Triethoxymethane

Orthoesters are trivially named as derivatives of ortho acids such as triethyl orthoformate [122-51 -0] HC(OC2H )2, or named systematically as ethers, 1,1,1-triethoxymethane. 

Triethyl orthoformate (1,1,1-triethoxymethane) [122-51-0] M 148.2, m 30°, b 60°/30mm, 144-146°, d 0.891, n 1.392. Fractionate first at atm press, then in a vac. If impure, then wash with H2O, dry over anhyd K2CO3, filter and fractionate through a Widmer column. [Sah and MaJ Am Chem Soc 54 2964 1932 Ohme and Schmitz Justus Liebigs Ann Chem 716 207 1968.] IRRITANT and FLAMMABLE. 

The fact that reaction can be made to go with (25), but not with the simple R OH, is due to the ASe (c/ p. 36) value for the former being more favourable than that for the latter, which involves a decrease in the number of molecules on going from starting material to product. Both aldehydes and ketones that are otherwise difficult to convert into acetals may often be transformed by use of orthoesters, e.g. HC(OEt)3, triethoxymethane ( ethyl orthoformate ), with NH Cl as catalyst. 

Grignard reagents can also act as sources of negative carbon in displacement reactions, e.g. in the synthetically useful reaction with triethoxymethane (ethyl orthoformate, 58) to yield acetals (59) and, subsequently, their parent aldehydes (60) ... 

Experiment 5.153 TRIETHYL ORTHOFORMATE (Triethoxymethane) CHC13 + 3EtONa ------- CH(OEt)3 + 3NaCl... 

SYNS AETHON ETHONE ETHYLESTER KYSELINY ORTHOMRAVENCI (CZECH) 1,1, 1 -(METH-YLIDYNETRIS(OXY))TRIS(ETHANE) ORTHOFORMIC ACID, ETHYL ESTER ORTHOFORMIC ACID, TRIETHYL ESTER ORTHO RAVENCAN ETHYLNATY (CZECH) TRIETHOXYMETHANE TRIETHYL ORTHOFORMATE... 

After reaction of 21 with triethoxymethane to give 22, the latter is transformed stereospeciReally into 23 only the trans-isomer could be isolated. Further reactions of 23, which are not outlined in detail here, finally lead to the amino benzindolone 24. 

Q A convenietu synthesis of aldehydes involves the reaction of a Grignard reagent with triethyl orthoformate [triethoxymethane, HC(OEt),]. Suggest a mechanism for this reaction and hence explain why the reaction stops at the aldehyde stage. 

---