Sodium-potassium Alloy Research Articles

Effect of randomization on oxidative stability of vegetable oils at two different temperatures

Five vegetable oils were each randomized by chemical means (with the use of a sodium potassium alloy) and by enzymatic means (using a nonspecific lipase). The success of the randomization procedure was confirmed via positional analysis. The oxidative stabilities of the native and chemically randomized oils were determined at storage temperatures of 28°C and 55°C using absorbance at 234 nm as indicative of conjugated diene content. No difference between curves occurred in oils stored at 55°C, however, at the lower temperature all chemically randomized oils had significantly steeper slopes (P<0.05), suggesting a lower stability. When both enzymatically and chemically randomized oils were compared to native oils at 28°C, no significant difference occurred between slopes of native and enzymatically randomized oils, however, the end content of conjugated dienes was significantly higher for chemically randomized canola, corn and soybean oils (P<0.05). No difference was seen between the slopes of the three different oils from either linseed or sunflower. Since both of these oils exhibited higher oxidation rates, it is possible that observation of differences between the stability of native and chemically randomized oild is dependent upon the rate of the reaction.

Solubility of oxygen in sodium-potassium alloys

The solubility of oxygen in liquid sodium-potassium alloy has been measured as a function of temperature and alloy composition. The temperature dependence of the solubility was studied with two different alloy compositions, and the composition dependence at a constant temperature of 473 K. These data are analysed on the basis of various models for the solubility of non-metals in liquid binary alloys.

Polyalkylsilynes: Synthesis and Properties of “Two-Dimensional” Silicon-Silicon Bonded Network Polymers.

ABSTRACTThe synthesis of the first soluble silicon-silicon bonded network polymers, the polyalkylsilynes [RSi]n was accomplished using high-intensity ultrasound to effect the reductive condensation of alkyltrichlorosilanes with liquid sodium-potassium alloy. The resulting polymers remain hydrocarbon-soluble and may be cast into transparent films. Spectroscopic data indicate a structure consisting of tetrahedral alkylsilicon units assembled via silicon-silicon bonds into amorphous networks. Films or solutions of the polysilynes exhibit an intense UV absorption which tails into the visible, blue-shifted but similar in shape and intensity to that of amorphous silicon. The photoreactivity and pyrolysis properties of these materials will be described.

ChemInform Abstract: Tris(3,6‐dioxaheptyl)amine: A Superior Complexing Agent for Dissolving Metal Reactions.

Abstract Commercially available tris(3,6-dioxaheptyl)amine (TDA-1) is an effective phase transfer catalyst for reactions with sodium-potassium alloy in tetrahydrofuran. Deoxygenation of acetates, dehalogenation, and hydrolysis of tosylates and mesylates proceed in high yield. The use of a deuterated alcohol during deoxygenation reactions leads to site-specific deuteration.

Tris(3,6-dioxaheptyl)amine: A superior complexing agent for dissolving metal reactions

Commercially available tris(3,6-dioxaheptyl)amine (TDA-1) is an effective phase transfer catalyst for reactions with sodium-potassium alloy in tetrahydrofuran. Deoxygenation of acetates, dehalogenation, and hydrolysis of tosylates and mesylates proceed in high yield. The use of a deuterated alcohol during deoxygenation reactions leads to site-specific deuteration.

Radical anions of aliphatic diazenes

Radical anions were generated by reduction of aliphatic diazenes with sodium–potassium alloy combined with u.v. irradiation (primary alkyl azo compounds), sodium–potassium alloy (secondary and tertiary alkyl azo compounds) and with crotylpotassium combined with u.v. irradiation (primary, secondary, and tertiaryl alkyl azo compounds); nitrogen hyperfine coupling constants range from 0.775 to 0.883 mT.

ChemInform Abstract: THE CHEMICAL AND ELECTROCHEMICAL REDUCTIONS OF 5‐BROMODECALONE ((4Aα,5α,8Aβ)‐5‐BROMOOCTAHYDRONAPHTHALEN‐1(2H)‐ONE) AND 4‐BROMODECALONE ((4α,4Aβ,8Aα)‐4‐BROMOOCTAHYDRONAPHTHALEN‐1(2H)‐ONE)

AbstractDie Titelverbindung (IV) wird ausgehend von dem I)ion (I) über die Stufen (IIIa) und (IIIb) (Herstellung der Tosylate nach Literaturmethodeybzw.

Dimerisierung von benzocyclobuten zu 1-ethyl-9,10-dihydrophenanthren unter dem einfluss von natrium-kalium-legierung in tetrahydrofuran

Benzocyclobutene is cleaved by sodium-potassium alloy in THF at a C aryl-CH 2 bond whereby in contrast to the corresponding reaction with lithium a dimeric product, 1-ethyl-9,10-dihydrophenanthrene, is formed.

ChemInform Abstract: SOME OBSERVATIONS ON THE CHEMICAL AND ELECTROCHEMICAL REDUCTIONS OF 8‐BROMOBORNAN‐2‐ONE

AbstractDas Brombomanon‐(I) wird von einer Na/K‐Legierung (1:5) in HMPA zu Campher (II) (Ausb.‐ Angabe in mg), in Ether oder Hexan dagegen zu einem Gemisch der isomeren Dihydrocarvone (III) mit dem p‐Menthenol (IV) reduziert.

ChemInform Abstract: REDUCTIVE REMOVAL OF SULFONYL GROUPS: CLEAVAGE OF SULFONAMIDES AND SULFONATES BY ALKALI METAL COMBINED WITH CROWN ETHER

AbstractMit dem System Kalium/Kronenether lassen sich aus Sulfonaten und Sulfamiden die Sulfony‐lreste abspalten.

The preparation and some reactions of tricyclo[4.4.4.0]tetradecane-2,7-dione ([4.4.4]propellane-2,7-dione): X-ray crystal structure of 2,7-bis(trimethylsilyloxy)tetracyclo-[4.4.4.0.0]tetradecane

Tricyclo[4.4.4.0]tetradecane-2,7-dione (1) has been made by reductive alkylation of bicyclo[4.4.0]-dec-1-ene-2,7-dione, using Na–NH3 and Br(CH2)4Br. Reduction of (1) with sodium–potassium alloy in benzene in the presence of chlorotrimethylsilane yields 2,7-bis(trimethylsilyloxy)tetracyclo[4.4.4.0.0]tetradecane (13), whose crystal structure is reported. Reduction of (1) with LiAlH4 and with Na–NH3–ButOH–THF gave mixtures of the three possible diastereoisomeric diols (15)–(17), which could not be separated, but whose isomeric composition could be estimated by 13C n.m.r. spectroscopy. Conformational equilibria in dione (1) and in diol (15) are discussed with the aid of force field calculations.

Some observations on the chemical and electrochemical reductions of 8-Bromobornan-2-one

Reduction of 8-bromobornan-2-one (1) by sodium-potassium alloy in ether, or hexane, gives p-menth-8-en-2-one (3) but in hexamethylphosphoric triamide the product is bornan-2-one (2). Electrochemical reductions at mercury cathodes both in dimethylformamide and hexamethyl-phosphoric triamide give mostly compound (3). Reduction of bromide (1) by tributylstannane is concentration dependent. In concentrated solution compound (2) is the major product but in more dilute solutions compound (3) becomes predominant.

The chemical and electrochemical reductions of 5-bromodecalone [(4aα,5α,8aβ)-5-Bromooctahydronaphthalen-1(2H)-one] and 4-bromodecalone [(4α,4aβ,8aα)-4-bromooctahydronaphthalen- 1(2H)-one

5-Bromodecalone (1) was prepared by the reaction of potassium bromide in acetonitrile on(4aα,5α,8aβ)-5-tosyloxyoctahydronaphthalen-l(2H)-one (15) with apparent retention of configuration. It was also prepared by hydrogen bromide cleavage of (3aRS,3bRS,7aSR)-octahydro-7H-cyclopenta[1,3]cyclopropa[1,2]benzen-7-one (17). On reaction with sodium potassium alloy ketone (1)gives α-decalone (33) and ketone (17) as the principal products whereas reduction with tributylstannane gives only ketone (33). Electrochemical reduction of ketone (1) gives trans-cyclodec-5-en-1-one (3) as well as ketones (17) and (33). 4-Bromodecalone (2) was prepared from(4a,4aα,8aβ)-4-tosyloxyoctahydronaphthalen-1(2H)-one (29), by the reaction with potassium bromidein acetonitrile, with inversion of configuration. Electrochemical reduction of ketone (2) gives trans-1-acetyl-2-vinylcyclohexane (36), α-decalone (33), (E)-cyclodec-4-en-1-one (4) and (laRS,-1bSR,5aRS,6aRS)-octahydrocycloprop[a]inden-6(6aH)-one(24).

Trimethylsilylverbindungen der Vb-Elemente, HI [1]. Tris(trimethylsilyl)- und Tris(trimethylstannyl)bismutan sowie Tetrakis(trimethylsilyl)dibismutan / Trimethylsilyl Derivatives of Vb-Elements, III [1]. Tris(trimethylsilyl)- and Tris(trimethylstannyl)bismuthine as well as Tetrakis(trimethylsilyl)dibismuthine

Abstract Chlorotrimethylsilane and sodium/potassium bismuthide, easily prepared from finely powdered bismuth and sodium potassium alloy in 1,2-dimethoxyethane (DME), react to give tris(trimethylsilyl)bismuthine (1) in 48% yield. When compound 1 is treated with chlorotrimethylstannane all trimethylsilyl substituents are successively replaced by stannyl groups, and tris(trimethylstannyl)bismuthine (4) is obtained. As in analogous reactions of other tris(trimethylsilyl) derivatives of Vb-elements with methyl lithium in diethylether/tetrahydrofuran (THF), one trimethylsilyl group of tris (trimethylsilyl)-bismuthine (1) can also be removed, and lithium bis(trimethylsilyl)bismuthide · 2 THF (5) is formed. With 1,2-dibromoethane bismuthide 6 reacts with metal halogen exchange to give green lustrous needles of tetrakis(trimethylsilyl)dibismuthine (6). In contrast to other dibismuthines described in the literature, this compound is thermally rather stable and can be isolated in preparative amounts. Similar to several distibines a colour change from green to red, resp. orange-red occurs on melting or dissolving dibismuthine 6 in organic solvents.

Reductive removal of sulfonyl groups: Cleavage of sulfonamides and sulfonates by alkali metal combined with crown ether.

A system of potassium metal-crown ether-diglyme has been proved to be highly effective for reductive removal of the sulfonyl group from O-sulfonates or sulfonamides. The reaction proceeds even with mesylamides of dialkyl amines, which resist reductive cleavage by naphthalene radical anion. It has also been found that a simple combination of potassium metal or sodium-potassium alloy with isopropanol in diglyme or toluene is effective for the cleavage of dialkylamine sulfonamides which are relatively susceptible to reduction. In particular, the use of sodium-potassium alloy gave satisfactory results.

Reductive rearrangement of 4-phenyl-1,3-dioxans to 2-phenylbutane-1,4-diols upon treatment with sodium–potassium alloy

Reduction of 4-phenyl-1, 3-dioxan with Na–K alloy affords 2-phenylbutane-1, 4-diol as the major product along with smaller amounts of 3-phenylpropan-1-ol and 3, 4-diphenylhexane-1, 6-diols.

ChemInform Abstract: CONVERSION OF CARBON‐SULFUR LINKAGES INTO CARBON‐SILICON ONES VIA REDUCTIVE SILYLATION. PREPARATION OF SILYL ENOL ETHERS OF ACYLTRIMETHYLSILANES

AbstractDie Silylenolether (II) werden durch Umsetzung der Thiocarbonsäure‐S‐ester (I) mit Li‐diisopropylamid und darauffolgend mit Chlorotrimethylsilan dargestellt.

Conversion of Carbon-Sulfur Linkages into Carbon–Silicon Ones via Reductive Silylation. Preparation of Silyl Enol Ethers of Acyltrimethylsilanes

Abstract Reductive cleavage of carbon–sulfur linkages of silyl enol ethers of thiocarboxylic S-esters can be induced by treatment with sodium or potassium–sodium alloy in the presence of chlorotrimethylsilane, and the corresponding silyl enol ethers of acyltrimethylsilanes can be prepared in high yields.

Dissolving metal reductions with sodium potassium alloy in the presence of 18-crown-6

The dissolving metal reduction of organic compounds can be performed in THF utilizing sodium potassium alloy in the presence of a catalytic amount of 18-crown-6.

N.m.r. spectroscopy of polyesters from bridged bicyclic lactones

The 13C n.m.r. spectra of some polyesters produced by anionic ring-opening polymerization of 2-oxabicyclo[2,2,2] octan-3-one are reported and discussed. From a comparison with the spectrum of the monomer and by hydrolysis of the polymer, it was possible to assign to the polymer, obtained using n-butyllithium as a catalyst, a microstructure in which the ester groups on the 1 and 4 positions of the cyclohexane unit are cis to each other. The polymers obtained both by sodium tert-butoxide and sodium-potassium alloy as initiators, showed spectral differences associated with the presence of another isomeric structural unit. Decreasing of the relaxation times ( T 1) of cis unit by increasing the concentration of this new unit was reasonably explained by assuming for this latter a trans structure linked with the cis unit to form a stereocopolymer.