CN1515540A

CN1515540A - New synthesis process of tert-butylamine

Info

Publication number: CN1515540A
Application number: CNA031339042A
Authority: CN
Inventors: 周新锐; 陈有刚; 刘博�
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2003-08-31
Filing date: 2003-08-31
Publication date: 2004-07-28

Abstract

The present invention belongs to the field of chemical technology, relates to a new process for synthesizing tert-butylamine. It adopts MTBE (methyl tert-butyl ether) and urea process, and includes the following steps: dissolving the fully-pulverized urea in 96% concentrated sulfuric acid, then drop-adding MTBE within 1-2 hr., retaining temp. at 20-25 deg.C, filtering to obtain tert-butylurea crystal, finally dissolving the tert-butylurea in 40% NaOH aqueous solution, refluxing for 4 hr. and then distilling and collecting fraction with 42-46 deg.C so as to obtain tert-butylamine.

Description

Novel synthesis process of tert-butylamine

Technical Field

The invention belongs to the technical field of chemical industry, and relates to a new synthesis process of a rubber accelerator NS and a raw material tert-butylamine serving as an intermediate of a rifampicin drug.

Technical Field

Tert-butylamine (TBA) is an important organic synthetic intermediate, widely used in the synthesis of rubber vulcanization accelerators, drugs (rifampicin), insecticides, fungicides, herbicides, dyes, and the like. At present, the main methods for producing tert-butylamine at home and abroad comprise:

(1) the HCN-MTBE process is a hydrocyanic acid-methyl tert-butyl ether process. As the synthesis process of the tert-butylamine in the Chinese patent 02109522.1: MTBE and hydrocyanic acid generate tert-butyl formamide under the action of concentrated sulfuric acid, and then the tert-butyl formamide is generated by alcoholysis of methanol. However, there is a great risk in production because of cyanide in the process route.

(2) The tertiary butanol urea method: reacting urea with tert-butyl alcohol at 10-20 ℃ to generate tert-butyl urea, and hydrolyzing under alkaline conditions to obtain tert-butylamine. For example, an improved process for synthesizing tert-butylamine by using tert-butyl urea as raw material in Chinese patent 99112017.5 discloses an improved process for synthesizing tert-butylamine by using tert-butyl urea through alkaline hydrolysis and distillation and recovering a deflocculating agent (ethylene glycol). The synthesis of the tert-butylamine in the route uses a high boiling point solvent, namely ethylene glycol, which can be recycled but has high energy consumption and poor effect.

(3) The catalytic amination method of isobutene comprises the following steps: isobutylene and ammonia gas are directly subjected to gas phase catalytic ammoniation to prepare the tert-butylamine. As described in us patent 4929758: under 300 ℃ and 500Mpa, the selectivity of tert-butylamine is 97.6 percent by taking iron-silicon as a catalyst and the ratio of ammonia to isobutene is 5: 1; diatomite is used as a catalyst, the ratio of ammonia to isobutene is 2: 1, the selectivity of tert-butylamine obtained under the conditions of 300 ℃ and 250Mpa is 99.8 percent, and unreacted raw materials can be recycled. Therefore, the process needs high-temperature and high-pressure conditions, is harsh and is not suitable for domestic production.

Disclosure of Invention

The invention aims to provide a process for synthesizing tert-butyl urea by using urea and MTBE (methyl tert-butyl ether) under the catalysis of concentrated sulfuric acid, and then adding the tert-butyl urea into 40% NaOH aqueous solution to distill out tert-butyl amine.

The technical scheme of the invention is as follows:

l, synthesis of intermediate tert-butyl urea

Metered concentrated sulfuric acid (98%) is added into a reactor provided with a stirrer, ground urea is slowly added under stirring, the temperature is controlled to be 20-25 ℃, and then MTBE is dropwise added within l-2 hours. Adding MTBE, stirring at the constant temperature for about half an hour, stopping stirring, and standing for more than 16 hours. The material proportion for synthesizing the tert-butyl urea is as follows: MTBE, urea and concentrated sulfuric acid = l: 1: 2.

After the standing reaction is finished, the pH value of a reactant is adjusted to 3-6 by using a 40% NaOH aqueous solution, tert-butyl urea is separated out, and tert-butyl urea crystals (the water content is about 20%) can be obtained through separation, washing and recrystallization, and the tert-butyl urea crystals can be directly used for alkaline hydrolysis without being dried. The yield of tert-butylurea (dry basis) was above 90% based on MTBE.

2. Synthesis of tert-butylamine

Adding metered tert-butyl urea into a reflux distillation reactor provided with a stirrer, then adding 40% NaOH aqueous solution, refluxing for 3 hours, then distilling, and collecting fractions at 42-46 ℃to obtain tert-butylamine, wherein the yield of the tert-butylamine is over 98% in terms of tert-butyl urea, and the purity of the tert-butylamine is over 95%.

Compared with the existing tert-butylamine synthesis process, the method has the characteristics of high yield, low cost, remarkable economic benefit and the like. Compared with the foreign isobutene ammoniation method, the process of the invention does not need high temperature and high pressure; compared with the MTBE cyaniding method, the method has the advantages of no cyanide pollution, less equipment investment, safer production, no three-waste pollution, lower production cost than that at home and abroad, and obvious economic benefit competitive advantage, thereby having popularization and application values.

The specific implementation mode is as follows:

the following detailed description describes embodiments of the invention:

l, preparation of butyl urea: in a 250 ml three-neck flask (comprising stirrer, a 100 ml funnel, a thermometer), 97 g (53 ml, 0.99 mol) of concentrated sulfuric acid, ice bath and 30 g (0.5 mol) of well-ground urea were placed, the rate of addition was slowed down, the temperature was maintained between 20 and 25 ℃ and the urea was almost completely dissolved in the concentrated sulfuric acid. Then 44 g (0.5 mol) of MTBE was added over three hours in a funnel, the temperature was maintained at 20 to 25 ℃, after addition, stirring was carried out for 30 minutes, and left to stand at room temperature for 16 hours without removing the precipitate, and the mixture was made alkaline by adding caustic soda (2 mol, 375 ml of water) to discolor the licorice red indicator. The temperature was kept below 25 ℃ and the mixture was cooled in ice water with stirring until it reached approximately 15 ℃ at which timethe precipitate was collected in a 15 cm long buchner funnel, washed with 2 100 ml cold water, pressed, sucked as dry as possible, then transferred to a 1 l beaker, 200 ml water added, heated to boiling (at which point a large amount of precipitate dissolved in water), and filtered rapidly (buchner funnel heated with 8 cm long steam). White t-butylurea was collected together, pressed, sucked, dried as good as dry, spread on a paper sucker, and then dried in air. Approximately 60g of crude tert-butylurea are obtained.

2. Preparation of tert-butylamine:

a200 mL round bottom flask was charged with 15 g of sodium hydroxide dissolved in 20 mL of water, followed by 18 g of tert-butylurea (previously prepared), equipped with a good reflux condenser and a gas absorber, slowly refluxing the combined liquid for about 4 hours, the flask was cooled and equipped with a distillation apparatus, the 40 to 46 ℃ fraction was collected in a cooled receiver (flask), crude amine was formed, air dried overnight, dried with a small amount of a strong desiccant, redistilled, and the 42 to 46 ℃ fraction was collected to obtain about 12 g of tert-butylamine. The purity is over 95 percent by gas chromatography inspection.

Claims

1. A new process for synthesizing tert-butylamine features that urea and MTBE (methyl tert-butyl ether) are used to synthesize tert-butyl urea under the catalysis of concentrated sulfuric acid, and then the tert-butyl urea is added to 40% aqueous solution of NaOH to distill out tert-butylamine, which features that:

(1) synthesis of tert-butylurea:

slowly adding fully crushed urea into concentrated sulfuric acid (98%), keeping the temperature at20-25 ℃ until the urea is completely dissolved in the concentrated sulfuric acid, then dropwise adding MTBE within 1-2 hours, wherein the molar ratio of MTBE to urea to concentrated sulfuric acid (96%) is 1: 2, stirring for half an hour, standing for 16 hours at room temperature, adding 40% NaOH to separate out tert-butyl urea, and the molar ratio of NaOH to concentrated sulfuric acid (96%) is 1: 1.

(2) Synthesis of tert-butylamine:

tert-butylurea was added to a 40% aqueous solution of NaOH at a molar ratio of 1: 2, followed by refluxing with stirring for 4 hours, and then tert-butylamine was distilled off.

2. The process of claim 1, wherein the tert-butyl urea is synthesized from MTBE.

3. The process of claim 1, wherein the tert-butyl urea is causticized and hydrolyzed in the hydrolysate, refluxed for 4 hours, and distilled to collect 42-46 ℃ fraction to obtain tert-butyl amine.