FR2667314A1 - Prepn. of di:alkyl di:carbonate - Google Patents

Abstract

Prepn. of a dialkyl dicarbonate (I) comprises reacting (a) alkyl or aralkyl pyrocarbonate of an alkali (II: esp. Na); with (b) diacid dihalide (III); in the presence of (c) a complexing agent (IV), e.g. (i) a tert-oxygenated amine, partic. with an ether function, esp. N-(CHR'-CHR2-O-(CHR3-CHR4-O)n-R5)3 (n = integral 0-10; R1-R4 = H or 1-4C alkyl; R5 = 1-12C alkyl or cycloalkyl, phenyl or CmH2O or CmH2m+1O; m = 1- about 12); specifically tris(dioxaheptyl)amine (V); (ii) an oxygen-or sulphur-contg. polyether, cyclic or macrocyclic, e.g. diethylene glycol dimethyl ether or dioxane; or (iii) cryptands e.g. (VI) (VIII) (where Y = O, N or P; p,q,r = integer 1-5; A = 1-3C alkylene; D = O, S or R'':R10,R11 = 1-6C alkyl) with the condition that (d) when III is phosgene or di- or tri- phosgene and IV is a tert.monoamine e.g. 1,4-diazabicyclo (2,2,2)-octane, 1,8-diazabicyclo (5,4,0) undecane-7, hexamethyltetramine, N-methylpiperidine, etc. then II is Li or pref. Na.

Description

PROCESS FOR THE PREPARATION OF DICARBONATE
DIALCOYLE SECONDARY OR TERTIARY
The present invention relates to a new process for the preparation of ditertiobutyl dicarbonate. It relates more particularly to the preparation of di-tert-butyl carbonate from phosgene, diphosgene or triphosgene.

 It has long been known to prepare di-tert-butyl carbonate, often referred to as BOC2O from tert-butyl pyrocarbonate and phosgene as described, for example, by J.H.

HOWE in the Journal of Organic Chemistry 27, 1901 (1962).

It is also known, according to the article published by Pozdev, Smirnova,
Podgornova, Zentsova and Kalei in Zhurnal Urganicheskoi Khimii Vol.

15, No. 1, pages 106-109 in 1979 and translated in the Journal of Organic
Chemistry USSR 1979, page 95, to prepare di-tert-butyl carbonate by condensation of tert-butyl carbonate with an acid chloride in a mixture of toluene and dimethylformamide. When we reproduce these tests, the yields obtained in ditertiobutyl carbonate are not sufficient.

 The present invention has made it possible to prepare di-tert-butyl carbonate directly from diacid dichloride or the like in good yields.

 It consists in condensing tert-butyl pyrocarbonate with diacid dihalide or equivalent in the presence of at least one complexing agent.

avec X représentant un groupe partant, avantageusement choisi parmi les acyloxyles, et les halogénures de préférence chlorure et bromure avec R1, R2, R3 étant aryle ou de préférence alcoyle (selon la définition du dictionnaire de chimie DUVAL) ou hydrogène, R1, R2, R3 ne pouvant être simultanément hydrogène ;R1, R2, R3 étant avantageusement tels qu'un seul d'entre eux, de préférence aucun, ne soit hydrogène ; avec n représentant un entier choisi entre un et deux ; avec M représentant un métal alcalin de faible rayon atomique avantageusement le lithium et le sodium ; avec la condition que lorsque ledit dihalogénure de diacide est le phosgène, le diphosgène, triphosgène, et que l'agent complexant est une mono amine tertiaire, une amine choisie parmi le 1,4-diazabicyclo (2,2,2) octane, 1,8-diazabicyclo (5,4,0), undecene-7, hexamethyltetramine,
N-methylpiperidine, N-ethylpiperidine, N-methyl, l'alcalin est le lithium et de préférence le sodium La somme des carbones de R'1, R'2 et R'3 étant avantageusement au plus égale à 25, de préférence à 12.The reaction can be schematized as follows

with X representing a leaving group, advantageously chosen from acyloxyls, and the halides preferably chloride and bromide with R1, R2, R3 being aryl or preferably alkyl (according to the definition of the DUVAL chemistry dictionary) or hydrogen, R1, R2, R3 can not be hydrogen simultaneously, R1, R2, R3 being advantageously such that only one of them, preferably none, is hydrogen; with n representing an integer selected from one to two; with M representing an alkali metal of small atomic radius, advantageously lithium and sodium; with the proviso that when said diacid dihalide is phosgene, diphosgene, triphosgene, and the complexing agent is a tertiary monoamine, an amine selected from 1,4-diazabicyclo (2,2,2) octane, 8-diazabicyclo (5,4,0), undecene-7, hexamethyltetramine,
N-methylpiperidine, N-ethylpiperidine, N-methyl, the alkali is lithium and preferably sodium. The sum of the carbons of R'1, R'2 and R'3 is advantageously at most equal to 25, preferably 12.

Advantageously X is chosen so that R2 (R1) (R3) C-O-COOH has a pKa greater than that of HX, preferably of a value at least equal to 2.

The preferred HX has a pKa of at most 2 and is most often halohydric, advantageously hydrobromic or especially hydrochloric, in which M represents an alkali metal.

 The tert-butyl pyrocarbonate is obtained in a manner known per se, for example by carbonation of tert-butylate.

 Among the tert-butyl pyrocarbonates, it is preferred to use the alkaline salts and, more particularly, the sodium salt (M = Na).

The sequestering agents which can be used are advantageously chosen firstly from amines and secondly from ethers whose molecules comprise at least one other ether function.

 Thus, the sequestering agents which can be used are advantageously chosen so that they comprise, or at least one amine function; or else an ether function and at least one amine and / or ether functional group to form a complexing agent advantageously at least bidentate, preferably tridentate, the ether and / or amine functions being separated by at least 1, advantageously 2 atoms and by at most 4 preferably at most 3 atoms, usually carbon.

When the known coordination atoms are interconnected by 2 branches thus forming a cycle, it is preferable that at least one branch has at least 3 members and the other at least 2.

The usable amine functions should not be susceptible to react with phosgene, oxalyl halides or the like, and are preferably tertiary
The complexing molecules advantageously have from 3 to 75 carbon atoms, preferably from 6 to 39 carbon atoms.

The size and mobility must be such that bi, tri or polydentés are complexing. This is not the case for 1,4 diaza (2,2,2) bicyclo octane; which explains the poor result obtained (example B).

 In general, this constraint can be quantified by indicating that the bicyclic systems having a number of members at most equal to 8, especially when the bridgeheads are the coordination atoms, of the diaza-bicyclooctane-, heptane type. and inferior and to a lesser extent nonane are to be avoided. In a more general manner, it is advantageous to avoid any bicyclic system whose bridgeheads are atoms intended to ensure coordination and of which 2 of the branches have, apart from the bridgeheads, a length of links at most equal to 2, preferably not more than 3 when the third branch has a length, expressed as a link, of less than 7.

 The at least one bidentate character with preferably at least one amine function is necessary for the phosgene and derivatives, but not for the oxalyl halide and the like.

 At least 3 classes of complexing agents, including oxygenated tertiary amines, may be mentioned as particularly advantageous; oxygenated polyethers or sulfur, cyclic or macrocyclic; the cryptands.

The first class consists of sequestering agents of general formula
N - E - CHR1 - CHR2 - O - (CHR3 - CHR4 - O) n - R5] 3 (I) wherein n is an integer greater than or equal to 0 and less than or equal to about 10 (O $ n) ), R1, R2, R3, R4, which are identical or different, represent a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms and Rs represents an alkyl or cycloalkyl radical having from 1 to 12 carbon atoms, a phenyl radical; or a radical of formula -CmH2m-C6H5, or CmH2m + 1-C6H5, m being between 1 and about 12.

 The second class of complexing agents consists of cyclic polyethers, preferably macrocyclic, having from 6 to 30 atoms in the ring and preferably from 15 to 30 atoms in the ring and consisting of from 2 to 10, preferably from 4 to 10 units. Wherein X is either -CHR6-CHR7- or -CHR6-CHR8-CR9R7, wherein R6, R7, R8 and R8 are the same or different and are a hydrogen atom or an alkyl radical having 1 to 4 carbon atoms; X may be -CHR6-CHR8-CR9R7- when -OX- units include -O-CHR6-CHR7.

dans lesquelles
- Y représente 0, N ou P
- A représente un groupement alkylène ayant de 1 à 3 atomes de carbone.The third class of complexing agents consists of the compounds of general formula
RI-YA-D] p A-Y-R10 IIa

in which
Y represents 0, N or P
- A represents an alkylene group having 1 to 3 carbon atoms.

 - D represents 0, S or N-R1l where R11 represents an alkyl radical having 1 to 6 carbon atoms.

 - R1o may represent an alkyl radical having 1 to 6 carbon atoms, p, q and r identical or different are integers between 1 and 5.

According to a preferred embodiment of the process of the invention, at least one sequestering agent of formula (I) in which R1,
R2, R3 and R4 represent a hydrogen atom or a methyl radical, Rs and n having the above meaning.

Among these, it is even more particularly preferred to use the sequestering agents for which n is greater than or equal to 0 and less than or equal to 6, and for which Rs represents an alkyl radical having from 1 to 4 carbon atoms.

We can cite
tris (oxa-3-butyl) amine of formula
N- (CH2-CH2-O-CH3) 3
tris (3-oxaheptyl) amine of formula N- (CH 2 -CH 2 -O-C 4 H 9) 3
tris (3,6-dioxaheptyl) amine of formula N- (CH2-CH2-O-CH2-CH2-O-CH3) 3
tris (trioxa-3,6,9 decyl) amine of formula
N- (CH2-CH2-O-CH2-CH2-O-CH2-CH2-O-CH3) 3
tris (3,6-dioxa-octyl) amine of formula N- (CH2-CH2-O-CH2-CH2-O-C2Hs) 3
tris (trioxa-3,6,9 undecyl) amine of formula N- (CH2-CH2-O-CH2-CH2-O-CH2-CH2-O-C2H5) 3
tris (3,6-dioxo nonyl) amine of formula N- (CH 2 -CH 2 -O-CH 2 -CH 2 -O-C 3 H 7) 3
tris (trioxa-3,6,9 dodecyl) amine of formula
N- (CH2-CH2-O-CH2-CH2-O-CH2-CH2-O-C3H7) 3
tris (3,6-dioxa decyl) amine of formula N- (CH 2 -CH 2 -O-CH 2 -CH 2 -O-C 4 H 9) 3
tris (trioxa-3,6,9 tridecyl amine of formula N- (CH2-CH2-O-CH2-CH2-O-CH2-CH2-O-C4Hg) 3
tris (tetraoxa-3,6,9, 12 tridecyl) amine of formula
N- (CH2-CH2-O- (CH2-CH2-O) 3-CH3) 3
tris (3,6-dioxa-4-dimethylheptyl) amine of formula N- (CH2-CH2-O-CHCH3-CH2-O-CH3) 3
tris (3,6-dioxa-2,4-dimethylheptyl) amine of formula
N- (CH2-CHCH3-O-CHCH3-CH2-O-CH3) 3.

 It is preferred to use, among the compounds of formula (I): tris (dioxaheptyl) amine (or TDA1).

The preparation of these sequestering agents is described in the application for
French Patent 79 05438 published under No. 2450120.

 The cyclic ethers which can be used in the process according to the invention include compounds such as dioxane or macrocyclic ethers known under the general name of "crown ethers" which are described in French Patent 69. 43879 published under number 2.026.481.

Examples of crown ethers which may be used according to the invention

Part of the compounds of the third class of complexing agents are described in French Patent 70.21079 published under number 2.052.947.

Examples of compounds of this class which are suitable for carrying out the process according to the invention may be mentioned.
CH3-O-CH2-CH2-O-CH2-CH2-OCH3

 According to a first preferred method of implementation of the invention, the sodium tertiobutylate is brought into contact with carbon dioxide, then phosgene or diphosgene or tri phosgene is added.

 The complexing agent can be introduced at any time, before carbonation or before the introduction of phosgene or diphosgene or tri phosgene.

 According to a second preferred method, phosgene or diphosgene or triphosgene is first introduced, then t-butyl pyrocarbonate is added, the complexing agent can be added at any time.

The reaction can be carried out in any solvent whatever the nucleophilicity of the medium. Among the solvents
aromatic hydrocarbon derivatives such as
. benzene,
. xylenes,
. toluene,
oxygenated solvents such as dioxane and ethers
dimethyl ethylene glycol or polyethylene glycols and
their mixture which solvents can act as complexing (s).

 According to a preferred embodiment of the invention is used a molar amount of dihalide or diacid or equivalent between 0.3 and 1 time, the amount of tert-butylate used.

 The reaction temperature is advantageously between -10 C and 60 ° C.

 The present invention will be more fully illustrated by the following examples which should not be considered as limiting the invention.

Examples 1 and 2 and Comparative Test A
Typical procedure. Influence of the amount of TDAI
In a 250 ml reactor, it is charged
12.8 g of tert-butyl sodium (0.075 mole)
150 ml of dry toluene.

At room temperature, CO2 is introduced, which causes a
exotherm. The introduction is done in thirty minutes.

The introduction of the CO 2 is then stopped and the reaction mixture is cooled to 15 ° C., at which temperature the TDA1 is firstly added and then phosgene at 2 H 30. The reaction mixture is very thick. It is then allowed to rise to 35 ° C. and the mixture is stirred for 2 hours 30 minutes, then possibly another hour at 55 ° C.

After cooling, 100 ml of ice water are added. The organic phase washed with 3 x 100 ml of water, dried over 15 g of sodium sulfate is evaporated at room temperature. The obtained product of orange color is analyzed by GPC.

<Tb>

<SEP> Time <SEP> I <SEP> I <SEP> I
<tb><SEP> Time <SEP> Time <SEP> Time <SEP> Quantity <SEP> TDA1
<tb> TEST <SEP> of introduction <SEP> to <SEP> to <SEP> phosgene <SEP> (m1) <SEP> RR <SEP>%
<tb><SEP> of <SEP> phosgene <SEP> 35 C <SEP> 55 C <SEP> (moles)
<tb> Comparative <SEP> A <SEP> 2 <SEP> h <SEP> 30 <SEP> 2 <SEP> h <SEP> 30 <SEP> 1 <SEP> h <SEP> 0, <SEQ> 102 <SEP> 0 <SEP> 31
<tb> Example <SEP> 1 <SEP> 2 <SEP> h <SEP> 30 <SEP> 2 <SEP> h <SEP> 30 <SEP> 1h <SEP> 0.078 <SEP> 3 <SEP> 58
<tb> Example <SEP> 2 <SEP> 2 <SEP> h <SEP> 30 <SEP> 2 <SEP> h <SEP> 30 <SEP> 0 <SEP> 0.097 <SEP> 3 <SEP> 41
<Tb>
RR is understood to mean the yield on the product introduced, that is to say
amount of product obtained (moles)
---------------------------------%
amount of tertiobutylate introduced (moles)
Example 3
Influence of temperature
We operate as in Example 1 by charging
0.075 mole of sodium tert-butylate
0.112 moles of phosgene
150 ml of toluene
3 ml of TDA 1 (0.0015 mole) Carbonation is carried out at 10 C,
then the reaction temperature is brought to 55 ° C and this
temperature, phosgene is introduced for 2 hours 30 minutes; then the
The reaction is continued at this temperature for 3 hours.

 An RR of ditertiobutyl dicarbonate of 66% is obtained.

Example 4
Use of triphosgene
We operate as in Example 1 by charging
0.13 moles of sodium tert-butylate (TBuONa)
0.0167 moles of triphosgene (ie 0.0501 moles of phosgene)
75 ml of toluene
0.015 mole of TDA 1
The carbonation is carried out at 10 ° C. and after introduction of the triphosgene, the reaction is continued at 20 ° C. for 5 h 30 min.

 An RR in BOC2O of 51% is obtained (in this example the RR is calculated relative to the engaged trinhospene expressed in phosgene).

Example 5
Use of diphosgene
We operate as in Example 1 by charging
0.13 moles of sodium tert-butylate (TBuONa)
0.025 moles of diphosgene (ie 0.0500 moles of phosgene)
75 ml of toluene
0.015 mole of TDA1
The carbonation is continued at 20 C for 5 h 30.

 An RR in BOC20 of 50% is obtained (in this example, the RR is calculated with respect to the engaged diphosgene expressed in phosgene).

Example 6
In a 250 ml reactor, 12.8 g of tBuONa (0.13 mole) are charged, and toluene and C are bubbled for 30 minutes in order to form tertiary butyl pyrocarbonate after stopping the reaction. introduction of CO2, 5 9 TDA1 is added. 6.6 g of oxalyl chloride (0.051 mol) are cast at 5 ° C. in 15 minutes, the temperature is allowed to rise and the mixture is left to stir for 4 h 30. After treatment, 7.6 g of a solution are collected. in which, by GPC, 79% of BOC2O is determined, which represents a yield of 54% relative to the oxalyl chloride employed.

Example 7
Synthesis of BOC20 from oxalyl chloride in the presence of diisopropyl ethyl amine
In a 250 ml reactor, 75 ml of toluene, 12.8 g of t.BuONa (130 mM), 3 ml of diisopropylethylamine are charged. To this slurry, CO 2 is added at room temperature for about 30 minutes until the CO 2 output rate is the same as the inlet flow rate.

After cooling to 5 ° C., 6.4 g of oxalyl chloride (42.8 mM) in solution in 30 ml of toluene are added over 20 minutes and the mixture is then allowed to return to room temperature, where it is stirred for 5h.

After treatment, 5.05 g of a liquid in which
30% NMR BOC20, representing a yield of 10% relative to the oxalyl chloride engaged.

Example B Comparative
Phosgenation in toluene in the presence of 1,4-diazabicyclo (2,2,2) octane
In a 250 ml reactor, 7.5 g of tBuONa (75 mM), 1.7 g of 1,4-diaza-bicyclo (2,2,2) octane (15 mM) and 75 ml of toluene are charged. At this suspension, CO 2 is introduced at ambient temperature for about 30 minutes, until the flow rate of CO2 at the outlet is identical to the flow rate at the inlet.

At room temperature, 11.9 g of phosgene (120 mM) are introduced during 2 hours and then purged with nitrogen while heating the reaction mixture at 55 ° C. for 2 hours.

After cooling and treatment, 9.5 g of a white liquid are collected in which 4.6% BOC 2 O is dosed, which corresponds to a yield of 1% relative to sodium t-butoxide.

Comparative Example C
In a 250 ml reactor, 12.8 g of tBuONa (0.13 mole) are charged, and toluene and 5 ° C are bubbled for 30 minutes with CO 2 to form tert-butyl pyrocarbonate 6.6. g of oxalyl chloride (0.051 mol) are cast at 5 ° C. in 15 minutes, the temperature is allowed to rise and then the mixture is stirred for 4 h 30. After treatment, 13.9 g of a solution are collected in which by GPC, 2.6% BOC20, which represents a yield of 3.2% relative to the oxalyl chloride employed.

Claims (9)

A process for the preparation of alkyl dicarbonate, characterized in that an alkyl or aralkyl alkali pyrocarbonate and a diacid dihalide in the presence of a complexing agent are contacted with the proviso that when said diacid dihalide is phosgene, diphosgene, triphosgene, and the complexing agent is a tertiary monoamine, an amine such as 1,4-diazabicyclo (2,2,2) octane, 1,8-diazabicyclo [5] , 4.0), undecene-7, hexamethyltetramine, N-methylpiperidine, N-ethylpiperidine, N-methyl, the alkaline is lithium and preferably sodium. 2. Method according to claim 1, characterized in that the tertiobutyl pyrocarbonate is a sodium salt. 3. Process according to claim 1, characterized in that the reaction is carried out in an aromatic solvent, preferably in toluene. 4. Process according to claim 1, characterized in that the complexing agent is chosen from oxygenated tertiary amines in particular having an ether function; oxygenated polyethers or sulfur, cyclic or macrocyclic; the cryptands. 5. Process according to claim 4, characterized in that the oxygenated tertiary amines correspond to the formula N - [- CHR1 - CHR2 - O - (CHR3 - CHR4 - o-) n -R5] 3 wherein n is an integer greater than or equal to 0 and less than or equal to about 10 (O 4 n 410), R1 R 2, R 3, R 4, which may be identical or different, represent a hydrogen atom or an alkyl radical having from 1 to 4 carbon atoms and R 5 represents an alkyl or cycloalkyl radical having from 1 to 12 carbon atoms, a phenyl radical or a radical; of formula -CmH2-O, or CmH2m + 1-O, m being between 1 and about 12. 6. Process according to claim 4, characterized in that the complexing agents correspond to the following formulas II

 in which  Y represents 0, N or P  - A represents an alkylene group having 1 to 3 carbon atoms.  - D represents 0, S or N-R11 represents an alkyl radical having 1 to 6 carbon atoms.  - R1o may represent an alkyl radical having 1 to 6 carbon atoms, p, q and r identical or different are integers between 1 and 5. 7. Process according to claim 5, characterized in that the oxygenated amine is tri (oxaheptylamine). 8. Process according to claims 4 and 6, characterized in that the polyether is the diethylene glycol methylether. 9. The method of claim 4 characterized in that the polyether is dioxane.