Mole ratio control

Excess of S03 (poor mole ratio control), i.e., high conversion, low free oil... 

Mass flow measurement has been shown to be efficient as a mole ratio control, even where S03 mass flow was not measurable with sufficient accuracy in the diluted gas stream. 

Stripping off the film (misting) leads to loss of mole ratio control in the reactor when the mist droplets react with the SO3 gas. 

At present, Ballestra has installed automatic control of the SOj/organic mole ratio in at least six new sulphonation plants. The principles of the mole ratio control are indicated in P I diagram 8. This new development is feasible because accurate and technical reliable massflow meters are available now. 

Film sulphonation plant raw material flow control system Mole ratio control system... 

Staged reactions, where only part of the initial reactants are added, either to consecutive reactors or with a time lag to the same reactor, maybe used to reduce dipentaerythritol content. This technique increases the effective formaldehyde-to-acetaldehyde mole ratio, maintaining the original stoichiometric one. It also permits easier thermal control of the reaction (66,67). Both batch and continuous reaction systems are used. The former have greater flexibiHty whereas the product of the latter has improved consistency (55,68). 

The nitro alcohols available in commercial quantities are manufactured by the condensation of nitroparaffins with formaldehyde [50-00-0]. These condensations are equiUbrium reactions, and potential exists for the formation of polymeric materials. Therefore, reaction conditions, eg, reaction time, temperature, mole ratio of the reactants, catalyst level, and catalyst removal, must be carefully controlled in order to obtain the desired nitro alcohol in good yield (6). Paraformaldehyde can be used in place of aqueous formaldehyde. A wide variety of basic catalysts, including amines, quaternary ammonium hydroxides, and inorganic hydroxides and carbonates, can be used. After completion of the reaction, the reaction mixture must be made acidic, either by addition of mineral acid or by removal of base by an ion-exchange resin in order to prevent reversal of the reaction during the isolation of the nitro alcohol (see Ion exchange). 

Sodium tripolyphosphate is produced by calcination of an intimate mixture of orthophosphate salts containing the correct overall Na/P mole ratio of 1.67. The proportions of the two anhydrous STP phases are controlled by the calcination conditions. Commercial STP typically contain a few percent of tetrasodium pyrophosphate and some trimetaphosphate. A small amount of unconverted orthophosphates and long-chain polyphosphates also may be present. 

Urea—Formaldehyde Reaction Products. Urea—formaldehyde (UF) reaction products represent one of the older controlled release nitrogen technologies. An early disclosure of the reaction products of urea [57-13-6] and formaldehyde [50-00-0] was made in 1936 (1) (Amino resins and plastics). In 1948, the USDA reported that urea (qv) and formaldehyde (qv) could react to produce a controlled release fertilizer at urea to formaldehyde mole ratios (UF ratio) greater than one (2). 

All lene Oxides and Aziridines. Alkyleneamines react readily with epoxides, such as ethylene oxide [75-21-8] (EO) or propylene oxide [75-56-9] (PO), to form mixtures of hydroxyalkyl derivatives. Product distribution is controlled by the amine to epoxide mole ratio. If EDA, which has four reactive amine hydrogens, reacts at an EDA to EO mole ratio which is greater than 1 4, a mixture of mono-, di-, tri,-, and tetrahydroxyethyl derivatives of EDA are formed. A 10 1 EDA EO feed mole ratio gives predominandy 2-hydroxyethylethylenediamine [111-41-1], the remainder is a mixture of bis-(2-hydroxyethyl)ethylenediamines (7). If the reactive NH to epoxide feed mole ratio is less than one and, additionally, a strong basic catalyst is used, then oxyalkyl derivatives, like those shown for EDA and excess PO result (8,9). 

Aziridines react with alkyleneamines iu an analogous fashion to epoxides (10,11). Product distribution is controlled by the alkyleneainine-to-aziridine mole ratio. 

From these and other related equations, it can be seen that, by using internal programs based on phosphate blends with specific sodium-to-phosphate (Na PQ4) mole ratios, BW alkalinity may be controlled... 

An exception to the above are fatty acid methyl esters, which, due to the reaction mechanism involving molecular rearrangements with excess S03, have to be sulfonated at a slightly higher mole ratio of S03 to methyl esters (namely, 1.15-1.20/L). Outside the reaction tubes, in the reactor jacket, cooling water is circulated to control the liquid-film temperature and removing the reaction heat. 

The mass flow is continuously detected and controlled in-line by means of modem mass flow meters. The practical accuracy achievable is such as to keep, with a time delay of few seconds, a fluctuation range for the mole ratio of less than 0.5%. 

As a consequence, molecular weight control is easy to achieve, provided initiation is fast with respect to propagation. The number average degree of polymerization is given by the mole-ratio of monomer consumed to initiator. 

Anionic polymerizations carried out in aprotic solvents with an efficient initiator may lead to molecular weight control (Mn is determined by the monomer to initiator mole ratio) and low polydispersity indices. The chains are linear and the monomer units are placed head-to-tail. Such polymers are commonly used as calibration samples and for investigation of structure-properties relationships. 

Experimental Results. The inhibition of NDEIA formation after days at 37 forthree water-soluble and three oil-soluble inhibitors is displayed in Tables II and III, respectively. So that relative effectiveness could be compared, the concentration of each inhibitor was chosen to provide an inhibitor/nitrite mole ratio = 10, Each inhibitor was tested in two separate emulsion batches with two or more aliquots analyzed. The data shown for positive controls are from similar replicate experiments. 

During this study it was however found that the multiple esterification processes were highly dependent on the acyl reagent used. Different protection patterns could be acquired from the same starting material by control of temperature, acyl reagents, reagent mole ratio, and solvent polarity (Scheme 8, 9,10). 

Scheme 8. Multiple benzoylation controlled by temperature and reagent mole ratio.

The rate of polymerization by the 16 (n=10)-3f system is dependent on the concentration of 3f When the initial mole ratio of 3f to PO was increased from 0.025 to 2.5 mol%, the polymerization was much more accelerated to attain 94.1% conversion in only 3 min (Fig. 28). If the added 3f initiates the polymerization, the number of the polymer molecules produced should increase incrementally in relation to the amount of 3f, and the Mn value should decrease. However, irrespective of the mole ratio of 3f to PO (0.025-2.5 mol%), the observed Mn values at 100% conversion were all close to the theoretical Mn (11,600) as indicated by the ratio of the numbers of the molecules of polymer and 16 (Np/AT pp) (Fig. 29) [61] being almost constant at unity, and the produced polymers were all of narrow MWD. The Mn of the polymer could be controlled by... 

Zinc N-phenylporphyrin (17) also brings about the living polymerization of PS, affording a polymer of controlled molecular weight with a narrow MWD. The polymerization with the initial mole ratio [PS]o/[17]q of 400 proceeded up to 88% conversion in 50 min at 25 °C, giving a polymer with Mn and Mw/Mn of 24,400 and 1.05, respectively. 

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