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Solvents hydride

Photolysis in MeOD indicates that all three of the above products arise via initial protonation of the double bond to form the 2-phenyl-2-norbomyl cation, which then undergoes either nucleophilic capture by solvent, hydride... [Pg.567]

Lithium aluminum hydride reduction of w-sulfonyloxy groups of furanoid sugar derivatives has been used extensively for the preparation of the corresponding w-deoxy sugar derivatives similar results have been obtained with ether or tetrahydrofuran as the solvent Hydride reduction in ether of 3,5-0-benzylidene-l,2-0-isopropylidene-6-0-p-tolylsulfonyl-a-D-glucofuranose and of 3-0-benzyl-l,2-0-isopropylidene-6-0-p-tolylsulfonyl-o -D-glucofuranose afforded the corresponding 6-deoxy derivative similarly, 1,2-O-isopropylidene-... [Pg.273]

The osmium hydride (CO)ioOs3H2 reacts with isonitriles to give monosubstituted products (CO)io(RNC)Os3H(/2-H), which react further via insertion to give (CO)io(ju-ri -RNCH))(/i-H)Os3. In weak donor solvents, hydride attacks at the carbon whereas strong donor solvents result in hydride attack at nitrogen. The latter reaction results from deprotonation of the hydride complex, followed by reprotonation at nitrogen. [Pg.590]

On treatment of 0-acetylated glycals with triethylsilane and boron trifluoride in inert solvents, hydride enters at C-1 to displace the allylic groups and give 2,3-unsaturated 1,5-anhydroalditols (Scheme 20) [89]. [Pg.169]

If triphenylmethyl chloride in ether is treated with sodium, a yellow colour is produced due to the presence of the anionic spiecies PhsC". Alternatively, if triphenylmethyl chloride is treated with silver perchlorate in a solvent such as THF, the triphenylmethyl cation is obtained. More conveniently, triphenylmethyl salts, PhsC X", can be obtained as orange-red crystalline solids from the action of the appropriate strong acid on triphenylcarbinol in ethanoic or propanoic anhydride solution. The perchlorate, fluoroborate and hexafluoro-phosphate salts are most commonly used for hydride ion abstraction from organic compounds (e.g. cycloheptatriene gives tropylium salts). The salts are rather easily hydrolysed to triphenylcarbinol. [Pg.406]

Since, generally, any base stronger than OH will react with water to produce OH we must use another solvent to observe very strong bases. The high base strengths of the hydride ion and the oxide ion can best be observed in molten salts as solvents, since hydrides and ionic oxides are either insoluble in ordinary solvents or attack them. [Pg.89]

The existence of the hydride ion is shown by electrolysis of the fused salt when hydrogen is evolved at the anode. If calcium hydride is dissolved in another fused salt as solvent, the amount of hydrogen evolved at the anode on electrolysis is 1 g for each Faraday of current (mole of electrons) passed, as required by the laws of electrolysis. [Pg.112]

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). [Pg.10]

Synthesis by high-dilution techniques requires slow admixture of reagents ( 8-24 hrs) or very large volumes of solvents 100 1/mmol). Fast reactions can also be carried out in suitable flow cells (J.L. Dye, 1973). High dilution conditions have been used in the dilactam formation from l,8-diamino-3,6-dioxaoctane and 3,6-dioxaoctanedioyl dichloride in benzene. The amide groups were reduced with lithium aluminum hydride, and a second cyclization with the same dichloride was then carried out. The new bicyclic compound was reduced with diborane. This ligand envelops metal ions completely and is therefore called a cryptand (B. Dietrich, 1969). [Pg.247]

Potassium hydride (1 eq.) was washed with hexanes and suspended in anhydrous ether at 0°C. 7-Bromoindole was added as a solution in ether. After 15 min, the solution was cooled to — 78°C and t-butyllithium (2 eq.) which had been precooled to — 78°C was added by cannula. A white precipitate formed. After 10 min DMF (2 eq.) was added as a solution in ether. The reaction mixture was allowed to warm slowly to room temperature and when reaction was complete (TLC) the suspension was poured into cold 1 M H3PO4. The product was extracted with EtOAc and the extract washed with sat. NaHCOj and dried (MgS04). The product was obtained by evaporation of the solvent and purified by chromatography on silica gel (61% yield). [Pg.141]

Carboxylic acids are exceedingly difficult to reduce Acetic acid for example is often used as a solvent in catalytic hydrogenations because it is inert under the reaction con ditions A very powerful reducing agent is required to convert a carboxylic acid to a pri mary alcohol Lithium aluminum hydride is that reducing agent... [Pg.632]

In contrast to alcohols with their nch chemical reactivity ethers (compounds contain mg a C—O—C unit) undergo relatively few chemical reactions As you saw when we discussed Grignard reagents m Chapter 14 and lithium aluminum hydride reduc tions m Chapter 15 this lack of reactivity of ethers makes them valuable as solvents m a number of synthetically important transformations In the present chapter you will learn of the conditions m which an ether linkage acts as a functional group as well as the methods by which ethers are prepared... [Pg.665]

The carbonyl group of carbohydrates can be reduced to an alcohol function Typi cal procedures include catalytic hydrogenation and sodium borohydnde reduction Lithium aluminum hydride is not suitable because it is not compatible with the solvents (water alcohols) that are required to dissolve carbohydrates The products of carbohydrate reduc tion are called alditols Because these alditols lack a carbonyl group they are of course incapable of forming cyclic hemiacetals and exist exclusively m noncyclic forms... [Pg.1052]

Some elements (S, Se, Te, P, As, Sb, Bi, Ge, Sn, Pb) in liquid samples arc conveniently converted into their volatile hydrides before being passed into the plasma, as discussed in Part A (Chapter 15). For some samples, any volatile solvent is first evaporated in a sample holder, which is then heated strongly to vaporize the resulting solid residue, as discussed in Part C (Chapter 17). [Pg.397]

Hydrazinium salts, N2H5 X, are acids in anhydrous hydrazine, metallic hydrazides, N2H, are bases. Neutralization in this solvent system involves the hydrazinium and hydrazide ions and is the reverse of equation 7. Metal hydrazides, formally analogous to the metal amides, are prepared from anhydrous hydrazine and the metals as well as from metal amides, alkyls, or hydrides. (The term hydrazide is also used for organic compounds where the carboxyUc acid OH is substituted with a N2H2.) Sodium hydrazide [13598-47-5] is made from sodium or, more safely, from sodium amide (14) ... [Pg.275]

Lithium hydride reacts vigorously with siUcates above 180°C. Therefore, glass, quart2, and porcelain containers cannot be used in preparative processes. That only traces dissolve in polar solvents such as ether reflects its significant (60—75%) covalent bond character. It is completely soluble in, and forms eutectic melting compositions with, a number of fused salts. [Pg.297]

Sodium hydride is insoluble in organic solvents but soluble in fused salt mixtures and fused hydroxides such as NaOH. It oxidizes in dry air and hydrolyzes rapidly in moist air. The pure material reacts violently with water ... [Pg.297]

Calcium hydride is highly ionic and is insoluble in all common inert solvents. It can be handled in dry air at low temperatures without difficulty. When heated to about 500°C, it reacts with air to form both calcium oxide and nitride. Calcium hydride reacts vigorously with water in either Hquid or vapor states at room temperature. The reaction with water provides 1.06 Hters of hydrogen per gram CaH2. [Pg.298]

Beryllium Hydride. BeryUium hydride [13597-97-2] is an amorphous, colorless, highly toxic polymeric soHd (H = 18.3%) that is stable to water but hydroly2ed by acid (8). It is insoluble in organic solvents but reacts with tertiary amines at 160°C to form stable adducts, eg, (R3N-BeH2 )2 (9). It is prepared by continuous thermal decomposition of a di-/-butylberylhum-ethyl ether complex in a boiling hydrocarbon (10). [Pg.299]

Magnesium Hydride. Magnesium hydride is a gray powder of about 97% purity which is insoluble in inert organic solvents. It is easily oxidized, and when heated to about 280°C, dissociates without melting when P is in kPa... [Pg.299]

Aluminum hydride, formed from AlCl (44), is a polymeric soHd that is difficult to obtain completely free of the ether solvent used. [Pg.305]

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. [Pg.226]


See other pages where Solvents hydride is mentioned: [Pg.167]    [Pg.168]    [Pg.94]    [Pg.117]    [Pg.167]    [Pg.168]    [Pg.94]    [Pg.117]    [Pg.30]    [Pg.141]    [Pg.425]    [Pg.894]    [Pg.112]    [Pg.879]    [Pg.879]    [Pg.141]    [Pg.142]    [Pg.176]    [Pg.221]    [Pg.121]    [Pg.199]    [Pg.227]    [Pg.308]    [Pg.401]    [Pg.515]    [Pg.64]    [Pg.298]    [Pg.298]    [Pg.311]    [Pg.441]    [Pg.226]   
See also in sourсe #XX -- [ Pg.23 , Pg.269 ]




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