Methoxymethylfurfural Hydroxymethylfurfural (HMF), also known as 5-(hydroxymethyl)furfural, is an organic compound formed by the dehydration of reducing sugars.

[4][5] It is a white low-melting solid (although commercial samples are often yellow) which is highly soluble in both water and organic solvents.

The molecule consists of a furan ring, containing both aldehyde and alcohol functional groups.

Its formation has been the topic of significant study as HMF was regarded as being potentially carcinogenic to humans.

[8][9] It is also produced industrially on a modest scale[10] as a carbon-neutral feedstock for the production of fuels[11] and other chemicals.

[13] This remains the classical route, with 6-carbon sugars (hexoses) such as fructose undergoing acid catalyzed poly-dehydration.

Similar chemistry is seen with 5-carbon sugars (pentoses), which react with aqueous acid to form furfural.

[10] Numerous synthetic technologies have been developed, including the use of ionic liquids,[17][18] continuous liquid-liquid extraction, reactive distillation and solid acid catalysts to either remove the HMF before it reacts further or to otherwise promote its formation and inhibit its decomposition.

[20][21] HMF can be converted to 2,5-dimethylfuran (DMF), a liquid that is a potential biofuel with a greater energy content than bioethanol.

Here, as well as in vinegars, jams, alcoholic products or biscuits, HMF can be used as an indicator for excess heat-treatment.

Adding bases such as soda ash or potash to neutralize the HFCS slows the formation of HMF.

Photometric test may be unspecific as they may detect also related substances, leading to higher results than HPLC-measurements.