Description
Dipentaerythritol, also known as 2,2-[oxybis(methylene)- bis[2-hydroxymethyl]-1,3-propanediol, is a byproduct of pentaerythritol production. Because of its low solubility in water (0.22 g/ 100 g H2O at 20 ℃ and 10.0 g/100 g H2O at 100 ℃) it can be separated from pentaerythritol by fractional crystallization. The yield can be increased by changing the ratio of formaldehyde/ acetaldehyde towards stoichiometric. Adding pentaerythritol before starting the reaction also increases the yield. An effective method is to use acrolein instead of acetaldehyde. Dipentaerythritol can be produced intentionally from pentaerythritol by acid catalysis. Dipentaerythritol is purified as a coproduct by many pentaerythritol producers.
Chemical Properties
white crystalline powder
Uses
2,2''-(Oxybis(methylene))bis(2-(hydroxymethyl)-propane-1,3-diol) is used in preparation of new type of explosion-proof and flame-retardant tape material for cables.
Application
PVC stabilizers based on calcium – zinc carboxylates use micronized dipentaerythritol as costabilizer to improve the thermal stability of PVC during processing. This system grows fast in economic significance at the expense of leadbased stabilizers due to environmental reasons. Micronized dipentaerythritol is also used in intumescent paints. Synthetic lubricants are another important application for dipentaerythritol. The C5 – C10 esters are used as lubricants in jet engines and refrigerators. Rosin esters made from dipentaerythritol have a higher softening point than rosin esters from pentaerythritol.
Application
Dipentaerythritol (DPE) is an attractive raw material used for the production of polyesters, polyethers, polyurethanes, alkyd resins, photosensitive resin film. DPE is also employed in a wide range synthesis of specialty chemicals such as lubricants, coatings, adhesives, plasticizers and cosmetics.
Preparation
Dipentaerythritol is obtained as a byproduct in the manufacture of pentaerythritol; it is separated by fractional distillation.
Dipentaerythritol (DPE) has been prepared from a slurry of Pentaerythritol (PE) in sulfolane catalyzed by a low amount of sulfuric acid and was isolated with 16% yield (72% GPC purity) and 57% isolated selectivity.
synthesis of dipentaerythritol from pentaerythritol under acidic conditions
Flammability and Explosibility
Not classified
Synthesis
The general procedure for synthesizing dipentaerythritol from pentaerythritol (PET) is as follows: in a reaction flask equipped with a stirrer, a thermometer, a distillation column, and a condenser tube, 350 parts of pentaerythritol (PET), 182 parts of ethylidene carbonate, and 0.3 parts of tetrabutoxytitanium as a catalyst (trade name: Orgatics TA-25, produced by Matsumoto Fine Chemical Co.) Subsequently, 0.3 part of boron trioxide was added as a co-catalyst. The reaction mixture was heated to 140-170 °C and the reaction was stirred in this temperature range for 11 hours. During the reaction, the system pressure was maintained at 0.055-0.0001 MPa while the generated ethylene glycol and unreacted ethylene carbonate were removed from the system by means of a distillation column and a condensation tube. Upon completion of the reaction, 250 parts of pentaerythritol (PET), 3.2 parts of diboron trioxide (as Catalyst B) and 1.6 parts of sodium formate (as Catalyst A) were added to the same flask. The reaction mixture was heated to 190 °C and the reaction was stirred at 0.097 MPa for 3 hours. At the end of the reaction, the products were analyzed and the results are shown in Table 2.
References
[1] Patent: JP5896028, 2016, B2. Location in patent: Paragraph 0065; 0077
[2] Patent: US6121499, 2000, A
[3] Patent: CN104220415, 2016, B. Location in patent: Paragraph 0102-0108
