Furfural: Cannizzaro reaction with

Furfural undergoes the Cannizzaro reaction (compare Benzaldehyde Section IV,123) when treated with sodium hydroxide solution ... 

Furfural can be oxidized to 2-furoic acid [88-14-2] reduced to 2-furanmethanol [98-00-0] referred to herein as furfuryl alcohol, or converted to furan by decarbonylation over selected catalysts. With concentrated sodium hydroxide, furfural undergoes the Cannizzaro reaction yielding both 2-furfuryl alcohol and sodium 2-furoate [57273-36-6]. 

Furylcarbinol has been prepared by the reduction of furfural with sodium amalgam but the Cannizzaro reaction is the better practical method of preparation. 

There was also a Cannizzaro reaction that gives rise to an accident. During a reaction that was carried out by using furfural this compound came into contact with sodium hydrogencarbonate that is used to check pHs. This compound catalysed a Cannizzaro reaction that couid not be controlied and caused the compounds to combust ... 

Several cases of spontaneous ignition after exposure to air of fine coke particles removed from filter strainers on a petroleum refinery furfural extraction unit have been noted. This has been associated with the use of sodium hydrogen carbonate (bicarbonate) injected into the plant for pH control, which produced a pH of 10.5 locally. This would tend to resinify the aldehyde, but there is also the possibility of a Cannizzaro reaction causing conversion of the aldehyde to furfuryl alcohol and furoic acid. The latter, together with other acidic products of autoxidation of the aldehyde, would tend to resinily the furfuryl alcohol. Pyrolysis GLC showed the presence of a significant proportion of furfuryl alcohol-derived resins in the coke. The latter is now discarded into drums of water, immediately after discharge from the strainers, to prevent further incidents. 

MP 42, 333-42(1960) CA 55, 14421(1961) (Prepn from furfural formaldehyde with NaOH in 80% yield — Cannizzaro reaction)... 

The Cannizzaro reaction of heterocyclic aldehydes has been examined in a few cases only. Furfural,83 a-thiophenealdehyde,84 and a-pyridylal-dehyde 86 undergo the reaction normally to give the expected products. 3-Formyl-l,2,5,6-tetrahydro-l-ethylpyridine resinifies upon treatment with potassium hydroxide,86 a behavior consistent with the observation that it is structurally similar to an a,/3-unsaturated alicyclic aldehyde. 3,4-Dibromothiophene-2,5-dialdehyde undergoes a complex series of reactions, involving both cleavage (loss of —CHO) and dismutation, when treated with alkali.87 Of particular interest in this connection is the fact that under certain conditions the ester composed of the usual... 

The Cannizzaro ruction with benzaldehyde is described in a number of manuals of organic laboratory practice. The preparation of penta-erythritol (p. 101) and the conversion of furfural into furfuryl alcohol and furoic acid are described in Organic Syntheses.83 Below are a few typical examples of the reaction covering a number of the modifications discussed in the foregoing pages. 

The furoic acid may be obtained from furfural by means of the Cannizzaro reaction 2 or by oxidation with alkaline potassium permanganate.3 It is important to purify the furoic acid to a melting point of 131-132°. 

The customary process for making furoic acid starts with a Cannizzaro reaction between furfural and aqueous sodium hydroxide [74] to yield furfuryl alcohol and sodium 2-furancarboxylate ... 

K2CO3. No side reactions like the Cannizzaro or Knoevenagel reactions are observed on treatment with C-200. In the reaction with benzaldehyde and furfural the products 71 (R = Ph and 2-furyl) are formed nearly quantitatively. Bulky aromatic aldehydes such as pyrene-l-carboxaldehyde and aliphatic aldehydes are also suitable substrates for this process. ( )-acyclic a,/ -unsaturated ketones 74 can be prepared by use of a similar HWE reaction of 2-oxoalkanephosphonates 72 with aliphatic aldehydes 73 under the influence of barium hydroxide C-200 (Scheme 5.14) [36]. The HWE procedure employing activated Ba(OH)2 is applicable to the structurally complex, base-sensitive aldehydes which are susceptible to elimination and/or epimerization under the traditional basic conditions of the HWE reaction using NaH. For instance, when phosphonate 75 and aldehyde 76 are exposed to 0.8 equiv. activated Ba(OH)2 in aqueous THF at 20°C, (//-enone 77 is obtained in 70% yield (Scheme 5.14) [37]. 

Problem 9.1. Predict the product(s) of the treatment of furan-2-carbaldehyde (furfural) with base under the conditions of the Cannizzaro reaction. 

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