Acetylenic Alcohols Carbinols

A relatively simple way of suppressing hydroxyl bond cleavage while maintaining high alkene yield is to add small quantities of sodium or potassium hydroxide to the reaction mixture. This was used to good effect in the formation of an alkenic diol, for example [63]  

The beneficial action is thought to arise from the neutralization of acid sites on the catalyst support which may otherwise promote hydrogenolysis. In this context the alkaline-earth oxide supports CaC03 and BaC03 have been used with success to inhibit the hydrogenolysis of allylic alcohols and acetates [64,65]. 

The ubiquitous Lindlar catalyst has also been used for successful reduction of alkyne function alone in a compound with additional unsaturation in the form of a double bond [66]  

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Acetylenic carbinols are prepared by the interaction of sodium acety-lides or acetylenic Grignard reagents with aldehydes. The formation and reaction of the metallic acetylide may be combined into a single operation. For example, an alkylacetylene in ether solution is treated successively with ethylmagnesium bromide and formaldehyde to give the acetylenic alcohol such as 2-heptyn-l-ol (82%). ... 

The method has been extended to the preparation of difunctional compounds. Dihalides Including the mixed variety are formed in 90 to 98% yields. Primary unsaturated bromides of the type RCH=CHCH,Br have been formed from the corresponding alcohols by the action of phosphorus tribromide and pyridine at a low temperature without any apparent rearrangement. However, the corresponding secondary-carbinol system, RCHOHCH=CH is very susceptible to allylic isomerization. The formation of a, -acetylenic bromides from acetylenic alcohols and phosphorus tribromide is common (40-70%). An acetylenic-allenic isomerization has been observed, viz.,... 

There are only a couple of examples of the Pd-catalyzed annulation of terminal acetylenic alcohols. u-Iodobenzyl alcohol reacts with acetylenic carbinols in the presence of catalytic amounts of PdCl2(PPh3)2 and Cul, plus Et3N, to produce l-alkylidene-l,3-dihydroisobenzofurans (Eq. 2) [3]. 

Bentley, R. K., D. Bhattacharjee, Sir R. H. Jones, and V. Thaller Natural Acetylenes. Part XXVIII. C-17-Polyacetylenic Alcohols from the Umbellifer Daucus carota L. (Carrot) Alkylation of Benzene by Acetylene (Vinyl) Carbinols in the Presence of Toluene-/ -sulphonic Acid. J. Chem. Soc. Section C (London) 1969, 685. 

Brinkmeyer and Kapoor (101) reported that the chiral hydride complex formed from LAH and (+ )-90 (Darvon alcohol) gave high enantiomeric ratios of chiral propargylic carbinols in the reduction of acetylenic ketones (Table 10, entries... 

This preparation illustrates a general and convenient way of oxidizing secondary alcohols to ketones. The novel feature of the reaction is represented by acetone solvent which affects markedly the properties of the oxidizing agent. The reaction is very rapid (if not instantaneous), and the yields are high, the reagent rarely attacking unsaturated centers. The procedure is applicable to acetylenic carbinols, allyl and other unsaturated alcohols, and saturated carbinols. The main limitation is the low solvent power of acetone. 

Synonyms Ethynol carbinol acetylene carbinol propiolic alcohol 2-propyn-l-ol 2-propynyl alcohol... 

Although the procedure for the O-methylation of the carbinol from acetylene and acetone (exp. 2.4) gives a fair yield, it is less suitable for the O-methyladon of alcohols that are not available in large amounts. In such cases there is need for a very clean high-yield method. The procedure for the O-methylation of ethynylcyclohexanol meets this condition. Ethynylcyclohexanol can be O-lithiated quantitatively by BuLi in a mixture of THF and hexane. Since O-alkylations of lithium alkoxides in solvents of moderate polarity proceed very sluggishly (even in the case of methyl iodide), a sufficient amount of the polar DMSO has to be added as a co-solvent. The methyladon with methyl iodide can then be accomplished under relatively mild conditions and there is no indication for decomposition of the lithium carbinolate into LiCsCH and cyclohexanone. 

Asymmetric reductions. HofFmann-LaRoche chemists1 have examined in detail the asymmetric reduction of a,/(-acetylenic ketones with Darvon alcohol (1) and related alcohols. Use of the enantiomer of 1 resulted predominately in reduction to the enantiomer (S) of the (R)-carbinols obtained with 1. Several optically pure 1,3-... 

Acetylenic carbinols, which are manufactured from aldehydes or ketones and acetylenes, can be partially hydrogenated, with the exception of propargyl alcohol itself. Hydrogenolysis is a minor side reaction unless the hydrogenation is completed to the alkane. Nickel boride (PI or P2) catalysts achieve the saturation of propargyl and allylic compounds in the presence of double bonds without hydrogenolysis, such as in 2 an intermediate in the total synthesis of the sesquiterpene sesquicarene ... 

Beilstein Handbook Reference) Acetylene carbinol Agrisynth PA AI3-24359 BRN 0506003 CCRIS 6781 EINECS 203-471-2 Ethynyl carbinol HSDB 6054 1-Hydroxy-2-propyne 3-Hydroxy-1-propyne Methanol, ethynyl- NA1986 NSC 8804 Propargyl alcohol Proplolic alcohol Propynyl alcohol 1-Propyn-3-ol ... 

Structure and functional group HC=C— CH2—OH, primary hydroxyl group Synonyms propargyl alcohol acetylene carbinol... 

Acetylene black. See Carbon black Acetylene carbinol. See Propargyl alcohol Acetylene dichloride. See cis-trans-1,2-Dichloroethylene (mixed isomers) trans-Acetylene dichloride. Seetrans-1,2-Di ch I oroethy lene... 

Ethyl Zimate Slurry, Ethyl ZImate . See Zinc d iethy I d ith i ocarbam ate Ethyne. See Acetylene 2-Ethynyl-2-butanol. See Methyl pentynol Ethynyl carbinol. SeePropargyl alcohol Ethynyl cyclohexanol. See 1-Ethynylcyclohexanol 1 -Ethynylcyclohexanol CAS 78-27-3 EINECS/ELINCS 201-100-9 Synonyms Ethynyl cyclohexanol 1-Ethynyl-1-cyclohexanol 1-Ethynylcyclohexan-1-ol Empincal C8H12O Formula HC=CC6HioOH Properties Wh. cryst. solid sweet odor sol. in most org. soivs., oxygenated and aromatic soivs. insol. in water m.w. 124.20 dens. 0.967 m.p. 30-31 C b.p. 180C... 

Bentley, R.K., Bhattacharjee, D., Jones, E.R.H. et al (1969a) Natural acetylenes. Part XXVIII. Ci7-Polyacetylenic alcohols from the UmbeUifer Daucus carota L. (carrot) Alkylation of benzene by acetylenyl(vinyl)carbinols in the presence oftoluene-p-sulphonic acid. /. Chem. Soc. (C), 685-688. 

Toxicoiogy Eye, skin, and resp. tract irritant Precaution Avoid contact with moisture and strong oxidizing agents Hazardous Decomp. Prods. CO , NO , and HCI gas HMIS Health 2, Flammability 0, Reactivity 1 Uses Antioxidant In dietary supplements o-Acetyl-L-camitine hydrochloride. See Acetyl-L-camitine hydrochloride Acetylene carbinol. See Propargyl alcohol Acetylenic glycol. See Tetramethyl decynediol Acetyl ester of lanolin. See Acetylated lanolin N-Acetyl ethanolamine. See Acetamide MEA Achiote. See Annatto (Bbca orellana)... 

Synonyms Acetylene carbinol Ethynyl carbinol Ethynyl methanol 1-Hydroxy-2-propyne 3-Hydroxy-1-propyne Propiolic alcohol 1-Propyne-3-ol Propyn-1-ol 1-Propyn-3-ol 2-Propynol 2-Propyn-1-ol 3-Propynol 2-Propynyl alcohol Classification Unsat. aliphatic alcohol Empirical C3H4O Formula HC=CCH20H... 

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