin before surgical operations. Iodine is used as an alternative to chlorine for disinfection of drinking water. Even in such small concentrations as 1 ppm, iodine has a positive effect and is without the negative secondary effects characteristic of chlorine. 

Reaction with Allylic Halides, Alcohols, and their Derivatives. Allylation of allyl and propargyl trimethylsilyl ethers as well as benzyl and propargylic alcohol derivatives proceeds in the presence of a catalytic amount of Lewis acids, such as ZnC, TMS(OTf), and B(C6F5)3. Direct substitutions of the hydroxyl group of allylic, ben-zylic, and propargylic alcohols are catalyzed by HN(S02F)2, a rhenium-oxo complex, and InCls (eq 27). A combination of chlorodimethylsilane and allyltrimethylsilane effectively promotes the deoxygenative allylation of aromatic ketones in the presence of a catalytic amount of an indium compound, such as indium trihalide or metallic indium (eq 28). Allylation of cyclic allylic acetates with allyltrimethylsilane can be catalyzed by molecular iodine. ... 

Quite recently we synthesized polyvinyl alcohol with a small number of camphorsulfonic acid ester groups [19]. The optical activity corresponds to a conversion of about 6%. Although the aqueous solution of this optically active PVA forms a blue complex with iodine-potassium iodide, there is no induced Cotton effect in the visible region (see Section 6). 

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