Alkyl iodide solutions

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... 

Higher alkyl ethers are prepared by treating the sodium derivative of the phaiol (made by adding the phenol to a solution of sodium ethoxide in ethyl alcohol) with the alkyl iodide or bromide (Williamson synthesis), for example ... 

Treatment of an alkaline solution of quinoxalin-2-one or quinoxa-line-2,3-dione with an alkyl iodide or sulfate results in A-methylation. Thus methylation of 3-aminoquinoxalin-2-one (74) with methyl sulfate and alkali gives 3-amino-l-methylquinoxalin-2-one (75) and not as previously reported the isomeric 0-methyl derivative. ... 

Differences in solubility of the reactants may for example be utilized as follows. Sodium iodide is much more soluble in acetone than are sodium chloride or sodium bromide. Upon treatment of an alkyl chloride or bromide with sodium iodide in acetone, the newly formed sodium chloride or bromide precipitates from the solution and is thus removed from equilibrium. Alkyl iodides can be conveniently prepared in good yields by this route. Alkyl bromides are more reactive as the corresponding chlorides. Of high reactivity are a-halogen ketones, a-halogen carboxylic acids and their derivatives, as well as allyl and benzyl halides. 

Haller and Louvrier have prepared a number of homologues of camphor by heating the ketone in benzene solution with sodamide and alkyl iodides. The following are the characters of a number of these —... 

Brown and McDonald (1966) provided another type of kinetic evidence for these size relationships by determining secondary kinetic isotope effects in reactions of pyridine-4-pyridines with alkyl iodides. For example, the isotopic rate ratio in the reaction between 4-(methyl-d3)-pyridine and methyl iodide at 25-0 C in nitrobenzene solution was determined to be kjyfk = l-OOl, while that in the corresponding reaction with 2,6-(dimethyl-d6)-pyridine was 1-095. (Brown and McDonald (1966) estimate an uncertainty of 1% in the k jk values.) Furthermore, the isotopic rate ratio in the case of the 2-(methyl-d3)-compound increased from 1 030 to 1-073 as the alkyl group in the alkyl iodide was changed from methyl to isopropyl, i.e. the isotope effect increased with increasing steric requirements of the alkyl iodide. 

Alkyl esters are efficiently dealkylated to trimethylsilyl esters with high concentrations of iodotrimethylsilane either in chloroform or sulfolane solutions at 25-80° or without solvent at 100-110°.Hydrolysis of the trimethylsilyl esters serves to release the carboxylic acid. Amines may be recovered from O-methyl, O-ethyl, and O-benzyl carbamates after reaction with iodotrimethylsilane in chloroform or sulfolane at 50—60° and subsequent methanolysis. The conversion of dimethyl, diethyl, and ethylene acetals and ketals to the parent aldehydes and ketones under aprotic conditions has been accomplished with this reagent. The reactions of alcohols (or the corresponding trimethylsilyl ethers) and aldehydes with iodotrimethylsilane give alkyl iodides and a-iodosilyl ethers,respectively. lodomethyl methyl ether is obtained from cleavage of dimethoxymethane with iodotrimethylsilane. 

The reaction of alkyl halides with metal nitrites is one of the most important methods for the preparation of nitroalkanes. As a metal nitrite, silver nitrite (Victor-Meyer reaction), potassium nitrite, or sodium nitrite (Kornblum reaction) have been frequently used. The products are usually a mixture of nitroalkanes and alkyl nitrites, which are readily separated by distillation (Eq. 2.47). The synthesis of nitro compounds by this process is well documented in the reviews, and some typical cases are listed in Table 2.3.92a Primary and secondary alkyl iodides and bromides as well as sulfonate esters give the corresponding nitro compounds in 50-70% yields on treatment with NaN02 in DMF or DMSO. Some of them are described precisely in vol 4 of Organic Synthesis. For example, 1,4-dinitrobutane is prepared in 41 -46% yield by the reaction of 1,4-diiodobutane with silver nitrite in diethyl ether.92b 1-Nitrooctane is prepared by the reaction with silver nitrite in 75-80% yield. The reaction of silver nitrite with secondary halides gives yields of nitroalkanes of about 15%, whereas with tertiary halides the yields are 0-5%.92c Ethyl a-nitrobutyrate is prepared by the reaction of ethyl a-bromobutyrate in 68-75% yield with sodium nitrite in DMF.92d Sodium nitrite is considerably more soluble in DMSO than in DMF as a consequence, with DMSO, much more concentrated solutions can be employed and this makes shorter reaction times possible.926... 

Charette et al. converted both primary and secondary alkyl iodides to the corresponding alkylzinc iodides, using either ethylzinc iodide or isopropylzinc iodide.34 The reactions, for example, Scheme 30, which were performed in UV-irradiated (X > 280 nm) chloroform solutions, gave conversions as high as 88% in less than 4h. 

Three-component coupling. Addition of AIBN to a benzene solution of an allylic stannane, an alkyl iodide, and an electron-deficient alkene initiates a radical process that results in 1,2-addition of the alkyl and allyl groups to the alkene.4 Example ... 

As esters the alkyl halides are hydrolysed by alkalis to alcohols and salts of halogen acids. They are converted by nascent hydrogen into hydrocarbons, by ammonia into amines, by alkoxides into ethers, by alkali hydrogen sulphides into mercaptans, by potassium cyanide into nitriles, and by sodium acetate into acetic esters. (Formulate these reactions.) The alkyl halides are practically insoluble in water but are, on the other hand, miscible with organic solvents. As a consequence of the great affinity of iodine for silver, the alkyl iodides are almost instantaneously decomposed by aqueous-alcoholic silver nitrate solution, and so yield silver iodide and alcohol. The important method of Ziesel for the quantitative determination of alkyl groups combined in the form of ethers, depends on this property (cf. p. 80). 

Functionalized organozinc halides are best prepared by direct insertion of zinc dust into alkyl iodides. The insertion reaction is usually performed by addition of a concentrated solution (approx. 3 M) of the alkyl iodide in THF to a suspension of zinc dust activated with a few mol% of 1,2-dibromoethane and MeaSiCl [7]. Primary alkyl iodides react at 40 °C under these conditions, whereas secondary alkyl iodides undergo the zinc insertion process even at room temperature, while allylic bromides and benzylic bromides react under still milder conditions (0 °C to 10 °C). The amount of Wurtz homocoupling products is usually limited, but increases with increased electron density in benzylic or allylic moieties [45]. A range of poly-functional organozinc compounds, such as 69-72, can be prepared under these conditions (Scheme 2.23) [41]. 

O-ALKYLATION PROCEDURE. The extract was O-alkylated according to a method described earlier by Liotta al.(14) using tetrabutylanunonium hydroxide and the appropriate alkyl iodide. The extract (1.00 g) was stirred in freshly distilled tetrahydrofuran (THF) (30 mL) under nitrogen for 30 min. A solution of aqueous tetrabutylanunonium hydroxide (1.53 M, 2.3 ml 3.5 mmol base) was then added and this solution was stirred under nitrogen for 30 min. Alkyl iodide (7.2 mmol) was added and the mixture was stirred under nitrogen at room temperature for 2 days. THF and the alkyl iodide were removed by rotovaporization under reduced pressure. The residue was washed with a hot methanol/water mixture (50/50 vol.) until the filtrate was free of iodide (no precipitate with silver nitrate) and tetrabutylanunonium cation (no precipitate with sodium tetraphenylborate). The all lated extract was then dried under vacuum at 105 "C for 24 hours. 

Oxidation of iodoalkanes involves removal of an electron from the halogen nonbonding orbital. The radical-cations of primary and secondary alkyl iodides can be identified in aqueous solution by their absorption spectra and have half-lives of microseconds [1]. They are formed during pulse radiolysis of the iodoalkane in aqueous solution in the presence of nitrous oxide. This system generates hydroxyl radicals, which remove an electron from the iodine atom lone pair. Iodoalkane radical-anions complex with the lone-pair on other heteroatoms to form a lollo three-electron bond. In aqueous solution, the radical-cation of iodomethane is involved in an equlibrium indicated by Equation 2.1. 

The site and extent of metallation of organolithium compounds can be determined by adding an alkyl iodide, typically Mel, to a solution of the organometallic compound and. 

Alkylation of 5-phenylrhodanines (122) with alkyl iodides and sodium ethoxide yields the meso-ionic 2-alkylthio-l,3-thiazol-4-ones (114, R = SR) 78a structure of the compound 114, R = SMe, R = NHj, R = Ph, was established by X-ray analysis. The dipole moment of the compound 114, R = R = Me, R = Ph, in benzene solution is 5.21 D. Irradiation of the meso-ionic l,3-thiazole-4-thione (114, R = SMe, R = Me, R = Ph) in ethanol yields the isomeric 3-methyl-4-methylthio-5-phenyl-l,3-thiazol-2-one. A novel mechanism for this photochemical rearrangement has been proposed. ... 

In addition to small amounts of methane, acetaldehyde or acetic anhydride can be generated in substantial quantities depending on conditions. However, they are not present simultaneously in any appreciable quantity. Acetic anhydride and acetaldehyde must be competitively formed (equation 6), and subsequently react with each other to form EDA (step C). This reaction (step C) is generally catalyzed by protic acids (2-4). The reaction solution for reductive carbonylation is quite acidic HI is an intermediate generated under reaction conditions of high alkyl iodide concentration and hydrogen pressure. The thermodynamic equilibrium of this condensation is quite favorable for diester formation existence of an abundance of either anhydride or aldehyde in the presence of the other is not found. Yields of stoichiometric preparations are in excess of 95%... 

At this point it is necessary to consider several possible sources of ambiguity in interpretation of the l3 data. First, it should be noted that I2 may form an addition complex (2, 9) with Co(CN)5l 3, just as it does with alkyl iodides in nonaqueous solution. (Experiments bearing on this question are in progress.) Fortunately, the presence of such a complex would not alter the numerical values of the kinetic parameters. Secondly, there is the possibility that Reaction 5 is a trimolecular process, with the I2 and 1 reactants adding to Co(CN)5-2 at separate stages of the reactant. 

Xenon difluoride reacts with alkyl iodides at room temperature to give organic derivatives of polyvalent iodine. When an excess of iodomcthane (7) is treated with xenon difluoride it produces a stable solution of methyliodine difluoride in quantitative yield, the use of hydrogen fluoride as a catalyst allows a substantial amount of product to be obtained, while isopropyl iodide decomposes under the action of the reagent.16-21... 

Alkylation at N( 5) of the cyclic intermediates 38 was accomplished using concentrated solutions of alkyl halides in DMF at 50°C. Addition of a base proved not only unnecessary but even counterproductive in terms of the purity of the resulting Al(5)-substituted benzodiazepi nones 39. Alkyl halides producing good results in this reaction include more than 40 benzyl bromides, allyl bromide, various esters of bromoacetic acid, as well as methyl and ethyl iodide. Other alkyl iodides, along with benzyl chlorides and a-bromo acetophenones, however, did not give satisfactory results. 

Takayama et al. [547] have shown that 3-sulfolene can be directly alkylated at the 2 and 5 positions. The 2-substituted 3-sulfolenes (4) were obtained in a fair yield when the labile sulfolene a-carbanion was generated by LHMDS in a THF-HMPA solution at -78°C in the presence of an alkyl iodide. fran -2,5-Dialkyl-3-sulfolenes (5) were similarly... 

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