Synthesis Of Phenylethyl Alcohol

[Rhodium]

Synthesis Of Phenylethyl Alcohol
Clifford Shattuck Leonard

J. Am. Chem. Soc. 47, 1774-1779 (1925)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/phenethylalcohol.pdf)

Summary:
Benzyl cyanide may be obtained in a yield of 76% from benzyl chloride and sodium cyanide mixture. Stirring is an important factor in the yield. Phenylacetamide may be recovered from the extraction wash-waters. Ethyl phenylacetate may be prepared in a yield of 72% from benzyl cyanide or from phenylacetamide by a single-step hydrolysis and esterification with sulfuric acid and alcohol. The ester on reduction with sodium and absolute alcohol in the presence of toluene as a diluent gives phenylethyl alcohol in a yield of 47%. Unreduced phenylacetic acid may be recovered and re-employed for the preparation of the ester. The efficiency of this step is 85%.

Excerpt:

Many syntheses of phenylethyl alcohol are described in the literature, but few of these are of more than theoretical interest. A survey of the methods of synthesis described in the literature is appended below.



In the work outlined here attention was confined to the process of Bouveault and Blanc which involves four steps:

(1) Chlorination of toluene to benzyl chloride;
(2) The preparation of benzyl cyanide from this chloride;
(3) The hydrolysis and esterification of the cyanide giving ethyl phenylacetate;
(4) The reduction to phenylethyl alcohol.

The first step will be passed over without comment, for benzyl chloride is a readily available commercial chemical. The experimental part begins therefore, with the preparation of benzyl cyanide.

[Rhodium]

I just found an article which for some reason tells about the preparation of a lot of interesting precursors:

J. Am. Chem. Soc. 78, 584-590 (1956)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/3-Phenyl-1-propylamine.diazotization.pdf)

Diazotization of 3-Phenyl-1-propylamine

The reaction of 3-Phenyl-1-propylamine with sodium nitrite and acid gave the following products:

30% Phenyl-3-Propanol (reflux with TsOH gives Allylbenzene)
19% Phenyl-2-Propanol (mild oxidation gives P2P in high yield)
12% Allylbenzene
9% Recovered starting amine

Note: This seems very related to

Post 436273

(Aurelius: "On Diazotization and WizardX's site", Methods Discourse)


Oxidation of Allylbenzene

Allylbenzene (0.30 g., 2.5 mmoles) was stirred with 5 ml. of 98-100% formic acid and 0.9 ml of 30% hydrogen peroxide. The reaction became homogeneous in about 15 minutes and was then allowed to stand at room temperature for several hours. The formic acid was removed under reduced pressure and the residue boiled under reflux with 20% aqueous sodium hydroxide containing a little ethanol. The saponification reaction mixture was diluted with water and the 3-phenylpropane-1,2-diol removed by continuous ether extraction.

Note: Interesting - It seems like allylbenzene undergoes performic oxidation...


Oxidation of Phenyl-2-Propanol to P2P

[P2Pol] (5.5 g., 0.041 mole) was stirred overnight at room temperature with 2.8 g. (0.028 mole) of chromium trioxide in 20 ml. of 80% acetic acid. Fractionation [Anal. Chem. 20, 361 (1948)] of the crude mixture of products under reduced pressure gave 0.3 g. of benzaldehyde (octahydroxanthene derivative, m.p. 205.5-206°C), 2.0 g. of [P2P], and 1.2 g. of a mixture of [P2Pol] (p-toluenesulfonate, m.p. 90.8-91°C) and [P2P] (2,4-dinitrophenylhydrazone, m.p. 152-153°C).

Note: The mp of Phenyl-2-Propanol tosylate mentioned.

Post 102983

(Siegfried: "1-phenyl-2-tosyloxy-propane", Chemistry Discourse)


Allylbenzene

Hydrocinnamyl acetate, b.p. 133°C (18 mm.) (61 g., 0.34 mole) was passed over glass wool heated at 460-485°C. The pyrolysis product was washed with aqueous sodium carbonate solution, dried and distilled at atmospheric pressure. The yield of allylbenzene, b.p 150-160°C, was 31g (76%). On redistillation through a 36x1-cm. spinning-band column, most of the olefin was collected at 59-59.5°C.

Note: A novel synthesis of Allylbenzene?