Alkyl iodine

Alkyl iodines from alkyl iodines, acetic acid AgY (SiOy/AlyOy = 10) with zirconia or silica binder [243]... 

Weak cationating agents such as alkyl iodine, benzyl halides, and raethyl- toluenesulfonate are able to initiate the polymerization of strong nucleophilic monomers such as cyclic amines (46. 47) and cyclic imino ethers (48-52). 

Gladysz and coworkers reported the synthesis of several fluorous aryl and alkyl iodine(in) dichlorides 14 in 71-98% yields by reactions of chlorine and the corresponding fluorous iodides 13 at room temperature in hexane or chloroform solutions (Scheme 2.5) [74]. A similar chlorination procedure was used to prepare CF3CH2ICI2, CF3CF2CH2ICI2, CF3CF2CF2CH2ICI2 and H(CF2)6CH2lCl2 by Montanari, DesMarteau and coworkers [68,75,76]. 

Likewise, the series of fluorous (dichloroiodo)arenes 127-129 and alkyl iodine(III) dichlorides 130-132 (Figure 5.7) have been prepared in 71-98% yields by reactions of the corresponding fluorous iodides with chlorine [69]. These compounds are effective reagents for the chlorination of alkenes (e.g., cyclooctene) and aromatic compounds (e.g., anisole, 4-rcrt-butylphenol and acetophenone). The organic chlorinated products and fluorous iodide co-products are easily separated by organic/fluorous liquid/liquid biphasic workups. The fluorous iodides can be recovered in 90-97% yields and reoxidized with chlorine [69]. 

Figure 5.7 Recyclable fluorous aryl- and alkyl iodine(lll) dichlorides.

A special apparatus (Fig. Ill, 40,1) renders the preparation of iodides from alcohols a very simple operation. The special features of the apparatus are —(i) a wide bored (3-4 mm.) stopcock A which considerably reduces the danger of crystallisation in the bore of the tap of the iodine from the hot alcoholic solution (ii) a reservoir B for the solid iodine and possessing a capacity sufficiently large to hold all the alkyl iodide produced (iii) a wide tube C which permits the alcohol vapour fix)m the flask D to pass rapidly into the reservoir B, thus ensuring that the iodine is dissolved by alcohol which is almost at the boiling point. An improved apparatus is shown in Fig. Ill, 40, 2, a and b here a... 

The small capacity apparatus is especially recommended for the use of students the consumption of iodine by a large class of students is not unreasonably high. Larger apparatus, e.g., 60 ml. and 100 ml. capacity holding 100 g. and 200 g. respectively of iodine, are generally preferred for routine preparations of alkyl iodides the bolt-head flask should then be of 250 or 500 ml. capacity. Thus for n-butyl iodide a typical preparation would employ 120 g. (148-5 ml.) of n.butyl alcohol, 21 75 g. of red phosphorus, and 200 g. of iodine. 

Cis-olefins or cis./rjns-dienes can be obtained from alkynes in similar reaction sequences. The alkyne is first hydroborated and then treated with alkaline iodine. If the other substituents on boron are alkyl groups, a cis-olefin is formed (G. Zweifel, 1967). If they are cir-alkenyls, a cis, trans-diene results. The reactions are thought to be iodine-assisted migrations of the cis-alkenyl group followed by (rans-deiodoboronation (G. Zweifel, 1968). Trans, trans-dienes are made from haloalkynes and alkynes. These compounds are added one after the other to thexylborane. The alkenyl(l-haloalkenyl)thexylboranes are converted with sodium methoxide into trans, trans-dienes (E. Negishi, 1973). The thexyl group does not migrate. 

Treatment of the borates with iodine leads to boron- C2 migration of an alkyl group[9]. This reaction has not been widely applied synthetically but it might be more applicable for introduction of branched alkyl groups than direct alkylation of an indol-2-yllithium intermediate. 

Chlorination of alkanes is less exothermic than fluonnation and bromination less exothermic than chlorination Iodine is unique among the halogens m that its reaction with alkanes is endothermic and alkyl iodides are never prepared by lodmation of alkanes... 

The order of alkyl halide reactivity in nucleophilic substitutions is the same as their order m eliminations Iodine has the weakest bond to carbon and iodide is the best leaving group Alkyl iodides are several times more reactive than alkyl bromides and from 50 to 100 times more reactive than alkyl chlorides Fluorine has the strongest bond to car bon and fluonde is the poorest leaving group Alkyl fluorides are rarely used as sub states m nucleophilic substitution because they are several thousand times less reactive than alkyl chlorides... 

The reactions of trialkylboranes with bromine and iodine are gready accelerated by bases. The use of sodium methoxide in methanol gives good yields of the corresponding alkyl bromides or iodides. AH three primary alkyl groups are utilized in the bromination reaction and only two in the iodination reaction. Secondary groups are less reactive and the yields are lower. Both Br and I reactions proceed with predominant inversion of configuration thus, for example, tri( X(9-2-norbomyl)borane yields >75% endo product (237,238). In contrast, the dark reaction of bromine with tri( X(9-2-norbomyl)borane yields cleanly X(9-2-norbomyl bromide (239). Consequentiy, the dark bromination complements the base-induced bromination. 

The iodination reaction can also be conducted with iodine monochloride in the presence of sodium acetate (240) or iodine in the presence of water or methanolic sodium acetate (241). Under these mild conditions functionalized alkenes can be transformed into the corresponding iodides. AppHcation of B-alkyl-9-BBN derivatives in the chlorination and dark bromination reactions allows better utilization of alkyl groups (235,242). An indirect stereoselective procedure for the conversion of alkynes into (H)-1-ha1o-1-alkenes is based on the mercuration reaction of boronic acids followed by in situ bromination or iodination of the intermediate mercuric salts (243). 

Various electrophiles other than iodine have been used to induce alkenyl coupling (9). Alkyl haUdes and protic acids react with alkynylborates to yield mixtures of stereoisomeric alkenylboranes. Nevertheless, oxidation of these products is synthetically useful, providing single ketones (296—298). Alcohols are obtained from the corresponding alkenylborates. 

Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CX C) detonates when heated or subjected to shock. It melts at —91.5°C, bods at 80°C, has a molecular weight of 182.914, a heat of vapori2ation of 34.7 kj/mol (8.29 kcal/mol), and, at 0°C, a vapor pressure of 3.2 kPa (23.7 mm Hg) and a density of 1.86 g/mL (14,15). The infrared spectmm is consistent with the stmcture O CIOCIO (16). Cl O decomposes to chlorine and oxygen at low (0.2—10.7 kPa (1.5—80 mm Hg)) pressures and in a temperature range of 100—120°C (17). It is soluble in ben2ene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion. Reaction with olefins yields the impact-sensitive alkyl perchlorates (18). 

Autoxidation of alkanes generally promotes the formation of alkyl hydroperoxides, but d4-tert-huty peroxide has been obtained in >30% yield by the bromine-catalyzed oxidation of isobutane (66). In the presence of iodine, styrene also has been oxidized to the corresponding peroxide (44). 

Dialkyl peroxydicarboaates are used primarily as free-radical iaitiators for viayl monomer po1ymeri2ations (18,208). Dialkyl peroxydicarboaate decompositioas are accelerated by certaia metals, coaceatrated sulfuric acid, and amines (44). Violent decompositions can occur with neat or highly concentrated peroxides. As with most peroxides, they Hberate iodine from acidified iodides. In the presence of copper ions and suitable substrates, dialkyl peroxydicarbonates have been used to synthesi2e alkyl carbonates (44) ... 

The first-order decomposition rates of alkyl peroxycarbamates are strongly influenced by stmcture, eg, electron-donating substituents on nitrogen increase the rate of decomposition, and some substituents increase sensitivity to induced decomposition (20). Alkyl peroxycarbamates have been used to initiate vinyl monomer polymerizations and to cure mbbers (244). They Hberate iodine quantitatively from hydriodic acid solutions. Decomposition products include carbon dioxide, hydrazo and azo compounds, amines, imines, and O-alkyUiydroxylarnines. Many peroxycarbamates are stable at ca 20°C but decompose rapidly and sometimes violently above 80°C (20,44). 

The dipole moment varies according to the solvent it is ca 5.14 x 10 ° Cm (ca 1.55 D) when pure and ca 6.0 x 10 ° Cm (ca 1.8 D) in a nonpolar solvent, such as benzene or cyclohexane (14,15). In solvents to which it can hydrogen bond, the dipole moment may be much higher. The dipole is directed toward the ring from a positive nitrogen atom, whereas the saturated nonaromatic analogue pyrroHdine [123-75-1] has a dipole moment of 5.24 X 10 ° C-m (1.57 D) and is oppositely directed. Pyrrole and its alkyl derivatives are TT-electron rich and form colored charge-transfer complexes with acceptor molecules, eg, iodine and tetracyanoethylene (16). 

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaHy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphoms [7723-14-0] produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-Hthiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has Httie commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). 

Physical Properties. Sulfuryl chloride [7791-25-5] SO2CI2, is a colorless to light yellow Hquid with a pungent odor. Physical and thermodynamic properties are Hsted ia Table 7. Sulfuryl chloride dissolves sulfur dioxide, bromine, iodine, and ferric chloride. Various quaternary alkyl ammonium salts dissolve ia sulfuryl chloride to produce highly conductive solutions. Sulfuryl chloride is miscible with acetic acid and ether but not with hexane (193,194). 

Alkyl and aryl groups are cleaved by iodine, but Cp groups are not affected (285). 

The nitrogen of these aminocarboranes can be alkylated to give, eg, 7-[N(CH3)3]-7-CB2qH22 [31117-16-5]. These compounds give closo-2-(Z. . ]Y, [38102-45-0] upon treatment with Na in tetrahydrofuran (THF) followed by iodine oxidation (eq. 63) (126). 

Hyperthyroidism may be treated in several ways. One of these is interference with the synthesis of the thyroid hormones, possibly by removal of iodine. Thiourea and cyclic thioureas have this effect and of such cyclic compounds, thiouracil (1030 R = H), its 6-alkyl derivatives (1030 R = Me or Pr) and thiobarbital (1031) are effective thyroid drugs. Today only propylthiouracil (1030 R = Pr) is widely used, probably because it has fewer side effects than the others (71MI21302). The thiouracils are made by the Principal Synthesis from a /3-oxo ester (1032 R = H, Me, Pr, etc.) and thiourea (45JA2197) their fine structures are experimentally based (64AF1004). 

The reaction of lithio derivatives with appropriate electrophiles has been utilized in the preparation of alkyl, aryl, acyl and carboxylic acid derivatives. Representative examples of these conversions are given in Scheme 79. Noteworthy is the two-step method of alkylation involving reaction with trialkylborane followed by treatment with iodine (78JOC4684). 

Oxaziridines are powerful oxidizing agents. Free halogen is formed from hydrobromic acid (B-67MI50800). Reduction by iodide in acidic media generally yields a carbonyl compound, an amine and two equivalents of iodine from an oxaziridine (1). With 2-alkyl-, 2-acyl and with N-unsubstituted oxaziridines the reaction proceeds practically quantitatively and has been used in characterization. Owing to fast competing reactions, iodide reduction of 2-aryloxaziridines does not proceed quantitatively but may serve as a hint to their presence. 

Dieckmann reaction, 4, 471 Indolizidine alkaloids mass spectra, 4, 444 Indolizidine immonium salts reactions, 4, 462 Indolizi dines basicity, 4, 461 circular dichroism, 4, 450 dipole moments, 4, 450 IR spectra, 4, 449 reactivity, 4, 461 reviews, 4, 444 stereochemistry, 4, 444 synthesis, 4, 471-476 Indolizine, 1-acetoxy-synthesis, 4, 466 Indolizine, 8-acetoxy-hydrolysis, 4, 452 synthesis, 4, 466 Indolizine, I-acetyl-2-methyI-iodination, 4, 457 Indolizine, 3-acyloxy-cyclazine synthesis from, 4, 460 Indolizine, alkyl-UV spectra, 4, 449 Indolizine, amino-instability, 4, 455 synthesis, 4, 121 tautomerism, 4, 200, 452 Indolizine, 1-amino-tautomerism, 4, 38 Indolizine, 3-amino-synthesis, 4, 461, 470... 

Purine, 9- -D-ribofuranosyl-6-selenoxo- 1,6-dihydro-synthesis, 5, 597 Purine, 6-thiocyanato-acylation, 5, 559 Purine, 2-thioxo-synthesis, 5, 589 Purine, 8-thioxo-iodination, 5, 559 synthesis, 5, 577, 597 Purine, 2-thioxo-2,3-dihydro-synthesis, 5, 572 Purine, 6-thioxo-1,6-dihydro-acylation, 5, 559 dethiation, 5, 558 halogenation, 5, 559 hydrolysis, 5, 560 methylation, 5, 535 oxidation, 5, 560 synthesis, 5, 572, 596 Purine, 8-thioxo-7,8-dihydro-acylation, 5, 559 Purine, 2,6,8-trichloro-alkylation, 5, 530 amination, 5, 562 reactions, 5, 561, 562 with hydriodic acid, 5, 563 with pyridine, 5, 562 synthesis, 5, 598 Purine, 2,6,8-trichloro-7-methyl-synthesis, 5, 557 Purine, 8-trifluoromethyl-synthesis, 5, 574... 

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