DE2009928A1 - Process for the production of organic compounds - Google Patents

Description

Process for the production of organic compounds

The invention relates to the production of organic compounds, in particular to the production of Carboxylic acids, lactones and alcohols.

The invention consists in having an organic Halogen compound or an epoxy with an olefinic compound in the presence of a metal in a reduced state, the to carry out one-electron oxidation-reduction reactions suitable, brings in touch. The course of the process using an organic halogen compound can be shown schematically as follows:

> C = C <+ XCR ¹ R ^{1 1} Y

»Vc = CCR ¹ R ¹¹ Y and / or

! ι.
- C - C - CR ¹ R ^{1 1} Y

0 09837/2 282

wherein R ¹ R ' ^{1 represent} substituent groups or hydrogen, X is halogen and Y represents a substituent group or hydrogen.

If the unsaturated derivative / C = C-CR ¹ R ¹¹ Y is produced, the reaction proceeds catalytically and there is no overall change in the valence state of the metal. Simultaneously with the generation of the saturated derivative, however, the metal is oxidized to a higher valence state with consequent termination of the reaction. Therefore, when the saturated and unsaturated products are obtained together, the production of both eventually ceases as the formation of the saturated form consumes the reduced form of the metal.

Preferred organic halogen compounds are those with chlorine or bromine. In the process, chlorinated paraffins, in particular chlorinated paraffins with up to 20 carbon atoms in the molecule, and chlorinated aromatic substances such as chlorobenzene, can be used, in these two cases Y in the above equation represents carbon and hydrogen or hydrogen and in the latter case CR ¹ R ¹¹ forms an aromatic ring. However, the method is particularly applicable to organic halogen compounds which contain other substituents, in particular those substituents such as -OH, -CIIO, -CONH ₂ , -COOH, -ClI, -COR and -COOR, where R is an alkyl or aryl group, in particular represents a C to C _g alkyl group or a phenyl group.

. 7t p

Substituted aliphatic halogen compounds are preferred for use in the process, especially those containing up to 20 carbon atoms. Halogen-containing substituted paraffinic compounds are preferred aliphatic compounds, it being possible for the halogen and the substituent groups to be in any position along the carbon chain. In particular, the paraffinic compound has the structure X (CII ₀ ) Y, wherein - as above - X is a halogen and γ is a substituent group and η is an integer, suitably 1 to Io #. Examples of suitable organic halogen compounds are chlorohydrins, such as ethylene and propylene chlorohydrin, chloro- and bromoacetic acids and their esters, nitriles and amides.

When the organic halogen compound is a carboxylic acid or a derivative such as an ester will be common a third type of product, namely a lactone:

= C <"+ XCR ¹ R ¹¹ COOR *) C - C -CR ¹ R ¹¹

0 CO

Similar to the production of unsaturated esters, lactone formation takes place without oxidation of the metal.

If an epoxy is used as a reaction component in the process is present, the course of the reaction is as follows :,

009837/2282 Λ

Λ KII \ C = C <+> C- C {> - (C - CJ- C - C - OH

i.e. the product is an alcohol.

In this case the product as a whole is essentially saturated, as a result of which the metal is oxidized.

Preferred are the Epoxyce Olefinoxyde, in particular with up to Olefinoxyde Io carbon atoms, such as ethylene oxide, \ propylene oxide and butylene oxide. The styrene-derived epoxy can also be used.

The at. The olefinic compound used as a reactant in the process is preferably an olefinic one Hydrocarbon of a straight or branched chain and in particular can contain up to <£ G carbon atoms. Alpha olefins are particularly suitable olefinic hydrocarbons, for example alpha-olefins with up to 20 carbon atoms in the Molecule, such as hexene-1, octene-1, dodecene-1 and tetradecene-1.

The lower alpha-olefins are preferred reaction components, particularly ethylene and propylene, which are a Teloraerisationsreaktion can enter, with the ethylene or propylene polymerized with the overall effect of forming a product, such as from a higher molecular weight olefin, viz

Ii ii

of the structure (CC) CR ¹ R ' ¹ Y and / or H (C - C) CR ¹ R ¹¹ Y or

ι I I I '' lim

H (C-C) _m C-C OH, where m is an integer. So can

¹ '' 009837/2282 ^:

e.g. ethylene to produce a product (CH ^ CH-)

, CR ¹ R ¹¹ Y and / or H (CH ₀ CH ₀ ) CR ¹ R ¹¹ Y or H (CH ₀ CH ₀ ) CC OH rea-

z 2. m ί ί m ι ι

yaw. When the lower alpha olefins are used as reaction components are used, both the pressure of the olefin and the reaction temperature are important factors in the determination the chain length of the products obtained. In general, increasing olefin pressure or partial pressure increases the chain length of the Products. Olefin prints up to looo at can be used however, prints are ", -from 5 to 500 at, especially 5 to loo at, - and especially Io to 50 at is preferred. Under these circumstances if the product contains a mixture of chain lengths with a distribution around a mean value, and the mean value increases with increasing Olefin pressure. The preferred maximum temperature for this embodiment of the invention is 200 ° C, with 75 ° to 150 ° C is a preferred range. above 2oo C. some degradation of the product takes place and there is a tendency to produce an increased amount of branched chain By-products. . :.

• Although branched-chain lower olefins such as propylene or the butenes can be used, ethylene is preferred, since a straight-chain product is obtained, and straight-chain Alcohols and esters together are important in detergent manufacture and in the production of plasticizer esters for polyvinyl chloride. Ethylene oxide is likewise before propylene or Butylene oxides preferred. It can be omega-haloalkaric acids or their derivatives instead of chloroacetic or bromoacetic acid or their esters can be used. However, because the latter is easier

009837/2282

are available, they are preferred. In general, the most valuable products are grounded from the lower alpha olefins obtained when m is in the product forms given above in the range from 1 to 12, preferably 1 to 8, is.

A one-electron oxidation-reduction reaction is a reaction in which there is a transfer of an electron to the or from the metal. In order to be able to enter into such a transfer, the metal must therefore be suitable for in two adjacent valency states occur. Metals suitable for this purpose are iron, copper, titanium, vanadium and Uranium, preferably chromium. The metal can be used as such, but is generally used as a salt or complex, e.g. as a halide, for example a chloride such as vanadium chloride, as an alkanoate, for example an alkanoate with up to to 20 carbon atoms, v / ie titanium stearate or vanadium acetate, or as carbonyl, e.g. Chromium carbonyl applied. Also can Mixtures of metals or mixtures of compounds of different metals, e.g. a mixture of a chromium compound and a vanadium compound can be used in the method of the invention. Generally speaking, catalytic amounts are Metal for use in the process, for example

-4
1 χ Io to 1 molar, preferred.

The process can be carried out in the presence or absence of an inert diluent, a polar diluent Liquid is generally preferred. Such diluents include alcohols, e.g., ethanol, propanol and the butanols;

009837/2282

lower alkanoic acids such as acetic acid; Acid derivatives, e.g. Amides, such as dimethylformamide, N-methylaeetamide, dimethylacetate - amide; Nitriles such as acetonitrile, propionitrile and behzonitrile; · Esters, especially of the lower alkanoic acids, e.g. methyl acetate, Benzyl acetate, ethylene glycol diacetate, methyl propionate and ethyl butyrate; Ketones such as acetone, methyl ethyl ketone and cyclohexanone; Esters such as 1,2-dimethoxyethane and tetrahydrofuran; and various organic polar liquids, such as dirnethyisulfoxide, Diphenyl sulfoxide and sulfolane are possible. Water can also be used as a diluent.

Although the process is preferably as a homogeneous liquid phase reaction is carried out, it can also be carried out heterogeneously in the liquid or gas phase. So can the metal or the metal compound in the liquid phase either alone or on an inert carrier, e.g. silicon dioxide, pumice stone, asbestos, liagnesium oxide-aluminum oxide or carbon, suspended will. A gaseous olefin and olefin oxide can also be used or acid or acid derivative in the vapor phase via the metal or the metal compound on a support or without Carriers are directed. The latter response can be used for convenience are used in the manufacture of the products which are volatile at the reaction temperature and which .therefore can be easily removed from the reaction zone.

The method can be carried out by the incorporation of a metal sequestering agent (Complexing agent) or a ligand in the reaction medium can be improved. When a sequestering agent

009837/2282

(also masking agent) is used, it is preferably in a molar concentration in the range of 3 to 10 times the molar concentration of the metal present. Suitable sequestering agents are ethylenediamine and ethylenediaminetetraacetic acid and the ethanolamines. Suitable ligands which can be used in a concentration similar to that of the sequestering agents, are / imines, e.g. the ethylamines, phosphines, e.g. triphenylphosphines and arsines, e.g., diphenylethylarsine. The sequestering agents and ligands are useful because they complex with the metal ion and do not change valence of the metal facilitate the transformation of the metal into its next valence state.

As described above, the production of saturated derivatives leads to the consumption of the catalyst, so that it it is often advantageous to provide a reducing agent to convert the metal back into the reduced state. Such Kecuktionsiuittel can be in situ or in a separate Level can be applied. Suitable reducing agents are 2ink and acid and hydrazine. Reductive regeneration can also be carried out electrolytically.

In general, the process can be carried out over a wide temperature range, for example from -5o ° up to 3oo C, preferably ο to 2oo ° C.

The products of the process contain long-chain alcohols

and acids and acid derivatives, which are valuable chemical

f) 098 3 7 /? 282

ORIGINAL

Represent intermediates.

Butyrolactone, which can be obtained from ethylene and an acid or an ester at low ethylene pressures, is also a valuable chemical intermediate for the production of N-methylpyrrolidone.

The invention is illustrated in more detail by the following examples. ·

example 1

2oo ml of aqueous dimethylformamide containing 1.6 χ

-2
10 mol of chromium-tl) chloride and 2.0 ml of ethylenediamine were added over the course of one hour under a nitrogen atmosphere to a mixture of 20 ml of 1-octene and 1.0 ml of ethyl bromoacetate. During the addition, the solution was quickly stirred at 20C. After the addition was complete, the solution was stirred for 1 hour and then poured into a large amount of water. The reaction products were extracted into ether, the extract washed repeatedly with water, dried over anhydrous magnesium sulfate and concentrated to a small volume. The concentrate was examined by gas liquid chromatography and found to contain 0.5 10 ~ moles of ethyl decanoate and a trace of gamma-decane lactone. The products were isolated by elution from a liquid chromatography column.

009837/2282

- Io -

Example 2

Example 1 was repeated with the exception that the Chromium (II) chloride solution to a mixture of 2o ml octene-1 and Io ml of ethyl bromoacetate was added. During the reaction, 0.26 x Io moles of ethyl n-decanoate and 0.28 χ Io hol gamma-decane lactone manufactured.

Example 3

Example 1 was repeated with the exception that the chromium (II) solution was added to 2o ml octene-1 and 2o ml ethyl bromoacetate was admitted. The yields of ethyl n-decanoate and gamma

—2 —2

Decane lactone was 0.32 Io mol and 0.58 χ Io, respectively

Mol. Some ethyl dec-4-enoate (0.8 lo ^-3 mol) was also discovered in the product.

Example 4

Example 1 was repeated again, with the chromium (II) solution was added to a stirred mixture of 20 ml octene-1 and 10 ml ethyl chloroacetate at 7o C. The reaction products were ο, 13 χ Io moles of ethyl decanoate and traces of gamma decane lactone.

009837/2282

Example 5

- 2

ο, 3 χ Io mol vanadium (II) chloride in dimethylformamide, Containing about 20% water (100 ml), are added drop by drop under a nitrogen atmosphere to a mixture "" of 20 ml octene-1, 10 ml ftthylchloracetet und.So ml dimethylformamide, stirred at 70 ° G admitted. After the reaction products had been worked up, ο, Ι lo ~ hol ethyl decanoate and o.65 χ lo ~ moles of gamma-decane lactone were obtained won. ■

Example 6

Example 5 was repeated with the exception that one Vanadium II solution to form a mixture stirred at 40 ° C 20 ml of 1-octene and 10 ml of iithyl bromoacetate were added. at the reaction were o, 15 χ Io moles of ethyl decanoate and o, 5 χ

-4
Io Mol gamma decaniactone made.

Example 7

-2

A solution of 0.5 χ Io mol of titanium (III) sulfate and

0.2 ml of ethylenedianine in 150 ml of dimethylformamide was added dropwise to a mixture of 20 ml of 1-octene and 10 ml of ethyl chloroacetate in 50 ml of dimethylformamide with stirring at 70 ° C., after which 0 ₁ 1 χ mol Ethyl decanoate and one

Trace of gamma decaniactone found in the products.

0098 37/228

Example 8

It was a chromium (II) solution as in Example 1 with except that ethylenediamine was omitted. This solution became a mixture over the course of an hour from 2o ml of 1-octene and 10 ml of ethyl bromoacetate at 2o C. are added.

-2 · -3

There were o, 23 χ Io mol of ethyl decanoate and ο, 26 χ Io mol gamma-decane lactone produced in the reaction.

Example 9

_2

1.6 χ Io mol of chromium (II) chloride in loo ml of dimethylformamide, containing 2 ml ethyl diamine, were in the course of half an hour to a solution of Io ml ethyl bromoacetate, the cooled to -2o ° C and saturated with ethylene was given. The reaction was carried out under an atmosphere of ethylene. That The system was finally allowed to warm up to room temperature, and the products were obtained as described in Example 1

-2 ben. In the products were o, 1 χ Io moles of ethyl n-butyrate and found a trace of gammarbutyrolactone.

Example Io

Example 8 was made using ethyl alcohol as the Solvent instead of an aqueous dimethylformamide repeated. The yield of ethyl decanoate was o, ll χ Io mol and

_ 2

the yield of gamma-decane lactone o.33 χ Io mol.

009837/2282 ^:

Example 11

-2
A solution of 1.6 χ Io Hol vanadium (II) chloride

in 15o ml of aqueous dimethylformamide was in the course of a , Hour to a mixture of Io ml of 3-chloropropan-l-ol and 2o ml of Hepten-1 were added under an argon atmosphere at 70 ° C. The system was left to stand at 7ο C for an additional hour, and then the products were isolated by ether extraction as described in Example 1. In the reaction 12 χ Io mol n-decanol "were obtained.

Example 12

Example 21 was made by replacing the vanadium chloride

_2

by chromium (II) chloride (1.6 χ Io mol) and ethylenediamine (2, ο ml) repeated. The yield of n-decanol was 0.14

—2
χ Io Mol.

Example 13

τ r "-i""" ^{2 Mo1} chromium (II) chloride and 2 ml ethylenedi-

X, υ Χ XO

amine in 40 ml of dimethylformamide and 80 ml of ethanol were in the course of one hour in a nitrogen atmosphere to a mixture of 20 ml of 1-octene and 1 ml of ethylene chlorohydriri, stirred at 70 ° C. admitted. The product was isolated by ether extraction as described in Example 1. As a product, n-decanol was found. '

009837/2282.

Example 14

Example 13 was repeated with the exception that the ethylene chlorohydrin was replaced by 1 ml of ethylene bromohydrin v / urde. The reaction was carried out at 20 ° C and was found to be a product of n-decanol.

Example 15

_2

1.6 χ Io moles of chromium (II) chloride in 100 ml of water

became a vigorously stirred mixture of 10 ml of ethyl bromoacetate and 20 ml of 1-octene in the course of half an hour given. The reaction was carried out at 25 ° C under an argon atmosphere. The organic phase was then separated off, diluted with ether and dried over anhydrous magnesium sulfate. The ether was evaporated and it was found by gas-liquid chromatographic analysis that the Containing residue ethyl decanoate and gamma-decanolactone.

Example 16

1.6 χ Io mol of chromium (II) chloride in 2oo ml of dimethylformamide, containing 2 ml of ethylenediamine, became a mixture of 1 ml of chloroacetonitrile and. ' Given 2o ml octene-1. The product was worked up by ether extraction as in Example! And it was found that it contained n-nonyl cyanide.

009% 37 / -22

Example 17

5 moles of dimethylformamide, ο, 15 moles of ethylenediamine .und 1 ml of ethylene oxide was placed in a stainless steel autoclave heated at 12o ° C under an ethylene pressure of 24.5 at. It became an anhydrous solution of 0.05 moles of chromium (II) chloride in 5 moles of dimethylformamide over the course of 2 hours Reactor fed. The solution was treated with water and the product extracted with ether. The alcohol yields (based on added Cr (II) -SaIz) were measured as acetates Gas-liquid chromatography determined as follows: Ethyl alcohol: 4.8%, n-butyl alcohol: 3.9%, n-IIexyl alcohol: 2.4 S, n-octyl alcohol hol: 1.7%, n-decyl alcohol: 1.2 S.

Example 18

Example 17 was repeated with the exception that no ethylenediamine was added. The yield of alcohols was: ethyl alcohol: 3.8 pounds, n - butyl alcohol: 2.1%, n-hexyl alcohol: 1.6%, n-octyl alcohol: o, 8v and n-decyl alcohol: o, 23.

Example 19

Example 17 was repeated with the exception that o, o5 Jlol hydrogenated chromium (II) chloride was used. the Yields of alcohols were: ethyl alcohol: 4.55, n-butyl alcohol: 3.2ν, n-Ke: iyl alcohol: 1.9%, n-octyl alcohol: I, o5, n-decyl alcohol: ο, 45ί.

009837/228 2

BATH

Example 2o

Example 19 was repeated while increasing the ethylene pressure to 34 atm. The yield of alcohols was: Ethyl alcohol: 3,3S, n-sutyl alcohol: 6.15, n-hexyl alcohol: 2.5%, n-octyl alcohol: 1.12, n-decyl alcohol: 0.6%, i.e. the higher pressure led to an increased yield of longer-chain products.

Example 21

0.18 moles of ethyl bromoacetate and 3.5 moles of dimethylformamide were heated to 12o ° C under an ethylene pressure of 29.2 at. A solution of 0.05 moles of hydrogenated chromium (II) chloride was obtained fed in 5 moles of dimethylformamide to an autoclave in the course of 2 hours. It was found by analysis that the resulting solution 12.9% ethyl acetate, 14.5% ethyl n-butyrate, 12.1% ethyl n-hexanoate, 4.3% ethyl 2-ethylhexanoate, 10.2% Containing ethyl n-octanoate and 3.9% ethyl n-decanoate, wherein all yields are based on added chromium (II) salt.

Example 22

Example 21 was repeated at 100 ° C. and an ethylene pressure of 32.3 atm. The yields of ethyl esters were: 7.3% ethyl n-hexanoate, 1.2% ethyl 2-ethylhexanoate, 3.3% ethyl n-octanoate, 2.5% ethyl n-decanoate.

009837/2282

Example 23

2oo ml of aqueous dimethylformamide containing 1.6 χ Io moles of chromium (II) chloride and 2, ο ml of ethylenediamine, were added over the course of one hour under a nitrogen atmosphere to a mixture of 20 ml octene-1 and 19 ml bromobenzene. While The addition of the solution was stirred rapidly at 20 ° C. After the addition was completed, the solution became one hour stirred and then poured into a large amount of water. The reaction products were extracted into ether, the extract was washed repeatedly with water, dried over anhydrous magnesium sulfate, and concentrated to a small volume. The concentrate was examined by gas-liquid chromatography and found to be a considerable amount contained n-octylbenzene.

Example 24

Example 23 was carried out with the replacement of the bromobenzene

■ 19 ml of p-bromoanisole repeated. Analysis of the product showed

the presence of p-n-octylanisole.

Example 25

loo ml of dimethylformamide, containing 1.6 χ Io mol Vanadium trichloride, were added over the course of 1 1/2 hours a mixture of 10 g of chloroacetic acid, 2o ml of 1-octene and 50 ml of dimethylformamide were added at 70 ° C. The product was

0 0 9 8 ^ 7/2 2 8 2

isolated by the procedure used in Example 2j,

ORIGINAL INSPECTED

- 13 -

and it was found to be ethyl decanoate and gamma-decane lactone contained.

Example 26

-2

15o Dl dimethylformamide, containing 1.6 χ Io mol

Chromium (II) chloride, were added to Io ml over the course of an hour Ethyl bromoacetate and 10 ml of octene-1 at ambient temperature admitted. The products were extracted with petroleum ether in the ratio 100/12 and the extract was found to be Ethyl decanoate in a 3.7 igen yield, based on chromium, contained.

3 ml of concentrated hydrochloric acid was added to the dimethylformamide solution added after extraction and the solution drained down a zinc amalgan column. the Chromium (II) solution emerging from the column was added to a mixture of 2o ml ethyl bromoacetate and 2o ml octene-1, a lo, 2% yield of ethyl decanoate, based on chromium, was obtained.

The diraethylformamide solution of chromium (III) was like previously reduced and reused, resulting in a 11.4% yield of ethyl decanoate, based on chromium. The chrome solution was thus 3 cycles with a certain reduction in activity subject.

009837/2282

Example 27

A mixture of 3o ml octene-1, 25 ml ethyl bromoacetate, 2.2 g of chromium hexacarbonyl and 250 ml of dimethylformamide were heated at 12 ° C. for 8 hours under nitrogen. The emerging Solution was worked up as in Example 23. It was 1.45 g Ethyl decanoate and 3, o g gamma-decaniactone obtained, it being assumed that the chromium in this example is the transition

Cr ⁰ (in the form of carbonyl) -> Cr (I) ~ > Cr (II) ■ * Cr (III)

was subject.

009837/2282

Claims (14)

Claims 1) Process for the preparation of compounds of the form I 'Il I I I I Ii my> C = CR ¹ R ¹¹ Y, -CC-CR ¹ R ¹¹ Y, - (CC) CC Oil, (CC) CR ¹ R ¹¹ Y, Hl M «J ' ^ik I, lH || J, H (CC) CR ¹ R ¹¹ Y, H (CC) CC OH and / or> CC-CR ¹ R ' ¹ , thereby ι l ^ra II ^m l ι Il • O - CO characterized in that an organic halogen compound of the formula XCR ¹ R ¹¹ Y or an epoxide is brought into contact with an olefinic compound in the presence of a metal in the reduced state, v / which * is suitable for carrying out one-electron oxidation-reduction reactions, v / obei in the formulas R ¹ R ^{11 represent} substituent groups or hydrogen X is halogen Y represents a substituent group or hydrogen m represents an integer. 2) Process according to claim 1, characterized in that the compound of the formula XCR ¹ R ¹¹ Y is a chlorinated paraffin with up to 2o carbon atoms in the molecule or a chlorine aromatic compound such as chlorobenzene. 3) Process according to claim 1, characterized in that the compound of formula XCR ¹ R ¹¹ Y used is one in which Y is one of the groups -OH, -CIIO, -CONiI ₂ , -COOH, -CN, -COR or -COOR represents in which R is an alkyl or aryl group. 009837/2282 4) Method according to one of the preceding claims, characterized in that there is a halogen compound
aliphatic, especially paraffinic compound with up to
used to 2o carbon atoms. 5) Process according to one of the preceding claims, characterized in that the paraffinic halogen compound used is one of the formula X (CH ₉ ) Y, wherein η
represents an integer, preferably 1 to Io, such as ethylene chlorohydrin, propylene chlorohydrin, chloro- or bromoacetic acid
or an ester, a nitrile or an amide of these acids. * ι 6) Method according to one of the preceding claims, characterized in that the epoxide is an olefin oxide,
such as ethylene oxide, propylene oxide or butylene oxide, are used. 7) Method according to one of the preceding claims, characterized in that.man as an olefinic compound
an olefinic hydrocarbon with up to 20 carbon atoms, preferably an alpha-olefin, such as ethylene, propylene, IIexene-1, octene-1, dodecene-1 or tetradecene-1, is used. 8) Method according to one of the preceding claims, characterized in that a lower alpha-olefin such as ethylene at an olefin pressure or partial pressure of 5 to loo at starts. . 00 98 37/2282 9) Method according to one of the preceding claims, characterized in that the metal is iron, copper, titanium, Vanadium, uranium or preferably chromium are used. 10) method according to one of the preceding claims, characterized in that the metal is in the form of an Ilalogenide, in particular chloride, carboxylate, in particular alkanoate with up to 20 carbon atoms, or carbonyls are used. 11) Process according to one of the preceding claims, characterized in that the reaction is carried out in the presence an inert diluent such as an alcohol, a lower alkanoic acid, an acid derivative, a nitrile, a Ester, an ether or a ketone. 12) Process according to one of the preceding claims, characterized in that the reaction is carried out in the presence a metal sequestering agent or sequestering agent, such as ethylene J diamine, ethylenediaminetetraacetic acid or a ethanolamine or in the presence of a ligand such as an amine, a phosphine or an arsine. 13) Method according to one of the preceding claims, characterized in that the metal is converted back into the reduced state, for example electrolytically or with hydrazine or with sink and an acid. 009837/2282: 14) Method according to one of the preceding claims, characterized in that the reaction is carried out at a temperature in the range from τ5ο ° to 3oo ° C, preferably o ° to 2oo ° C, executes. 009837/2282