Propynal acetal Propyne

A mixture of 0.10 mol of 1-ethylthio-l-propyne (see IV, Exp. 23 and Ref. 1) and 100 ml of glacial acetic acid was heated at 95°C, then 35 ml of 33% hydrogen peroxide were added in 15 min with occasional cooling. After this addition the mixture was kept for 1 h at 100°C, then cooled to 20°C and 200 ml of water were added. Ten extractions with 20-ml portions of chloroform were carried out and the combined extracts were dried over magnesium sulfate (without previous washing)... 

Alkynes with EWGs are poor substrates for the coupling with halides. Therefore, instead of the inactive propynoate, triethyl orthopropynoate (350) is used for the coupling with aryl halides to prepare the arylpropynoate 351. The coupling product 353 of 3,3-dicthoxy-l-propyne (352) with an aryl halide is the precursor of an alkynal[260]. The coupling of ethoxy) tributylstan-nyl)acetylene (354) with aryl halides is a good synthetic method for the aryl-acetate 355[261]. 

Propargyl alcohol (2-propyn-l-ol) [107-19-7] M 56.1, b 54 /57mm, 113.6 /760mm, d 0.947, n 1.432. Commercial material contains a stabiliser. An aqueous soln of propargyl alcohol can be concentrated by azeotropic distn with butanol or butyl acetate. Dried with K2CO3 and distd under reduced pressure, in the presence of about 1% succinic acid, through a glass helices-packed column. 

Propiolaldehyde, 3-chloro-, diethyl acetal (8) 1-Propyne, 1-chloro-3,3-diethoxy- (9) (62761-29-9)... 

Carbonylation of methanol to acetic acid is fully discussed in Chapter 9. Another carbonylation process using a phosphine ligand to control the course of the reaction is a highly atom efficient route to the widely used monomer methyl methacrylate (Scheme 4.19). In this process the catalyst is based on palladium acetate and the phosphine ligand, bisphenyl(6-methyl-2-pyridyl) phosphine. This catalyst is remarkably (>99.5%) selective for the 2-carbonylation of propyne under the relatively mild conditions of <100 °C and 60 bar pressure. 

Propanol Propene Propyl acetate Propylbenzene Propyl formate Propyl nitrate Propyne Pyridine Quinoline Sodium Styrene... 

Bowman et al. reported the total synthesis of ellipticine (228) involving an imidoyl radical cascade reaction (730). For this key step, the required imidoyl radical was generated from the imidoyl selanide 1290, which was obtained from ethyl 2-(4-pyridyl)acetate (1286). Reaction of 1286 with LDA, followed by addition of methyl iodide, led to the corresponding methyl derivative 1287. Treatment of 1287 with 2-iodoaniline (743) in the presence of trimethylaluminum (AlMes) afforded the amide 1288. Using Sonogashira conditions, propyne is coupled with the amide 1288 to afford the aryl acetylene 1289. The aryl acetylene 1289 was transformed to the... 

The so-called trimerization of propynal in the presence of piperidine acetate provides a synthesis of 4-ethynyI-4//-pyran-3,5-dicarbaldehyde (149) (50LA(568)34> it should be noted that the structure proposed for the product in the original work has been corrected (64CB1959). In the absence of moisture, the reaction fails and it seems likely that the synthesis involves hydration of the alkyne to the divinyl ether. Finally, condensation with the third molecule of the aldehyde results in cyclization to the product (Scheme 20). 

Some supporting evidence for the mechanism is provided by the formation of the 4-ethyl analogue (150) when propynal is treated with piperidine acetate in the presence of propanal the latter may be considered to intercept the divinyl ether. 

A 1,4-dipolar cycloaddition between tetrahydropyrido[l,2-a]pyrimidi-none 114 (R = Me) and 4-methyl-l, 2,4-triazoline-3,5-dione 666gave stable adduct 667 in acetonitrile or in acetic acid at room temperature for 1 hour (Scheme 44) (85CB4567). When ethyl cyanoformate was used as dienophile in boiling toluene for 20 hours, ethyl 3-methyl-4-oxo-6,7,8,9-tetrahydro-4//-pyrido[ 1,2-a]pyrimidine-2-carboxylate 669 was obtained (86CB1445). Pyrido[l,2-a]pyrimidine-2-carboxylate 669 was formed from the initial adduct 668 by elimination of phenyl isocyanate. Reaction of tetrahydropyr-ido[l,2-a]pyrimidinone 114 (R = Me) with l-(diethylamino)-l-propyne in... 

The presence of electron withdrawing substituents on the triple bond decreased the reactivity of the molecule. Using 2-thienyl-l-propyn-3-ol acetate (173) as substrate, a photochemical reaction occurred, giving the product of photoarylation 174 (94JCS(P1)1245). 

The reaction of acetylenes with CO to produce octatrienediolides has been reported (2a). In the presence of dicobalt octacarbonyl in acetic anhydride/ acetone solvent, propyne was found to react with CO to give dimethyl-octatrienediolides. Hydrogenation of the latter yielded 2,6-dimethylsuberic acid. 

The chemical properties and uses of propargyl alcohol has three potentially reactive sites (1) a primary hydroxyl group (i.e., CH2OH), (2) a triple bond (-C=C-), and (3) an acetylenic hydrogen (-C=CH) that makes the alcohol an extremely versatile chemical intermediate. The hydroxyl group can be esterified with acid chlorides, anhydrides, or carboxylic acids, and it reacts with aldehydes or vinyl ethers in the presence of an acid catalyst to form acetals. At low temperatures, oxidation with chromic acid gives propynal or propynoic acid ... 

Isopropenyl esters of N-protected amino acids. In the presence of the Ru(II) catalyst, Cbo- or Boc-amino acids add to propyne at 100° to provide isopropenyl esters in 55-85% yield with no racemization. Unprotected amino acids do not add to the alkyne. These esters react with primary amines at room temperature in ethyl acetate to afford amides in 75-90% yield. 

Methoxy 1 propyne furconazole Methyl acetoacetate see Aceto acetic acid Methyl aceto acetic acid pirimicarb... 

The NiY zeolite was also shown to be active for the cyclotrimerization of propyne with 1,2,4-trimethylbenzene being the main product. The activities of the above-mentioned transition metal ions for acetylene trimerization are not so surprising since simple salts and complexes of these metals have been known for some time to catalyze this reaction (161, 162). However, the tetramer, cyclooctatetraene, is the principal product in homogeneous catalysis, particularly when simple salts such as nickel formate and acetate are used as catalysts (161). The predominance of the trimer product, benzene, for the zeolite Y catalysts might be indicative of a stereoselective effect on product distribution, possibly due to the spatial restrictions imposed on the reaction transition-state complex inside the zeolite cages. 

The kinetics and stereochemistry of addition of HC1 to 1-phenyl-propyne and to 3-hexyne in acetic acid have been found to be different in the two cases (4 and 5 of Table 2) (Fahey and Lee, 1966,1967,1968). 

Propanedithiol (109-80-8), 65, 150 2-Propanol, titanium (4+) salt, 65, 230 2-Propanone, l-bromo-3-chloro-, dimethyl acetal, 65, 32 PROPARGYL CHLORIDE PROPYNE, 3-CHLDRD- 1-PROPYNE, 3-CHL0RD- ... 

In this chapter we discuss the mechanistic and other details of a few industrial carbonylation processes. These are carbonylation of methanol to acetic acid, methyl acetate to acetic anhydride, propyne to methyl methacrylate, and benzyl chloride to phenyl acetic acid. Both Monsanto and BASF manufacture acetic acid by methanol carbonylation, Reaction 4.1. The BASF process is older than the Monsanto process. The catalysts and the reaction conditions for the two processes are also different and are compared in the next section. Carbonylation of methyl acetate to acetic anhydride, according to reaction 4.2, is a successful industrial process that has been developed by Eastman Kodak. The carbonylation of propyne (methyl acetylene) in methanol to give methyl methacrylate has recently been commercialized by Shell. The Montedison carbonylation process for the manufacture of phenyl acetic acid from benzyl chloride is noteworthy for the clever combination of phase-transfer and organometallic catalyses. Hoechst has recently reported a novel carbonylation process for the drug ibuprofen. 

Acetone dibutyl acetal has been prepared from isopropenyl acetate and butanol, from butanol and isopropenyl butyl ether obtained from the reaction of butanol with propyne, and by orthoformic ester synthesis. ... 

---