1- Pentenoic acid

Obviously, the use of a nonvolatile ionic liquid simplifies the distillative workup of volatile products, especially in comparison with the use of low-boiling solvents, where it may save the distillation of the solvent during product isolation. Moreover, common problems related to the formation of azeotropic mixtures of the volatile solvents and the product/by-products formed are avoided by use of a nonvolatile ionic liquid. In the Rh-catalyzed hydroformylation of 3-pentenoic acid methyl ester it was even found that the addition of ionic liquid was able to stabilize the homogeneous catalyst during the thermal stress of product distillation (Figure 5.2-1) [21]. This option may be especially attractive technically, due to the fact that the stabilizing effects could already be observed even with quite small amounts of added ionic liquid. 

Acetoxy-1,4- naphthoquinone [ 1,4-Naphthalenedione, 2-(aoetyloxy)-] 4-Methyl-3-pentenoic [3-Pentenoic acid, 4-methyl-] 2-Acetoxy-3-(y,y-dimethylallyl) [1,4 -Naphthalen ed i one, 2-(acetyloxy)-3-(3-methyl-2-butenyl)-] 73 4... 

Pentenoic acid 4-methyl-, 70 3 Penten 2-ol, 3 bromo, acetate, 35 3-Penten-2-ol, 3-bromo-4-methyl-, acetate,... 

DIMETHYLKETENE /3-LACTONE DIMER (3-Pentenoic acid, 3-hydroxy-2,2,4-trimethyl- /3-lactone)... 

Caution The starting material in this preparation, 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid (i-ladone, is a mild hut deceptively persistent lachrymator. 

A mixture of 5 g. of anhydrous zinc chloride (Note 1) and 280 g. (2.00 moles) of 3-hydroxy-2,2,4-trimethyl-3-pentenoic acid /9-lac-tone 2 is placed in a 500-ml. three-necked flask equipped with a sealed stirrer (Note 2), a coarse fritted-glass gas-dispersion thimble, a thermometer immersed in the liquid, and an air-cooled reflux condenser (Note 3). The outlet of the condenser is connected to a bubble counter filled with concentrated sulfuric acid this in turn is vented to the atmosphere through a water scrubber. The flask is immersed in an ice bath, and stirring is started. When the temperature of the mixture is about 10°, anhydrous hydrogen chloride is introduced through the gas-dispersion tube... 

Hydroxy-2,2,4-trimethyl-3-pentenoic acid 0-lactone, see Dimethylke-tene 8-lactone dimer Hypoiodite reaction, 46, 62... 

Pentenoic acid, physical properties, 5 31t Penthienate bromide, 4 360t Pentlandite, 17 89 Pentosans, 4 718... 

Internal olefins (2-butene, 2-hexene) were also successfully hydroformylated in water with complexes prepared in situ from [PtCbCCOD)] and the tetrasulfonated diphosphines 37 at 100 °C and 80 bar syngas [148,149]. The same catalysts were suitable for the hydroformylation of 2- and 3-pentenoic acids and trans-2-pentenenitiile, too [150]. The -... 

Structurally similar photochromic maleic anhydride derivatives 177 with a similar reaction mechanism were prepared by Irie (05CL64) by a one-pot synthesis from 2-methoxybenzothiophene, oxalyl chloride, and pentene-3-carboxylic acid (3-pentenoic acid) in dichloromethane in the presence of triethylamine at 5°C for 2 h according to Scheme 54. 

In an attempt to elaborate50 a synthetic access to DL-garosamine [126, 3-deoxy-4-C-methyl-3-(methylamino)-DL-arabinopyranose], the 1,5-lactone of 5-hydroxy-4-methyl-3-pentenoic acid (124) was oxy-aminated, to yield 2,3-dideoxy -C-methyl-3-p-toluenesulfonamido-DL-enyfhro-pentono-l,5-lactone (125). Introduction of a hydroxyl... 

DSM jointly with Du Pont de Nemours308 have patented platinum catalysts generated from the water soluble sulfonated ligand 30 (Table 2 m=0, n=0, m=l, n=2 m=l, n=l, Ar=nBu-S03Li) and used in the aqueous phase hydroformylation of internally unsaturated carboxylic acids, esters or nitriles to their corresponding formyl derivatives which are useful intermediates for the preparation of di-carboxylic acids (e.g. adipic acid). For example, TOFs up to 105 h-1 were achieved in the hydroformylation of 3-pentenoic acid catalysed by Pt/30 (m=0, n=0) at 100°C and 80 bar CO/H2 to give aldehydes with a selectivity of 83% (n/i=3.4), valeric acid (4.6%) and adipic acid (8.1%).308 The products were separated from the aqueous catalyst solution by extraction with ether. Five recycles of the aqueous catalyst solution showed that the Pt/30 (m=0, n=0) catalyst retains its activity. 

ETHYL (1-ETHYLPROPEN YL)-METHYLCYAN OACETATE (3-Pentenoic acid, 2-cyano-3-ethyl-2-methyl-, ethyl ester)... 

Both [Pd(OAc)2] and [Pd(acac)2] were used as catalyst precursors, in the presence of PPh3 or PBun3. No catalysis occurred here in absence of the phosphorus ligand. When isoprene was carbonylated using [Pd(OAc)2] and PPh3 as catalyst precursor, dimerization of the alkene did not take place, the ester of 4-methyl-3-pentenoic acid being formed as the only product.529... 

A wide variety of unsaturated carboxylic acids have been allowed to react with HBr.101 Carboxylic acids with remote C—C double bonds react as simple alkenes.138,139 4-Pentenoic acid reacts with HBr neat or in a polar solvent to give exclusively 4-bromopentanoic acid, but the reaction in nonpolar solvents affords only 5-bromopentanoic acid.136 On the other hand, 5-methyl-4-hexenoic acid produces only the S-bromo acid. A similar pattern is followed by 3-butenoic, 3-pentenoic and 4-methyl-3-pentenoic acids. No matter what the substitution pattern, 2-alkenoic acids always favor the 3-bromo acid.113,136,140,141 Addition of HBr to cyclic a,3-unsaturated acids initially forms predominantly the product of trans diaxial addition which upon longer reaction time or higher temperature isomerizes to the trans product (equation 92).57,141,142 Similar observations have been made on bicyclic a.fj-unsaturated acids.141... 

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