Attached proton test

APT Attached proton test, a modification of the J-modulated spin-echo experiment to determine C//multiplicities, a less sensitive alternative to DEPT... 

Attached Proton Test (APT), Gated Spin-Echo (GASPE), and... 

Figure 2.4 (A) Pulse sequence for the gated spin-echo (GASPE) or attached proton test (APT) experiment. (B) Effect of the pulse sequence on the C magnetization vectors of a CH group.

Figure 6. 50 MHz NMR spectrum of the masked poly(oxyethylene)-t -polyfpivalolactone) copoiymeric salt, 4, using attached proton test sequence (CH, CH3, Pos. CH2, C, neg.) in CDCI3 at 25°C.

APT, you will perhaps remember, stands for Attached Proton Test, meaning that this spectrum tells you the multiphcity of the signals (Me, CH2, CH or quaternary C). These two spectra tell you how many magnetically non-equivalent types of carbon are present in the molecule, but (for the reasons we discussed earlier) we do not use integration to try to find out relative numbers. We shall present APT spectra as follows CH, CH3 in negative phase (down), CH2 and quaternary C in positive phase (up). 

The J-MODulated (JMOD) C experiment, also known as Attached Proton Test (APT) was the first and simplest way to determine "C multiplicities. In contrast to DEPT no polarization transfer is included in the pulse sequence (Fig. 3.16) and as a consequence the signals of quaternary carbons are visible in the spectrum, but the sequence is far less sensitive than DEPT or INEPT. The value of D2 is used to differentiate between the different carbon multiplicities. The signal intensities of quaternary carbons are not influenced by the value of D2 for D2 equal to 1 CH and CH, groups have maximum negative intensity and CHj has maximum positive intensity. For D2 equal to 1 /C2 J, ) only the signals of quaternary carbons are visible. 

A solution of Cp2TiCl [52] (0.43 g, 2 mmol) in THF was added dropwise to a solution of the epoxide (1.0 mmol) in 20 mL of THF at room temperature. A solution of 1A HC1 in ether (4 mL) was added, and the mixture was stirred for 10 min. The precipitated solid was removed and the filtrate was added to excess (5 mL) of aqueous saturated sodium di-hydrogenphosphate. The organic layer was separated and the aqueous layer was extracted with ether. The product was isolated as a mixture of exo- and endo-Me isomers in 70% yield. The structures were confirmed by l3C-NMR, H-NMR, chemical shift correlation mapping, nOe measurements, and attached proton test (APT) experiments. No [a]D was recorded because the product was isolated as a mixture. 

Record the 1-D l3C compensated attached proton test (CAPT) spectrum (Braun et al., 1998, pp. 165-167). 

Figure F1.4.2 The aromatic region of the 1-D 1H NMR of cyanidin gives rise to a characteristic splitting pattern (upper spectrum). The lower spectrum shows the aromatic region of the 1-D 13C compensated attached proton test (CAPT) NMR spectrum of cyanidin. This spectrum contains all the fifteen 13C resonances of the aglycone in addition to solvent signals (labeled S) and the anomeric sugar proton labeled 1". In this spectrum, the 13C nuclei which have a proton attached are represented with resonances pointing downwards, while the quaternary 13C nuclei are pointing upwards. The 1H NMR experiment was obtained within 25 sec, while the CAPT experiment was obtained within 1 hr 46 min.

ID IQ 2D 2D-NMR 2h2o 2Q 3Q 9BEN A1 ABS AC ACM ACN AFM Al-CSM ALMA-i5 Al-m-EPDM AN AO APT ASTM ATR ATR-IR B/S BABA Two-dimensional Single-quantum One-dimensional Deuteron solid-state NMR Deuterated water Double-quantum Triple-quantum 9 borobicyclo [3, 3, 1] nonane Amide 1 Acrylonitrile-butadiene-styrene terpolymer Accelerator Acrylate rubber Acrylonitrile Atomic Force Microscopy Aluminium salt of chlorosulfonate polyethylene Allyl-rf5 methacrylate Aluminium salt of maleated EPDM Acrylonitrile 1-Allyl oxyoctane Attached Proton Test American Standards for Testing and Materials Attenuated total reflectance spectroscopy Attenuated total reflectance-IR spectroscopy Butadiene/styrene Back-to-back... 

The other experiment worth mentioning, which, by the way, is also obsolete, is the attached proton test or APT. This experiment is based on the different magnitudes of Tl—13C coupling for methine, methylene, and methyl groups. By adjusting certain delays in the pulse sequence (not given), quaternary and methylene carbons could be phased up, and methine and methyl carbons could be phased down. Since phase is arbitrary, this order could be reversed. This ability of distinguishing... 

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