Orthoformic acid trimethyl ester

Trimethyl orthoformate Orthoformic acid, trimethyl ester (8) Methane, trimethoxy- (9) (149-73-5)... 

Fig. 9.13. Mechanism of the acid-catalyzed hydrolysis of orthoformic acid trimethyl ester.

Fig. 7.17. Possible mechanism for the alcohol-free acetalization of a carbonyl compound with orthoformic acid trimethyl ester.

Trimethyl orthoformate Orthoformic acid, trimethyl ester (8) ... 

Beilstein Handbook Reference) AI3-23842 BRN 0969215 EINECS 205-745-7 HSDB 1006 Methane, trimethoxy- Methyl orthoformate Methylester kyseliny orthomravenci NSC 147479 Orthoformic acid methyl ester Orthoformic acid, trimethyl ester Orthomravencan methyinaty Trimelhoxymethane Trimethyl orthoformate Trimethylester kyseliny orthomravenci. Liquid mp = 15° bp = 104°, d O = 0.9676 soluble in EtOH, Et20. 

SYNS METHYLESTER KYSEUNY ORTHOMRAVENCI (CZECH) METHYL ORTHOFORMATE ORTHO-FORMIC ACID, TRIMETHYL ESTER ORTHOMRAVEN-CAN METHYLNATY (CZECH) TRIMETHO-XYMETHANE... 

One can also acetalize carbonyl compounds completely without using the alcohol in excess. This is the case when one prepares dimethyl or diethyl acetals from carbonyl compounds with the help of the orthoformic acid esters trimethyl orthoformate HC(OCH3)3 or triethyl orthoformate HC(OC2H5)3, respectively. In order to understand these reactions, one must first clearly understand the mechanism for the hydrolysis of an orthoester to a normal ester (Figure 7.16). It corresponds step by step to the mechanism of hydrolysis of <9,<9-acctals, which was detailed in Figure 7.15. The fact that the individual steps are really strictly analogous becomes very clear when one takes successive looks at... 

Benzoxazoles unsubstituted in the 2-position are obtained by cyclocondensation of o-aminophenols with orthoformic trimethyl ester in the presence of coned hydrochloric acid [73], e.g. ... 

A completely different concept13 makes use of a highly reduced bilane 5 which is oxidatively cyclized to an isobacteriochlorin 6 with copper(II) acetate. The ring closure is initiated by ester cleavage with trifluoroacetic acid and decarboxylative formylation with trimethyl orthoformate to yield a dialdehyde. One of the aldehyde functions forms the desired methine bridge whereas the other is lost during cyclization. 

Sulfonic esters are most frequently prepared by treatment of the corresponding halides with alcohols in the presence of a base. The method is much used for the conversion of alcohols to tosylates, brosylates, and similar sulfonic esters. Both R and R may be alkyl or aryl. The base is often pyridine, which functions as a nucleophilic catalyst, as in the similar alcoholysis of carboxylic acyl halides (10-21). Primary alcohols react the most rapidly, and it is often possible to sulfonate selectively a primary OH group in a molecule that also contains secondary or tertiary OH groups. The reaction with sulfonamides has been much less frequently used and is limited to N,N-disubstituted sulfonamides that is, R" may not be hydrogen. However, within these limits it is a useful reaction. The nucleophile in this case is actually R 0 . However, R" may be hydrogen (as well as alkyl) if the nucleophile is a phenol, so that the product is RS020Ar. Acidic catalysts are used in this case. Sulfonic acids have been converted directly to sulfonates by treatment with triethyl or trimethyl orthoformate HC(OR)3, without catalyst or solvent and with a trialkyl phosphite P(OR)3. ... 

For instance, 2-methylpropene reacted with acetic acid at 18°C in the presence of Al-bentonite to form the ester product (75). Ion-exchanged bentonites are also efficient catalysts for formation of ketals from aldehydes or ketones. Cyclohexanone reacted with methanol in the presence of Al-bentonite at room temperature to give 33% yield of dimethyl ketal after 30 min of reaction time. On addition of the same clay to the mixture of cyclohexanone and trimethyl orthoformate at room-temperature, the exothermic reaction caused the liquid to boil and resulted in an almost quantitative yield of the dimethyl ketal in 5 min. When Na- instead of Al-bentonite is used, the same reaction did not take place (75). Solomon and Hawthorne (37) suggest that elimination reactions may have been involved in the geochemical transformation of lipid and other organic sediments into petroleum deposits. 

Acetaldehyde/trimethyl orthoformate and the efficient reducing agent triacetoxyboro-hydride [NaBH(OAc)3I<13 ] were used to develop a one-pot synthesis of Al-ethyl amino acid esters 22. 114 As can be seen in Scheme 14, excess acetaldehyde was reacted with various amino acid ester in trimethyl orthoformate. The excess acetaldehyde was removed under reduced pressure and the resulting imine 21 was reduced with NaBH(OAc)3 without isolation. The yields of the isolated TV-ethyl amino acid esters 22 are high. 

Esterification of sulfonic acids.1 Sulfonic acids are converted into methyl or ethyl esters on reaction with trimethyl or triethyl orthoformate. Yields are >80% in esterification of arenesulfonic acids, but are somewhat lower in the reaction of alkanesulfonic acids because of volatility of the products. 

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