Propylene glycol, synthesis from

Simonov MN, Zaddn PA, Simakova IL (2012) Highly selective catalytic propylene glycol synthesis from alkyl lactate over copper on silica performance and mechanism. Appl Catal B 119-120 340-347... 

Huang S, Ma J, Li J, Zhao N, Wei W, Sun Y (2008) Efficient propylene carbonate synthesis from propylene glycol and carbon dioxide via organic bases. Catal Commun 9 276-280... 

Silva, E.D. Dayoub, W Mignani, G. Raoul, Y Lemaire, M. Propylene Carbonate Synthesis from Propylene Glycol, Carbon dioxide and Benzonitrile by AlkaU Carbonate Catalysts. Catal. Comm. 2012,29, 58-62. 

As early as 1904, 1,2-Propanediol Dinitrate was proposed (Ref 3) as an additive to lower the freezing temp of NG, but its practical application on a large scale was hindered by lack of the raw material, propane-1,2-diol. It is only recently that the synthesis of glycol from ethylene led to the development of a method for producing methyl glycol from propylene via cnioro-hydrin. Even so, propylene-1,2-glycol is somewhat more expensive than glycols derived from ethylene (Ref 9)... 

Rao, K.V.S., Srinivas, B., Subrahmanyam, M., and Prasad, A.R. (2000) A novel one step photocatalytic synthesis of dihydropyrazine from ethylenediamine and propylene glycol. Chemical Communications (16), 1533-1534. 

Tab. 3.9 Synthesis of ketal from cineole ketone and propylene glycol (Ri = CH3 R2 H).

From a study of the fluoroacetates so far mentioned, it appears that any compound which can give rise to fluoroacetic acid (or the fluoroacetate ion), either by hydrolysis or by oxidation (or both), is toxic. The toxic grouping is thus F-CH2-CO, and any substitution in this radical destroys the toxicity as far as relatively simple compounds are concerned. We had reached this conclusion by May 1943.1 We subsequently showed that esters of / -fluoropropionic acid were non-toxic, whereas esters of y-fluorobutyric acid were shown by American workers to be toxic. In 19442 we reported the synthesis of ethyl 5-fluoro-pentanecarboxylate, F,[CH2]g C02Et (I). This is a stable, colourless liquid and we showed that it possessed very potent toxic properties of the fluoroacetate type. By subcutaneous injection of the propylene glycol solution into mice the l.d. 50 was 4 mg./kg. Methyl fluoroacetate (II) may be taken as a convenient standard (p. 115) and has a l.d. 50 of about 6 mg./kg. for saline solutions, and 15 mg./kg. for propylene glycol solution.3 Therefore ethyl 5-fluoropentanecarboxylate was about 7 times as toxic as methyl fluoroacetate (molecule for molecule).4... 

The kind of approach that must be employed is illustrated in Scheme 3 for the synthesis of (55)-80 starting from the 2-tetrahydropyranyl (THP) ether of (S)-propylene glycol (Figure 14c), which can be obtained (124) in two steps from ethyl (5)-lactate. 

Prior to this time, other ventures had already been operating to produce commercial quantities of aliphatic chemicals from petroleum sources. Truly commercial production of ethylene glycol had been achieved by 1925 (10) using natural gas fractions as a starting material, and even earlier (about 1920) there had been the manufacture of isopropyl alcohol from cracking plant propylene (20), which may be termed the pioneer operation on a successful, continuing basis in the sphere of aliphatic synthesis from petroleum. 

The stream from the reaction section is first distilled to remove unconverted propylene, whose recycle, added to the make-up, represents the feed of the first epoxidation stage. Excess propane is also removed by distillation (—50 to 60 trays) to prevent its buildup in tfie synthesis loop. The heavy end of the first column is sent to the purification train for products for which the temperatures cannot exceed 100°C to avoid undesirable degradation. On account of the boiling points at standard pressure of the components present, this makes operation under vacuum necessary. Crude propylene oxide is collected at the top of the first distillation column (50 trays), and r-butyl alcohol at the1bottom, with some hydroperoxide, the catalyst, propylene glycol, aldehydes, esters etc. This stream is sent to a r-butyl alcohol separation column (35 to 40 trays), where the alcohol is recovered at the top. 

The aeylative cyclization of phenol with acetic anhydride was carried out over CeY type zeolites. The reaction mechanism is given in Fig. 4. At 380°C, the yield of 4-methyl coumarin was 75 % at 81% conversion of phenol. N-Methylpyrrolidine was synthesized from 1,4-butanediol and methylamine over Cr ZSM-5 and modified ZSM-5 catalysts at 300 C. The reaction mechanism is given in Fig. 5. The synthesis of a number of five- and six- membered heterocyclics have been depieted in Table 1. The reaction was carried out at 250-400°C at 30-80 hydrogen atm., under down-flow fixed bed conditions. The yield of N-methyl piperazine was 90% at 95% conversion over ZSM-5 catalysts. Similarly 2-methyl pyrazine and piperazine were synthesized from propylene glycol and ethylenediamine over HZSM-5 (Fig. 6). 

Synthesis of poly(aspartic add) from maleic acid derivatives and from aspartic acid under microwave irradiation conditions has been described by Pielichowski et al. (Scheme 14.33) [69, 70]. The reactions were performed in propylene glycol solutions in the temperature range 160 to 230 °C in a multimode microwave reactor. Poly(aspartic acid) with number-average molecular weights of 6150 to 18 500 g mol was obtained in good yield (50 to 85%). 

The cyclization of ethylenediamine (EDA) and propylene glycol (PG) over a mixture of zinc and chromium oxides to 2-methylpyrazine (MP) is a basic step in the synthesis of 2-amidopyrazine, a well-known antitubercular drug. This is a highly complex reaction in which EDA and PG each react independently to give a variety of products, as shown in Table 5.1. (Forni and Miglio, 1993). We desire to find the number of independent reactions from this set. 

Most importantly, layered materials are currently of particular interest as supports for the immobihzation and/or intercalation of various ILs in order to prepare polymer nanocomposites [83, 84] with improved thermal and mechanical properties, nanohybrid materials for electrochemical sensors [85, 86], and efficient catalysts for the synthesis of cyclic carbonate by the cycloaddition of CO2 to allyl glycidyl ether [87] and propylene glycol methyl ether (PGME) from propylene oxide and methanol [88]. A detailed list of applications involving layered materials and ILs can be found in a recent review [16]. 

C12H2ooio,MO,H O. The synthesis of alanine, C H NOS by Strecker from aldehyde ammonia, formic acid, and hydrocyanic acid, and the conversion of alanine into lactic acid by means of nitrous acid, seemed to indicate the formula C H O for lactic acid, and this was confirmed by Wurtz, who obtained it by oxidisihg propylene glycol, at the same time regarding it as dibasic (C = 12, O = 16) ... 

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