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1.
ACS Omega ; 3(6): 6757-6763, 2018 Jun 30.
Article in English | MEDLINE | ID: mdl-31458848

ABSTRACT

Black liquor (BL) from the kraft pulping process has been treated at elevated temperatures (380 °C) in a batch reactor to give high yields of a bio oil comprising monomeric phenolic compounds that were soluble in organic solvents and mineral oil and a water fraction with inorganic salts. The metal content in the product was <20 ppm after a simple extraction step. A correlation between concentration, temperature, and reaction time with respect to yield of desired product was found. At optimal reaction conditions (treating BL with 16 wt % dry substance at 380 °C for 20 min), the yield of extractable organics was around 80% of the original lignin with less than 7% of char. The product was analyzed by gel permeable chromatography, mass spectroscopy, nuclear magnetic resonance, elemental analysis, and inductively coupled plasma. It was found that a large fraction composed of mainly cresols, xylenols, and mesitols. This process provides a pathway to convert a major waste stream from a pulp mill into a refinery feed for fuel or chemical production, whereas at the same time the inorganic chemicals are recovered and can be returned back to the pulp mill.

3.
ChemSusChem ; 6(3): 426-9, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23303703

ABSTRACT

Transmission of alcohols achieved: A method for the direct transfer of the CHOH function from simple polyols to alkenes has been developed. In a dual-reactor system, successive iridium-catalyzed dehydrogenations and decarbonylations of polyols such as glycerol and sorbitol generates a low pressure of syngas, which is directly used in ex situ alkene hydroformylation.


Subject(s)
Alkenes/chemistry , Carbon Monoxide/chemistry , Glycols/chemistry , Hydrogen/chemistry , Iridium/chemistry , Catalysis , Photochemical Processes , Substrate Specificity
4.
Chemistry ; 18(21): 6507-13, 2012 May 21.
Article in English | MEDLINE | ID: mdl-22532246

ABSTRACT

Several types of chiral hetero- and carbocyclic compounds have been synthesized by using the asymmetric hydrogenation of cyclic alkenes. N,P-Ligated iridium catalysts reduced six-membered cyclic alkenes with various substituents and heterofunctionality in good to excellent enantioselectivity, whereas the reduction of five-membered cyclic alkenes was generally less selective, giving modest enantiomeric excesses. The stereoselectivity of the hydrogenation depended more strongly on the substrate structure for the five- rather than the six-membered cyclic alkenes. The major enantiomer formed in the reduction of six-membered alkenes could be predicted from a selectivity model and isomeric alkenes had complementary enantioselectivity, giving opposite optical isomers upon hydrogenation. The utility of the reaction was demonstrated by using it as a key step in the preparation of chiral 1,3-cis-cyclohexane carboxylates.

5.
J Am Chem Soc ; 132(26): 8880-1, 2010 Jul 07.
Article in English | MEDLINE | ID: mdl-20557052

ABSTRACT

A range of saturated chiral azacycles has been prepared in high yield and with high selectivity from simple starting materials. A modular approach with ring-closing metathesis as a key step was used to produce a number of five-, six-, and seven-membered cyclic alkenes. Asymmetric hydrogenation catalyzed by N,P-ligated iridium complexes gave saturated azacycles in high optical purity. This methodology was demonstrated in the synthesis of a pharmaceutical precursor.


Subject(s)
Aza Compounds/chemistry , Aza Compounds/chemical synthesis , Iridium/chemistry , Alkenes/chemistry , Catalysis , Hydrogenation , Pyridines/chemistry , Stereoisomerism , Substrate Specificity , Tosyl Compounds/chemistry
6.
J Am Chem Soc ; 131(34): 12344-53, 2009 Sep 02.
Article in English | MEDLINE | ID: mdl-19658416

ABSTRACT

A modular library of readily available phosphite-oxazoline ligands (L1-L16a-f) has been successfully applied for the first time in the Ir-catalyzed asymmetric hydrogenation of a broad range of highly unfunctionalized 1,1,-disubstituted terminal alkenes. Enantioselectivities up to >99% and full conversions were obtained in several 1,1-disubstituted alkenes, including substrate classes that have never been asymmetrically hydrogenated before (i.e., 1,1-heteoraryl-alkyl, 1,1-diaryl, trifluoromethyl, etc.). The results indicated that these catalytic systems have high tolerance to the steric and electronic requirements of the substrate and also to the presence of a neighboring polar group. The asymmetric hydrogenations were also performed using propylene carbonate as solvent, which allowed the Ir catalyst to be reused and maintained the excellent enantioselectivities.


Subject(s)
Alkenes/chemistry , Iridium/chemistry , Organometallic Compounds/chemistry , Oxazoles/chemistry , Phosphites/chemistry , Catalysis , Hydrogenation , Models, Molecular , Molecular Conformation , Stereoisomerism , Substrate Specificity
7.
Chem Commun (Camb) ; (33): 3888-90, 2008 Sep 07.
Article in English | MEDLINE | ID: mdl-18726024

ABSTRACT

High enantioselectivities and activities are achieved in the Ir-catalyzed hydrogenation of several unfunctionalized olefins using modular biaryl phosphite-oxazoline ligands from hydroxyl aminoacid derivatives; the presence of a biaryl phosphite group is crucial to this success.


Subject(s)
Alkenes/chemistry , Iridium/chemistry , Oxazoles/chemistry , Catalysis , Ligands
8.
J Am Chem Soc ; 130(23): 7208-9, 2008 Jun 11.
Article in English | MEDLINE | ID: mdl-18481850

ABSTRACT

We have described the first successful application of a phosphite-oxazoline ligand library in the asymmetric Ir-catalyzed hydrogenation of several unfunctionalized olefins. The introduction of a bulky biaryl phosphite moiety in the ligand design is highly adventitious in the product outcome. By carefully selecting the ligand components, we obtained high activities (TOFs up to >1500 mol x (mol x h)(-1) at 1 bar of H2) and enantioselectivities (ee values up to >99%) and, at the same time, show a broad scope for different substrate types. So, this is an exceptional ligand class that competes favorably with a few other ligand series that also provide high ee values for tri- and disubstituted substrate types.


Subject(s)
Alkanes/chemical synthesis , Alkenes/chemistry , Oxazoles/chemistry , Phosphites/chemistry , Pyrans/chemistry , Catalysis , Hydrogenation , Iridium/chemistry , Ligands , Oxazoles/chemical synthesis , Phosphites/chemical synthesis , Pyrans/chemical synthesis , Stereoisomerism
9.
Dalton Trans ; (47): 5603-10, 2007 Dec 21.
Article in English | MEDLINE | ID: mdl-18043823

ABSTRACT

New diastereomeric N,P-ligands, derived from the natural product (+)-alpha-pinene, have been synthesized and evaluated in iridium-catalyzed asymmetric hydrogenation. The ligands are tetrahydroquinoline derivatives synthesized directly from commercially available alpha-pinene utilizing resolution or recrystallization to separate diastereomers. In reduction of a range of different trisubstituted alkenes the catalysts express very different activities ranging from no activity to high activity. One of the catalysts gives good ee values for some substrates.


Subject(s)
Hydrogen/chemistry , Monoterpenes/chemistry , Bicyclic Monoterpenes , Catalysis , Ligands , Magnetic Resonance Spectroscopy , Spectrometry, Mass, Electrospray Ionization , Spectrophotometry, Infrared
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