CARBONATES DE MONO-ACYLOXY (OU AROYL-OXY) ALCYLENES

PROCESS FOR THE PREPARATION OF MONO-ACYLOXY (OR AROYL-OXY) ALKYLEN-CARBONATES AND PRODUCTS OBTAINED

Abrégé anglais

ABSTRACT OF THE DISCLOSURE:
Process for the preparation of alkylencarbonates
of the formula:
<IMG>
wherein R1 and R2 each represent a hydrogen atom,and R
represents a lower alkyl radical consisting of reacting
compounds of the type
<IMG>
wherein R1 and R2 have the aforesaid meanings and Y represents
a halogen atom, with an alkaline or alkaline earth metal salt
of a carboxylic acid RCOOH wherein R has the aforesaid meainings,
in presence of that acid itself and the products obtained
thereof. These products are useful as intermediates for numerous
organic synthesis, such as for the preparation of .beta.-hydroxy-
aminoacids or .alpha., .alpha., .beta.-tri-acyl (aroyl) oxy-derivatives.

Revendications

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. Alkylen-carbonates of the formula
<IMG>
wherein R1 and R2 each represents a hydrogen atom, and R
represents a lower alkyl radical.
2. A process for the preparation of alkylencarbonates
of the formula
<IMG>
wherein R1 and R2 each represents a hydrogen atom, and R repre-
sents a lower alkyl radical, consisting of reacting compounds
of the type
<IMG>
wherein R1 and R2 have the aforesaid meanings and Y represents
a halogen atom, with an alkaline or alkaline earth metal salt of

a carboxylic acid RCOOH wherein R has the aforesaid meanings,in
presence of that acid itself.
3. A process according to claim 2, characterized by the
fact that the reaction is carried out at temperatures ranging from
100 to 200°C.
4. A process according to claim 2 or 3, characterized
by the fact that the reaction is carried out at a pressure ensuring
the reaction mixture to be in liquid phase.

Description

~Z~(36
The present invention relates to a process for the
preparation of mono-acyloxy (or aroyloxy~ alkyle~ carbonates
having the general formula
R~ OCOR
2 ~ H
O~f
O
wherein Rl and R2 each represents a hydrogen atom and R
represents a lower alkyl radical, and to the products obtained
thereof.
The products according to the invention are useful
as intermediates for organic synthesis, such as for the prepa-
ration of ~-hydroxy-aminoacids or ~ -tri-acyloxy
(or tri-aroyl-oxy) derivatives.
The process according to the invention is carried
out by reacting compound of the formula
Rl y
R2~H
O /0
wherein R and R have the above mentioned meanings and Y
represents a halogen atom with an alkaline or alkaline-earth
salt of a carboxylic acid RCOOH wherein R has the aforesaid
meanings, in presence of the acid itself.
The reaction is carried out at temperatures between
100 and 200C and at such pressures to ensure the reaction
medium is kept in liquid phase.
. . .

~ 0429~6
~ he invention will be now better understood with refe-
rences to the following non restrictive example.
EXAMP~E
Preparation o~ monoacetoxye-th;glencarbonate Irom monochloroeth;,rlen-
carbonate
~ o 100 of glacial acetic acid were added 9,19 g (75
~nmoles) of monochloroethylencarbonate and 7,36 g (75 mmoles) of
anhydrous potassium acetate and the mixture was heated to reflwc
for 15 hours under stirring ~d protection from the atmospheric
1û moisture. A gaschromatography test (through internal standard,
ethylencarbonate) showed a yield of monoacetoxyethylencarbonate
of 85 %. ~he reaction mixture was cooled at the room temperature
a;nd filtered. ~he precipitate was washed with aryl ether and the
collected filtrates concentrated under vacuum with a rotating
evaporator until half the initial volume was obtained. About a
double volume of ethyl ether was added, to precipitate the resi-
dual salts which were filtered and washed with ethyl ether. ~he
collected filtrates were again concentrated under vacuum with the
rotating evaporator until an oily residue was obtained, which was
20 purified by distillation. The monoacetoxyethylencarbonate dis-
tilled at 132-4C/3 mmHg (172C bàth) leaving a substantial carbon
residue in the boiler. 5.50 g of product (thick oil) were obtained,
the i.r. spectrum (film) of which showed bands atJmax 1820 (C30 of
carbonate), 1758 (c=a of acetate), 1230 (C=0 of acetate), 1160,
1090, 995 cm 1 (C=0 o~ carbonate rwith respect to the i.r. spec-
trums of cyclic carbonates, see J. ~. Hales et al., J. Chem. Soc.,
618 (1957) ;7 and the n.m.r. spectrum (C6D6) of which showed band at
~ 1.55 (s, 3H, CH3), 3.60 (d, 2H, CH2) and 6.10 p.p.m. (t, 1H,
CH)-