Principal 2
Ubichem is pleased to announce they are distributing a range of Glymes for Clariant UK. Please contact mark.roberts@ubichem.com or andrew.calvert@ubichem.com for more details on the full range of glymes.
GLYMES
Polyethylene glycol (PEG) dialkyl ethers
Versatile Functional Solvents in Chemical Syntheses
1.0 Introduction
These are speciality solvents which provide cost effective alternative in phase transfer catalysts, enhancing reactivity and yield in reduction reactions; additionally they provide a low toxic, low flammable alternative in Grignard reactions with both organic and inorganic systems. The high solvency of the "Glyme" family means that they can be used with polymers such as polyesters, PVC etc as well as replacements for toxic, flammable and organic solvents.
"Glymes" is the trivial name use to refer to Ethyleneglycol dimethyl ethers (also abbreviated as PEG DME). They are dipolar, aprotic, chemically inert solvents, exerting good thermal stability, miscible with most organic solvents and miscible with water (except butyl glymes). They are non toxic and have low flammability. They exhibit high dissolving power for inorganic salts such as NaF, NaBH4, transition metal salts etc and for polymers and plastics.
Table 1: Synonyms of Polyglycol dimethyl ethers
| Clariant's name | CAS-No. | Synonyms |
| Monoethylene glycol DME | 110-71-4 | Monoglyme, 1,2-Dimethoxyethane |
| Diethylene glycol DME | 111-96-6 | Diglyme |
| Triethylene glycol DME | 112-49-2 | Triglyme |
| Tetraethylene glycol DME | 143-24-8 | Tetraglyme |
| Polyglycol DME | 24991-55-7 | Polyethylenglycol dimethylether (number = molecular weight) |
| Diethylenglycol dimethylether | 112-73-2 | Butyl diglyme |
| Genosorb-Types | var. | |
| Dipropylenglycol dimethylether | 111109-77-4 | Proglyme |
Table 2: Properties of Polyglycol dimethyl ethers
| name | Boiling point [°C] | Ignition temp. [°C] | Viscosity [mm2/s] | evap. rate [Et2O=1] |
| Monoethylene glycol DME | 85 | 200 | 0.45 | ca. 3 |
| Diethylene glycol DME | 162 | 190 | 1.2 | 90 |
| Triethylene glycol DME | 216 | 195 | 2.5 | 2100 |
| Tetraethylene glycol DME | 275 | 195 | 4.1 | >3000 |
| Polyglycol DME 250 | >300 | 210 | 7.5 | >3000 |
| Polyglycol DME 500 | >300 | 360 | 25 | >3000 |
| Polyglycol DME 1000 | >300 | 405 | waxy | >3000 |
| Polyglycol DME 2000 | >300 | 385 | waxy | >3000 |
Table 3: Azeotropic mixtures with monoglyme
| Composition [m/m] | b.p. [°C] | |
| Water | 10% water | 78.5 |
| Methanol | 92% methanol | 63-64 |
| Ethanol | 50% ethanol | 77.3 |
| Chloroform | 22% chloroform | 85.7 |
| n-Hexane | 79% hexane | 67.9 |
Table 4: Azeotropic mixtures with diglyme
| Composition [m/m] | b.p. [°C] | |
| Water | 77% water | 99.3 |
| Phenol | 62% phenol | 189.0 |
2.0 Usage and benefits of Glymes in Organic Synthesis
2.1 Phase transfer catalysts
Because of their dipolar nature Glymes will tend to behave as linear Crown Ethers, they are miscible with most organic solvents and dissolve inorganic salts. Their usefulness as coordinating agents/solvents means that inorganic salts can be transferred from the aqueous to the organic phase with the help of Glymes. This is called Phase transfer catalysis. The benefit of using PEG DMF in KMnO4 oxidation and nucleophilic exchange is demonstrated here. Some of the other benefits of using Glymes as PTC are:
- Non toxic (unlike crown ethers)
- Thermal stability (unlike Quats)
- May be used in a wide pH range (unlike Quats)
- Cost effective (unlike crown ethers)
- May be used as a solvent (unlike Quats and crown ethers)
- Best catalytic activity: Polyglycol DME 1000 and 2000 (dosage 1-5%)
