318-5 - Organic Lecture Series CH 318 N LECTURE 5 Textbook...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
Organic Lecture Series 1 CH 318 N LECTURE 5 Textbook Assignment: Chapter 14- Mass Spec Homework (for credit): POW 2 posted Today’s Topics: NMR-splitting & examples Notice & Announcements: Organic Lecture Series 2 • Relative areas of signals are proportional to the number of H giving rise to each signal • Modern NMR spectrometers electronically integrate and record the relative area of each signal Signal Areas Signal Areas
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Organic Lecture Series 3 Chemical Chemical Shifts Shifts 1 H-NMR NMR RC H 2 OR (C H 3 ) 4 Si ArC H 3 H 3 RC C H RCC H 3 RO H RCH 2 O H H 2 R O O H 2 R R 3 C H R 2 N H H 2 R R 2 C=CRC H R 2 R 2 C=C H R H O RCO H O H 2 Cl H 2 Br H 2 I H 2 F Ar H O O R 2 C=C H 2 RCOC H 3 H 2 R ArO H 9.5-10.1 3.7-3.9 3.4-3.6 Type of Hydrogen 0 (by definition) Ch emical Shift ( δ ) 1.6-2.6 2.0-3.0 0.8-1.0 1.2-1.4 1.4-1.7 2.1-2.3 0.5-6.0 2.2-2.6 3.4-4.0 Ch emical δ ) 3.3-4.0 2.2-2.5 2.3-2.8 0.5-5.0 4.6-5.0 5.0-5.7 10-13 4.1-4.7 3.1-3.3 3.6-3.8 4.4-4.5 6.5-8.5 4.5-4.7 Organic Lecture Series 4 Chemical Shift Chemical Shift 1 H NMR H NMR
Background image of page 2
Organic Lecture Series 5 • Depends on (1) electronegativity of nearby atoms, (2) the hybridization of adjacent atoms, and (3) diamagnetic effects from adjacent pi bonds Electronegativity C H 3 OH C H 3 F C H 3 Cl C H 3 Br C H 3 I (C H 3 ) 4 C H 3 ) 4 Si CH 3 -X Electroneg- ativity of X Chemical Shift ( δ ) 4.0 3.5 3.1 2.8 2.5 2.1 1.8 4.26 3.47 3.05 2.68 2.16 0.86 0.00 Chemical Shift Chemical Shift 1 H NMR H NMR Organic Lecture Series 6 The higher s character, the greater the The higher s character, the greater the deshielding deshielding RC H 3 , R 2 C H 2 3 C H R 2 C=C H R, R 2 C=C H 2 H O R 2 C=C(R)C H R 2 RC C H Allylic Type of Hydrogen (R = alkyl) Name of Hydrogen δ ) Alkyl Acetylenic Vinylic Aldehydic 0.8 - 1.7 1.6 - 2.6 4.6 - 5.7 9.5-10.1 2.0 - 3.0 Chemical Shift Chemical Shift 1 H NMR H NMR
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Organic Lecture Series 7 Diamagnetic effects of pi bonds Diamagnetic effects of pi bonds – a carbon-carbon triple bond shields an acetylenic hydrogen and shifts its signal upfield (to the right) to a smaller δ value – a carbon-carbon double bond deshields vinylic hydrogens and shifts their signal downfield (to the left) to a larger δ value RC H 3 R 2 C=C H 2 RC C H Type of H Name Alkyl Vinylic Acetylenic 0.8- 1.0 4.6 - 5.7 2.0 - 3.0 Chemical Shift ( δ ) Chemical Shift Chemical Shift 1 H NMR H NMR Organic Lecture Series 8 Signal Splitting & the ( n + 1) Rule Peak: Peak: the units into which an NMR signal is split; doublet, triplet, quartet, etc.
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 18

318-5 - Organic Lecture Series CH 318 N LECTURE 5 Textbook...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online