Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
  • C07C269/06—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups by reactions not involving the formation of carbamate groups
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
  • C07C269/02—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups from isocyanates with formation of carbamate groups

Definitions

• the invention relates to an improved process for the preparation of iodine alkynyl carbamates.
• Iodine alkynyl carbamates have long been known as antimicrobial agents.
• EP-PS-93 962 describes substituted 2- (3-iodo-2-propynyloxy) ethanol carbamates and a process for their preparation in which equimolar amounts of iodoalkynyl alcohols are reacted with isocyanates. Since the use of iodoalkynyl alcohols is problematic because of their explosive properties, alternative methods have been proposed in which this intermediate is avoided.
• EP-PS-14 032 describes a process for the preparation of iodoalkynylcarbamates, in which an alkynyl alcohol is first reacted with an isocyanate to give the corresponding carbamate and this carbamate is then iodinated in aqueous alkaline solution to give the corresponding iodoalkynyl carbamate.
• this process has the disadvantage that additional cleaning measures such as extraction with water-insoluble organic solvents such as toluene are required.
• additional cleaning measures are on the one hand complex, on the other hand further measures are required to free the iodoalkynyl carbamate from the organic solvent.
• the object was therefore to develop an improved process for the preparation of iodoalkynylcarbamates which avoids the disadvantages of the known prior art and in which, in particular, light-colored products are obtained without complex cleaning operations such as extraction with organic solvents being carried out have to.
• radicals Rl and R2 independently of one another are hydrogen or linear or branched alkyl radicals having 1 to 6 C atoms
• radicals R * * - * to R6 independently of one another are hydrogen or linear or branched alkyl radicals with 1 to 4 C atoms
• n denote the number 0 or 1
• the corresponding alkynyl alcohol being first reacted with the corresponding isocyanate to give the carbamate, this carbamate in alkaline solution iodized, the alkaline reaction mixture neutralized with carbon dioxide and the iodoalkynyl carbonate then filtered off.
• the present invention thus relates to a process for the preparation of iodoalkynyl carbamates of the general formula (I)
• radicals R ** - and R- independently of one another are hydrogen or linear or branched alkyl radicals having 1 to 6 C atoms
• radicals R3 to R ⁇ independently of one another are hydrogen or linear or branched alkyl radicals with 1 to 4 C atoms
• the rest R7 is hydrogen, a linear or branched alkyl radical
• n 1 to 12 carbon atoms, a cyclohexyl radical, a substituted or unsubstituted phenyl radical, a benzyl radical or a p-toluenesulfonyl radical and n represent the number 0 or 1, with firstly an alkynyl alcohol of the general formula
• R- 7 has the meaning given above, to a carbamate of the general formula (IV) HC ⁇ CC (RlR) -0- [C (R 3 R) -C (R5R 6 ) -0] n -C0NHR7 (IV)
• the carbamate (IV) is iodized in alkaline solution, the alkaline reaction mixture is neutralized and the iodoalkynyl carbamate (I) is then filtered off, and the neutralization is carried out using carbon dioxide.
• the process according to the invention has the advantage that light-colored iodalkynylcarbamates are obtained directly without additional cleaning operations having to be carried out.
• the process according to the invention relates to the production of iodoalkynyloxyalkylcarbamates, ie. H. to compounds of the general formula (I) in which n denotes the number 1.
• alkynyl alcohols of the general formula (II) are known compounds.
• prop-2-yn-1-ol propargyl alcohol
• Beil ⁇ stein's Handbuch der Organischen Chemie By adding ethylene oxide (EO) to propinols, corresponding propinol-EO adducts are accessible. T. are commercially available. From the homolog mixtures of these EO adducts, the individual indivi dues can be obtained by enrichment processes, e.g. B. fractional distillation, in pure form.
• Suitable isocyanates of the general formula (III) are: a) alkyl isocyanates, e.g. B. dodecyl, octyl, hexyl isocyanates and especially lower alkyl isocyanates such as butyl, propyl, ethyl and methyl isocyanate and a wide variety of structural isomers thereof; b) cycloalkyl isocyanates, e.g. B.
• cyclohexyl isocyanate c) onocyclic aryl isocyanates such as phenyl, 4-chlorophenyl and 3,4-dichlorophenyl, benzyl and p-toluenesulfonyl isocyanate
• the first stage of the process according to the invention the reaction of the alkynyl alcohol (II) with an isocyanate (III), is carried out by means of methods which are well known to those skilled in urethane chemistry.
• the isocyanate can be added to the alkynyl alcohol in a controlled manner in such a way that the reaction temperature can easily be kept constant; if required, external cooling can be used.
• the reaction can be carried out in the absence of a solvent; however, it is also possible to use a solvent which is inert to isocyanates.
• suitable solvents are esters such as ethyl acetate, butyl acetate and 2-ethoxyethyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, hydrocarbons such as toluene or xylene, halogenated hydrocarbons such as trichlorethylene, methylene chloride, 1,1,1-trichloroethane and tetrachloroethane and polar aprotic solvents such as dimethylformamide and dimethylacetamide.
• esters such as ethyl acetate, butyl acetate and 2-ethoxyethyl acetate
• ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone
• hydrocarbons such as toluene or xylene
• halogenated hydrocarbons such as trichlorethylene,
• catalysts that accelerates the reaction of isocyanates and alcohols.
• examples of such catalysts are organic or inorganic bases and soluble metal compounds, eg. B. iron and manganese acetylacetonate, dibutyltin dilaurate and zinc octanoate, lead tetraacetate, basic lead acetate and lead 2-ethylhexanoate.
• the second stage of the process according to the invention the iodination of the carbamate (IV), is carried out in an alkaline medium.
• the choice of the iodination agent used is not subject to any particular restrictions.
• elemental iodine in the form of powder or pellets can be used, but it is also possible, among other things, to use a mixture of sodium hypochlorite and an alkali metal iodide or a mixture of use of sodium hypochlorite, an alkali metal hydroxide and iodine.
• the iodinating agent is usually used in approximately equimolar amounts, based on the carbamate (IV); it may be desirable to use the iodination agent in a slight deficit or a slight excess.
• the second stage of the process according to the invention is generally carried out in the presence of an organic solvent; polar, water-miscible solvents are preferred.
• Alcohols such as methanol, ethanol, propanol or i-propanol are particularly advantageous. It is particularly preferred to use methanol and to work under largely or completely anhydrous conditions. If the latter mode of operation is selected, the reaction mixture is added after the iodination reaction has ended, ie. H. before the neutralization, water to (see Example 1).
• the carbamate (IV) may also be desirable to carry out the iodination of the carbamate (IV) in an aqueous medium.
• One possibility is e.g. B. adding a surfactant to the aqueous alkaline system; the effect of this is that the carbamate (IV) is emulsified or dispersed and is therefore in a finely divided state throughout the reaction time and is more susceptible to attack by the iodinating agent.
• the temperature is preferably kept below 30 ° C. during the second stage of the process according to the invention.
• the reaction mixture can be kept at the desired temperature by any known device that allows appropriate heat transfer and temperature control.
• the carbon dioxide used in the course of the inventive method for neutralization can be used in the solid or gaseous state. For example, it is possible to carry out the neutralization by adding dry ice in portions; for practical reasons, however, it is preferred to effect the neutralization by introducing CO 2 gas into the alkaline reaction mixture.
• the process is usually carried out at atmospheric pressure, for example in a simple stirring vessel with a corresponding heating / cooling and stirring device.
• a conventional type of motor-driven agitator can be used, but it is sometimes desirable, especially when working in large vessels, to use high-speed shear agitators at a few thousand revolutions per minute in order to ensure appropriate mixing and a uniform temperature in the to maintain the entire reaction mixture.
• the process according to the invention has the advantage that the intermediate carbamate (IV) does not have to be isolated. Rather, a preferred embodiment of the present invention is to carry out the entire process in the same container without isolating intermediate products.
• a further preferred embodiment of the present invention therefore consists in metering the total amount of the iodinating agent used into the reaction mixture.
• Propinyloxyethanol was obtained by fractional distillation from "Golpanol PME” (from BASF), an adduct of ethylene oxide with propinol (propargyl alcohol).
• the yield of 2- (3-iodo-2-propynyloxy) -ethyl-N-phenylcarbamate was 160.5 g or 93% of the theoretical amount; the product had a melting point of 98-101 ° C. The color of the product was dazzling white.
• the yield was 92.6% of the theoretical amount.
• the color of the product was dazzling white.
• the yield of 2- (3-iodo-2-propynyloxy) ethyl N-phenyl carbamate was 155 g or 90% of the theoretical amount; the product had a melting point of 97-100 ° C.
• the color of the product was dazzling white.
• Example 1 was repeated, except that 50% sulfuric acid was added dropwise to neutralize the highly alkaline reaction mixture until a pH of 8 was reached.
• the yield was as in Example 1, but the color of the product was dark brown.
• Example 1 was repeated, but 18% hydrochloric acid was added dropwise to neutralize the highly alkaline reaction mixture until a pH of 8 was reached.
• the yield was as in Example 1, but the color of the product was dark brown.

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• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (3)

• 1992
  • 1992-12-16 DE DE19924242483 patent/DE4242483A1/de not_active Withdrawn
• 1993
  • 1993-08-20 TW TW82106748A patent/TW237443B/zh active
  • 1993-12-07 WO PCT/EP1993/003442 patent/WO1994013627A1/de not_active Ceased
  • 1993-12-15 CN CN 93120836 patent/CN1094032A/zh active Pending

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