Prins

Shaofeng Yang, Changhai Liang, Roel Prins  

Institute for Chemical and Bioengineering, ETH Zurich, 8093 Zurich, Switzerland 

Abstract MoP/Si02 and M0P/AI2O3 can be prepared by treating supported Mo metal particles with phosphine and hydrogen. The resulting materials have high activities in the hydrodesulfurization of dibenzothiophene and the hydrodenitrogenation of o-methylaniline. 

To prepare supported MoP catalysts, oxidic precumors were prepared by pore-volume impregnation of y-Al203 (Condea, 90-125 pm, surface area 200 mVg, pore volume 0.9 mPg) and Si02 (chromatography gel C-560, 63-90 pm, surface area 500 m /g, pore volume 1.5 ml/g) with an aqueous solution of 

The HDS of dibenzothiophene (DBT) and the HDN of orthomethylaniline (OMA) were carried out as described elsewhere [12]. A sample of 0.3 g passivated catalyst, which had been phosphided for 2 h at 523 K and heated in H2 for 2 h at 773 or 873 K, was diluted with 8 g SiC to achieve isothermal plug-flow conditions. The catalyst was activated in situ in H2 at 673 K for 3 h. After activation, the pressure was increased to 3.0 MPa and the temperature decreased to 613 K for the hydrotreating reactions. 

---

Spierings G, Koutsos V, Wierenga H A, Prins M W J, Abraham D and Rasing Th 1993 Optical second harmonic generation study of interface magnetism Surf. Sc/. 287-8 747-9... 

Kongingsberger D C and Prins R (ed) 988 X-Ray Absorption Principies, Appiications, Techniques of EXAFS, SEXAFS and XANES (New York Wiley)... 

Leech, J., Prins, J., Hermans, J. SMD Visual steering of molecular dynamics for protein design. IEEE Computational Science Engineering 3(4) (1996) 38-45... 

The Exclusion Prin cip le is t ii an tn ni mechanical in nature, and outside the realm ofeveryday, classical" experience. Think ofii as iheinherent tendency of electron s to slay away from oneanoiher, to be m n tnally excluded. Excbi sion is due to lb c an lisymmdry of the wave function and nol to electrostatic coulomb repulsion between two electrons. Exclusion exists even m the absence of electrostatic repulsions. 

The IlyperChein log file includes calculated dipole moments of 111 oiccu les. To set th e am min t o f in form anon collected in th e log file, eh an gc the value of the Qu an turn Prin t Level set tin g in the eh em. in 1 File. Xote that the sign convention used in the quantum mechanical calculation of dipoles is opposite to that used in 111 oiccu lar mech an ics dipole calculation s this reflects th e differing sign conventions ofphysics and chemistry. 

HypcrCliem provides two form s of param eter sets an. ASCII text form and the Td/ / database form eonsistent with dB.ASH IV and a large n iini her of other database packages. Since the prin cipal diffi-ctilty with using molecular mechan ics is having or obtaining appropriate pa ram eters, you may wan t to explore parameter sets as a database in the Tc// /form. 

Diethyl 3-oxoheptanedioate, for example, is clearly derived from giutaryl and acetic acid synthons (e.g. acetoacetic ester M. Guha, 1973 disconnection 1). Disconnection 2 leads to acrylic and acetoacetic esters as reagents. The dianion of acetoacetic ester could, in prin-ciple,be used as described for acetylacetone (p. 9f.), but the reaction with acrylic ester would inevitably yield by-products from aldol-type side-reactions. 

PdCb-CuCb catalyzes the condensation of branched-chain alkenes with formaldehyde to give the l,3-dioxanes 96a and 96b (Prins reaction)[73]. The yields are much higher than in the conventional acid-catalyzed Prins reaction. 

Prince William Sound Prinivil Prins reaction Print bonding Printed circuit board... 

An important synthetic process for forming a new carbon—carbon bond is the acid-catalyzed condensation of formaldehyde with olefins (Prins reaction) ... 

A commercial process based on the Prins reaction is the synthesis of isoprene from isobutylene and formaldehyde through the intermediacy of 4,4-dimethyl-l,3-dioxane (49—51) ... 

Uses ndReactions. Some of the principal uses for P-pinene are for manufacturing terpene resins and for thermal isomerization (pyrolysis) to myrcene. The resins are made by Lewis acid (usuaUy AlCl ) polymerization of P-pinene, either as a homopolymer or as a copolymer with other terpenes such as limonene. P-Pinene polymerizes much easier than a-pinene and the resins are usehil in pressure-sensitive adhesives, hot-melt adhesives and coatings, and elastomeric sealants. One of the first syntheses of a new fragrance chemical from turpentine sources used formaldehyde with P-pinene in a Prins reaction to produce the alcohol, Nopol (26) (59). 

Uses ndReactions. The Prins reaction of 3-carene with formaldehyde in acetic acid gives mainly 2-carene-4-methanol acetate, which when saponified produces the 2-carene-4-methanol, both of which are commercial products of modest usage (60). 3-Carene (28) also reacts with acetic anhydride with a catalyst (ZnCl2) to give 4-acetyl-2-carene (29) (61), which is also a commercial product. Although 3-carene does not polymerize to produce terpene resins, copolymerization with phenol has been successfully commercialized by DRT in France (62). 

The Prins reaction with formaldehyde, acetic acid, acetic anhydride, and camphene gives the useful alcohol, 8-acetoxymethyl camphene, which has a patchouli-like odor (83). Oxidation of the alcohol to the corresponding aldehyde also gives a useful iatermediate compound, which is used to synthesize the sandalwood compound dihydo- P-santalol. 

Longifolene. There are at least four commercially important aroma chemicals made from (+)-1ongifo1ene and about thirteen products made from (-)-isolongifolene (90) (182). Acetoxymethyl longifolene or the formate are formed during the Prins reaction on (+)-1ongifo1ene. Saponification of the esters gives the useful perfumery alcohol (183) (Fig. 9). 

The Prins reaction on isolongifolene has also produced a number of useful products (185,186). All the products have amber, woody odors, and are known under the names of Amborol, Amboryl Formate, and Amboryl Acetate. 

Condensation of vinyl chloride with formaldehyde and HCl (Prins reaction) yields 3,3-dichloro-l-propanol [83682-72-8] and 2,3-dichloro-l-propanol [616-23-9]. The 1,1-addition of chloroform [67-66-3] as well as the addition of other polyhalogen compounds to vinyl chloride are cataly2ed by transition-metal complexes (58). In the presence of iron pentacarbonyl [13463-40-6] both bromoform [75-25-2] CHBr, and iodoform [75-47-8] CHl, add to vinyl chloride (59,60). Other useful products of vinyl chloride addition reactions include 2,2-di luoro-4-chloro-l,3-dioxolane [162970-83-4] (61), 2-chloro-l-propanol [78-89-7] (62), 2-chloropropionaldehyde [683-50-1] (63), 4-nitrophenyl-p,p-dichloroethyl ketone [31689-13-1] (64), and p,p-dichloroethyl phenyl sulfone [3123-10-2] (65). 

Formaldehyde also reacts with butadiene via the Prins reaction to produce pentenediols or their derivatives. This reaction is cataly2ed by a copper-containing catalyst in a carboxyUc acid solution (57) or RuCl (58). The addition of hydrogen also proceeds via 1,2- and 1,4-addition. 

A. Prins and M. Van den Tempel, Proc. TVth Int. Congr. Suface A.ctive Substances, Bmssels, 2, 1119 (1964). 

PRINS KRIEWITZ Hydrexymslliyiation Acid catalyzed hydroxymethylation of akeras. 1,3-Dk>xafia synthesis. 

C. S. Stewart, M. Fevre and R. A. Prins, in Ruminant Physiology Digestion, Metabolism, Growth and Reproduction, ed. W. von Englehardt, Ferdinand Enke, Stuttgart, 1985, pp. 249-268. 

Proceedings of the 4th International Symposium on Heterogeneous Catalysis and Fine Chemicals, Basel, Switzerland, September 8-12,1996 edited by H.U. Blaser, A. Baikerand R. Prins... 

According to Prins the heptachloropropane can be isolated easily by pouring the reaction mixture into water and removing the unreacted materials by steam distillation. The process is stopped when the product begins to distil, and on cooling the residue is obtained as a colorless solid of the correct melting point. 

The method is essentially that discovered by Boeseken and Prins - and studied further by Prinsd Pentachloroethane can be used in place of tetrachlorethylene, as it is converted into the unsaturated compound in the presence of aluminum chloride. irwiyw.-Heptachloropropane has been obtained also by the action of phosphorus pentachloride on pentachloroacetone, and by treating dichloroacetyl chloride with aluminum chloride. ... 

---