- Oxidation of terminal diols using an oxoammonium salt: A systematic study
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A systematic study of the oxidation of a range of terminal diols is reported, employing the oxoammonium salt 4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (4-NHAc-TEMPO+ BF4-) as the oxidant. For substrates bearing a hydrocarbon chain of seven carbon atoms or more, the sole product is the dialdehyde. A series of post-oxidation reactions have been performed showing that the product mixture resulting from the oxidation step can be taken on directly to a subsequent transformation. For diols containing four to six carbon atoms, the lactone product is the major product upon oxidation. In the case of 1,2-ethanediol and 1,3-propanediol, when using a 1 : 0.5 stoichiometric ratio of substrate to oxidant, the corresponding monoaldehyde is formed which reacts rapidly with further diol to yield the acetal product. This is of particular synthetic value given both the difficulty of their preparation using other approaches and also their potential application in further reaction chemistry.
- Miller, Shelli A.,Bobbitt, James M.,Leadbeater, Nicholas E.
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supporting information
p. 2817 - 2822
(2017/04/04)
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- PURIFICATION OF 1,3-PROPANEDIOL BY DISTILLATION
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The present invention is a process for purification of 1,3-propanediol (PDO) by an inverted distillation sequence which comprises: (a) optionally removing water or other solvents from the crude 1,3-propanediol mixture; (b) distilling the crude 1,3-propanediol mixture under conditions which maximize the separation of components of the mixture which are heavier than 1,3-propanediol from the 1,3-propanediol and the components which are lighter than 1,3-propanediol; (c) drawing off a stream which contains at least most of the 1,3-propanediol and at least some of the components of the mixture which are lighter than 1,3-propanediol; and (d) distilling the stream of (c) to separate the 1,3-propanediol from components in the stream which are lighter than 1,3-propanediol and any residual components which are heavier than 1,3-propanediol.
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- Method for removal of MW176 cyclic acetal formed during the production of 1,3-propanediol
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The present invention is an improvement upon the process for the production of 1,3-propanediol (PDO) wherein an aqueous solution of 3-hydroxypropanal (HPA) is formed, and the HPA is subjected to hydrogenation to produce a crude PDO mixture comprising PDO, water, MW176 acetal, and high and low volatility materials, wherein the crude PDO mixture is dried to produce a first overhead stream comprising water and some high volatility materials and a dried crude PDO mixture as a first distillate bottoms stream comprising PDO, MW176 acetal, and low volatility materials, and wherein the dried crude PDO mixture is distilled to produce a second overhead stream comprising some high volatility materials, a middle stream comprising PDO and MW176 acetal, and a second distillate bottoms stream comprising PDO and low volatility materials. The improvement on this process comprises treating the crude PDO mixture and/or the dried crude PDO mixture and/or the PDO product with an acidic zeolite, an acid form cation exchange resin, or a soluble acid to convert the MW176 cyclic acetal to more volatile materials which can be easily separated from PDO by distillation.
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- (Dialkoxymethyl)lithiums: Generation, Stability, and Synthetic Transformations
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(Dialkoxymethyl)lithium reagents, (RO)2CHLi, can be generated simply and efficiently and employed as synthetically useful one-carbon nucleophiles.Reductive lithiation of phenylthio-substituted precursors, (RO)2CHSPh, at -95 deg C or transmetalation of tri-n-butylstannyl compounds, (RO)2CHSn(n-Bu)3, at -110 to -111 deg C afforded the acyclic species (MeO)2CHLi (4) and (EtO)2CHLi (5).The cyclic reagents, 2-lithio-1,3-dioxolane (6) and 2-lithio-1,3-dioxane (7), were similarly prepared at -78 deg C by reductive lithiation or transmetalation.Reactions of(dialkoxymethyl)lithiums with electrophiles, including aldehydes, ketones, 2-cyclohexen-1-one (1,2- or 1,4-addition as desired), dimethyl sulfate, primary alkyl bromides, epoxides, oxetane, and n-Bu3SnCl, afforded structurally diverse, functionalized acetals.In these experiments, which emphasized transformations of lithiodioxane 7, yields of products generally exceeded 90percent.The thermal stability of each reagent was investigated at several temperatures.The acyclic compounds 4 and 5 decompose rapidly even at -95 deg C, whereas lithiodioxolane 6 and dioxane derivative 7 are relatively stable at -78 and -45 deg C, respectively.These striking differences in solution lifetimes can be rationalized in terms of alternative decomposition pathways and steric and stereoelectronic factors.The primary products of thermal decomposition of 7 can be ascribed to formation of a reactive carbene or carbenoid via α-elimination.Equilibration experiments established that (dialkoxymethyl)lithium 7 is more stable thermodynamically than the α-monoalkoxy species lithium, in accord with previous ab initio calculations.
- Shiner, Christopher S.,Tsunoda, Tetsuto,Goodman, Burton A.,Ingham, Stephen,Lee, Shi-hung,Vorndam, Paul E.
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p. 1381 - 1392
(2007/10/02)
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- REACTIVITE DES DERIVES DE CYCLOPROPYLIDENE-3 PROPYLE-I. SYNTHESE D'ALCOOLS β-CYCLOPROPYLIDENIQUES
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A series of β-cyclopropylidenic alcohols has been synthesized through the following sequence:(i) Wittig condensation between cyclopropylidenetriphenylphosphorane with appropriate monoprotected 1,3-dicarbonyl compounds; (ii)smooth hydrolysis of acetals (after necessary transacetalization step) and ketals thus formed; (iii) LAH reduction of aldehydes and ketones(yielding primary and secondery alcohols respectively) or treatment of ketones with methyllithium (yielding tertiary alcohols).
- Bertrand, M.,Leandri, G.,Meou, A.
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p. 1703 - 1710
(2007/10/02)
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