Alcohols propargyl

Propargyl alcohol (2-propyn-l-ol, boiling point 114°C) is a colorless volatile liquid with an unpleasant odor that is the only commercially available acetylenic primary alcohol. It is miscible with water and with many organic solvents. The commercial material is specified as 97% minimum purity, determined by gas chromatography or acetylation. Moisture is specified at 0.05% maximum (Karl-Fischer titration). Formaldehyde content is determined by bisulfite titration. 

Propargyl alcohol is a component of oil-well acidizing compositions, inhibiting the attack of mineral acids on steel, and is also employed in the pickling and plating of metals. 

Propargyl alcohol is used as an intermediate in preparation of the miticide Omite 2-(4 -tert-butylphenoxy)cyclohexyl 2-propynyl sulfite, of sulfadiazine, and of halogenated propargyl carbonate fungicides. 

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  

Halogenating agents can be used to replace hydroxyl with chlorine or bromine. Phosphorus trihalides, especially in the presence of pyridine, are particularly suitable, and propargyl iodide is easily prepared from propar-gyl bromide by halogen exchange. 

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To absolution of 1.00 mol of ethyl lithium in 800-900 ml of diethyl ether (see Chapter II, Exp. 1) was added, with cooling between -20 and -10°C, 0.50 nol of dry propargyl alcohol, dissolved in 100 ml of diethyl ether. Subsequently 1.1 mol of trimethylchlorosilane was introduced over a period of 25 min with cooling between -15 and +5°C. After stirring for an additional 2 h at about 30°C the suspension was poured into a solution of 30 g of acetic acid in 150 ml of water. After stirring for 1 h at room temperature the layers were separated and the aqueous layer v/as extracted four times with diethyl ether. The combined ethereal solutions were washed with sodium hydrogen carbonate solution in order to neutralize acetic acid, and were then dried over magnesium sulfate. The diethyl ether was removed by evaporation in a water-pump vacuum and the residue distilled... 

Butyllithium in a mixture of hexane and diethyl ether or THE can presumably also be used for the dilithiation of propargyl alcohol. 

To a vigorously stirred suspension of 4 mol of lithium amide (see II, Exp. II) in 2.5 1 of liquid ammonia were added in 25 min 2 mol of propargyl alcohol (commercially available, purified before use by distillation at 100-120 mm). The suspension became very thin. Subsequently, the dropping funnel was combined with a gas inlet tube reaching about 1 cm beneath the surface of the ammonia. The vent on the splashing tube was removed. Methyl iodide (2 mol) was added to the vigorous-... 

To a vigorously stirred suspension of 2 mol of lithium amide in 2 1 of liquid atimonia (see II, Exp. 11) was added in 15 min 1 mol of propargyl alcohol (commercial product, distilled in a partial vacuum before use). Subsequently, 1 mol of butyl bromide was added dropwise in 75 min. After an additional 1.5 h, stirring was stopped and the ammonia was allovied to evaporate. To the solid residue were added 500 ml of ice-water. After the solid mass had dissolved, six extractions with diethyl ether were performed. The (unwashed) combined extracts were dried over magnesium sulfate and then concentrated in a water-pump vacuum. Distillation of the residue through a 40-cm Vigreux column afforded 2-heptyn-l-ol, b.p. 

Mote 2. The change in the green colour can be ascribed to the formation of Cu(0H)C1, when the propargyl alcohol has been completely converted. 

Propargyl alcohol gives a 70 30 mixture of iodoallene and propargyl iodide. For... 

A well known, synthetically useful reaction of propargylic alcohols is their... 

Note 1. The sulfinate of propargyl alcohol did not rearrange upon heating at 130-140°C in xylene. 

To a mixture of 100 ml of dry dichloromethane, 0.10 mol of propargyl alcohol and 0.11 mol of triethylamine was added a solution of 0.05 mol of Ph2PCl in 75 ml of dichloromethane in 3 min between -80 and -90°C. The cooling bath was removed, and when the temperature had reached 10°C, the reaction mixture was poured into a solution of 2.5 ml of 362 HCl in 100 ml of water. After vigorous shaking the lower layer was separated and the aqueous layer was extracted twice with 25-ml portions of dichloromethane. The combined solutions were washed twice with water, dried over magnesium sulfate and then concentrated in a water-pump vacuum, giving almost pure allenyl phosphine oxide as a white solid, m.p. 98-100 5, in almost 1002 yield. 

To a mixture of 65 ml of dry benzene and 0.10 mol of freshly distilled NN-di-ethylamino-l-propyne were added 3 drops of BFa.ether and 0.12 mol of dry propargyl alcohol was added to the reddish solution in 5 min. The temperature rose in 5-10 min to about 45°C, remained at this level for about 10 min and then began to drop. The mixture was warmed to 60°C, whereupon the exothermic reaction made the temperature rise in a few minutes to B5 c. This level was maintained by occasional cooling. After the exothermic reaction (3,3-sigmatropic rearrangement) had subsided, the mixture was heated for an additional 10 min at 80°C and the benzene was then removed in a water-pump vacuum. The red residue was practically pure acid amide... 

Aconitatc was obtained as a minor product in the carbonylation of propar-gyl alcohol[479]. However, in the two-step synthesis of methyl aconitate (536) from propargyl alcohol in 70% overall yield, the first step is the oxidative carbonylation under CO and air using Pdli and KI to giNe dimethyl hydro-xymethylbutenedioate (535), which is carbonylated further to give trimethyl aconitate (536) by u.sc of [Pd(Tu)4jl2 as a catalyst[480]. 

As an application of maleate formation, the carbonylation of silylated 3-butyn-l-ol affords the 7-butyrolactone 539[482], Oxidative carbonylation is possible via mercuration of alkynes and subsequent Lransmetallation with Pd(II) under a CO atmosphere. For example, chloromercuration of propargyl alcohol and treatment with PdCF (1 equiv.) under 1 atm of CO in THF produced the /3-chlorobutenolide 540 in 96% yield[483]. Dimethyl phenylinale-ate is obtained by the reaction of phenylacetylene, CO, PdCU, and HgCl2 in MeOH[484,485]. 

Acetylene is also protected as propargyl alcohol (300)[2H], which is depro-tected by hydrolysis with a base, or oxidation with MnOi and alkaline hydrolysis. Sometimes, propargyl alcohols are isomerized to enals. Propargyl alcohol (300) reacts with 3-chloropyridazine (301) and EtiNH to give 3-diethylami-noindolizine (303) in one step via the enal 302[2I2]. Similarly, propargyl alcohol reacts with 2-halopyridines and secondary amines. 2-Methyl-3-butyn-2-ol (304) is another masked acetylene, and is unmasked by treatment with KOH or NaOH in butanol[205,206,213-2l5] or in situ with a phase-transfer cata-lyst[2l6]. 

Pyrrole derivatives are prepared by the coupling and annulation of o-iodoa-nilines with internal alkynes[291]. The 4-amino-5-iodopyrimidine 428 reacts with the TMS-substituted propargyl alcohol 429 to form the heterocondensed pyrrole 430, and the TMS is removed[292]. Similarly, the tryptophane 434 is obtained by the reaction of o-iodoaniline (431) with the internal alkyne 432 and deprotection of the coupled product 433(293]. As an alternative method, the 2,3-disubstituted indole 436 is obtained directly by the coupling of the o-alky-nyltrifluoroacetanilide 435 with aryl and alkenyl halides or triflates(294]. 

Propargylic (or 2-alkynyl) compounds are derivatives of alkynes. However, Pd-catalyzed reactions of propargylic derivatives, particularly esters and halides, are very different mechanistically from those of simple alkynes, except in a few cases. Therefore, the reactions of propargylic esters and halides are treated in this section separately from those of other alkynes. However, some reactions of propargylic alcohols, which behave similarly to simple alkynes, are treated in Section 6. 

Propargylic alcohols are less reactive and their carbonylation proceeds under severe conditions. The Pd-catalyzed carbonylation of propargyl alcohol in the... 

Propargylic alcohol, after lithiation, reacts with CO2 to generate the lithium carbonate 243, which undergoes oxypalladation. The reaction of allyl chloride yields the cyclic carbonate 244 and PdC. By this reaction hydroxy and allyl groups are introduced into the triple bond to give the o-allyl ketone 245[129]. Also the formation of 248 from the keto alkyne 246 with CO2 via in situ formation of the carbonate 247 is catalyzed by Pd(0)[130]. 

Propargyl Alcohol. Propargyl alcohol [107-19-7] 2-propyn-l-ol, C H O, is the only commercially available acetylenic primary alcohol. A... 

Rea.ctlons, Propargyl alcohol has three reactive sites—a primary hydroxyl group, a triple bond, and an acetylenic hydrogen—making it an extremely versatile chemical intermediate. 

In the presence of suitable nickel or cobalt complexes, propargyl alcohol trimerizes to a mixture of l,3,5-ben2enetrimethanol [4464-18-0] and 1,2,4-trimethanol [25147-76-6] hen-zene (28). 

Nickel halide complexes with amines give mixtures of linear polymer and cychc trimers (30). Nickel chelates give up to 40% of linear polymer (31). When heated with ammonia over cadmium calcium phosphate catalysts, propargyl alcohol gives a mixture of pyridines (32). 

In the presence of copper acetyhde catalysts, propargyl alcohol and aldehydes give acetylenic glycols (33). When dialkylamines ate also present, dialkylaminobutynols are formed (34). 

With two equivalents of an organomagnesium hahde, a Gtignard reagent is formed, capable of use in further syntheses (35,36). Cuprous salts cataly2e oxidative dimerization of propargyl alcohol to 2,4-hexadiyne-l,6-diol [3031-68-3] (37). 

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